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1.  Effects of exercise on mobility in obese and non-obese older adults 
Obesity (Silver Spring, Md.)  2009;18(6):1168-1175.
Coupled with an aging society, the rising obesity prevalence is likely to increase the future burden of physical disability. We set out to determine whether obesity modified the effects of a physical activity intervention designed to prevent mobility disability in older adults. Older adults at risk for disability (N = 424, age range: 70-88 years) were randomized to a 12 month physical activity (PA) intervention involving moderate intensity aerobic, strength, balance and flexibility exercise (150 min per week) or a successful aging (SA) intervention involving weekly educational workshops. Individuals were stratified by obesity using a body mass index ≥ 30 (n = 179). Mobility function was assessed as usual walking speed over 400 meters and scores on a short physical performance battery (SPPB), which includes short distance walking, balance tests and chair rises. Over 12 months of supervised training, the attendance and total amount of walking time was similar between obese and non-obese subjects and no weight change was observed. Non-obese participants in the PA group had significant increases in 400 meter walking speed (+1.5%), while their counterparts in the SA group declined (−4.3%). In contrast, obese individuals declined regardless of their assigned intervention group (PA: −3.1%; SA: −4.9%). SPPB scores, however, increased following PA in both obese (PA: +13.5%; SA: +2.5%) and non-obese older adults (PA: +18.6%; SA: +6.1%). A moderate intensity PA intervention improves physical function in older adults, but the positive benefits are attenuated with obesity.
doi:10.1038/oby.2009.317
PMCID: PMC3114403  PMID: 19834467
2.  Leisure Time Physical Activity of Moderate to Vigorous Intensity and Mortality: A Large Pooled Cohort Analysis 
PLoS Medicine  2012;9(11):e1001335.
Analyzing data from over 650,000 individuals, Dr. Steven Moore and colleagues report that greater amounts of leisure-time physical activity were associated with higher life expectancy across a wide range of activity levels and body mass index groups.
Background
Leisure time physical activity reduces the risk of premature mortality, but the years of life expectancy gained at different levels remains unclear. Our objective was to determine the years of life gained after age 40 associated with various levels of physical activity, both overall and according to body mass index (BMI) groups, in a large pooled analysis.
Methods and Findings
We examined the association of leisure time physical activity with mortality during follow-up in pooled data from six prospective cohort studies in the National Cancer Institute Cohort Consortium, comprising 654,827 individuals, 21–90 y of age. Physical activity was categorized by metabolic equivalent hours per week (MET-h/wk). Life expectancies and years of life gained/lost were calculated using direct adjusted survival curves (for participants 40+ years of age), with 95% confidence intervals (CIs) derived by bootstrap. The study includes a median 10 y of follow-up and 82,465 deaths. A physical activity level of 0.1–3.74 MET-h/wk, equivalent to brisk walking for up to 75 min/wk, was associated with a gain of 1.8 (95% CI: 1.6–2.0) y in life expectancy relative to no leisure time activity (0 MET-h/wk). Higher levels of physical activity were associated with greater gains in life expectancy, with a gain of 4.5 (95% CI: 4.3–4.7) y at the highest level (22.5+ MET-h/wk, equivalent to brisk walking for 450+ min/wk). Substantial gains were also observed in each BMI group. In joint analyses, being active (7.5+ MET-h/wk) and normal weight (BMI 18.5–24.9) was associated with a gain of 7.2 (95% CI: 6.5–7.9) y of life compared to being inactive (0 MET-h/wk) and obese (BMI 35.0+). A limitation was that physical activity and BMI were ascertained by self report.
Conclusions
More leisure time physical activity was associated with longer life expectancy across a range of activity levels and BMI groups.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Regular physical activity is essential for human health. It helps to maintain a healthy body weight and prevents or delays heart disease, type 2 diabetes, and some cancers. It also makes people feel better and increases life expectancy. The World Health Organization (WHO) currently recommends that adults do at least 150 minutes of moderate- to vigorous-intensity physical activity every week. Moderate-intensity physical activities (for example, brisk walking and gardening) require a moderate amount of effort and noticeably increase the heart rate; vigorous-intensity physical activities (for example, running or fast swimming) require a large amount of effort and cause rapid breathing and a substantial heart rate increase. Worryingly, people in both developed and developing countries are becoming increasingly physically inactive. People are sitting at desks all day instead of doing manual labor; they are driving to work in cars instead of walking or cycling; and they are participating in fewer leisure time physical activities.
Why Was This Study Done?
Although various studies suggest that physical activity increases life expectancy, few have quantified the years of life gained at distinct levels of physical activity. Moreover, the difference in life expectancy between active, overweight individuals and inactive, normal weight individuals has not been quantified. Thus, it is hard to develop a simple public health message to maximize the population benefits of physical activity. In this pooled prospective cohort analysis, the researchers determine the association between levels of leisure time physical activities, such as recreational walking, and years of life gained after age 40, both overall and within body mass index (BMI) groups. A pooled prospective cohort analysis analyzes the combined data from multiple studies that have followed groups of people to investigate associations between baseline characteristics and outcomes such as death. BMI is a ratio of weight to height, calculated by dividing a person's weight by their height squared; normal weight is defined as a BMI of 18.5–24.9 kg/m2, obesity (excessive body fat) is defined as a BMI of more than 30 kg/m2.
What Did the Researchers Do and Find?
The researchers pooled self-reported data on leisure time physical activities and BMIs from nearly 650,000 individuals over the age of 40 years enrolled in one Swedish and five US prospective cohort studies, most of which were investigating associations between lifestyle factors and disease risk. They used these and other data to calculate the gain in life expectancy associated with specific levels of physical activity. A physical activity level equivalent to brisk walking for up to 75 minutes per week was associated with a gain of 1.8 years in life expectancy relative to no leisure time activity. Being active—having a physical activity level at or above the WHO-recommended minimum of 150 minutes of brisk walking per week—was associated with an overall gain of life expectancy of 3.4–4.5 years. Gains in life expectancy were seen also for black individuals and former smokers, groups for whom relatively few data had been previously available. The physical activity and life expectancy association was also evident at all BMI levels. Being active and normal weight was associated with a gain of 7.2 years of life compared to being inactive and class II+ obese (having a BMI of more than 35.0 kg/m2). However, being inactive but normal weight was associated with 3.1 fewer years of life compared to being active but class I obese (having a BMI of 30–34.9 kg/m2).
What Do These Findings Mean?
These findings suggest that participation in leisure time physical activity, even below the recommended level, is associated with a reduced risk of mortality compared to participation in no leisure time physical activity. This result may help convince currently inactive people that a modest physical activity program may have health benefits, even if it does not result in weight loss. The findings also suggest that physical activity at recommended levels or higher may increase longevity further, and that a lack of leisure time physical activity may markedly reduce life expectancy when combined with obesity. Although the accuracy and generalizability of these findings may be limited by certain aspects of the study's design (for example, some study participants may have overestimated their leisure time physical activity), these findings reinforce the public health message that both a physically active lifestyle and a normal body weight are important for increasing longevity.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001335.
The World Health Organization provides information about physical activity and health (in several languages); its 2010 Global Recommendations on Physical Activity for Health is available in several languages
The US Centers for Disease Control and Prevention provides information on physical activity for different age groups; its Physical Activity for Everyone webpages include guidelines, instructional videos, and personal success stories
The UK National Health Service information source NHS Choices also explains the benefits of regular physical activity and includes physical activity guidelines, tips for exercising, and some personal stories
MedlinePlus has links to other resources about exercise and physical fitness (in English and Spanish)
doi:10.1371/journal.pmed.1001335
PMCID: PMC3491006  PMID: 23139642
3.  Impact of Weight Loss on Physical Function with Changes in Strength, Muscle Mass, and Muscle Fat Infiltration in Overweight to Moderately Obese Older Adults: A Randomized Clinical Trial 
Journal of Obesity  2010;2011:516576.
Purpose. Evaluate the effects of weight loss on muscle mass and area, muscle fat infiltration, strength, and their association with physical function. Methods. Thirty-six overweight to moderately obese, sedentary older adults were randomized into either a physical activity plus weight loss (PA+WL) or physical activity plus successful aging health education (PA+SA) program. Measurements included body composition by dual-energy X-ray absorptiometry, computerized tomography, knee extensor strength, and short physical performance battery (SPPB). Results. At 6 months, PA+WL lost greater thigh fat and muscle area compared to PA+SA. PA+WL lost 12.4% strength; PA+SA lost 1.0%. Muscle fat infiltration decreased significantly in PA+WL and PA+SA. Thigh fat area decreased 6-fold in comparison to lean area in PA+WL. Change in total SPPB score was strongly inversely correlated with change in fat but not with change in lean or strength. Conclusion. Weight loss resulted in additional improvements in function over exercise alone, primarily due to loss of body fat.
doi:10.1155/2011/516576
PMCID: PMC2952914  PMID: 20953373
4.  Effect of a Nutrition Supplement and Physical Activity Program on Pneumonia and Walking Capacity in Chilean Older People: A Factorial Cluster Randomized Trial 
PLoS Medicine  2011;8(4):e1001023.
Alan Dangour and colleagues report results from the CENEX (Cost-effectiveness Evaluation of a Nutritional supplement and EXercise program for older people) trial, which evaluates a nutritional and exercise program aiming to prevent pneumonia and physical decline in Chilean people.
Background
Ageing is associated with increased risk of poor health and functional decline. Uncertainties about the health-related benefits of nutrition and physical activity for older people have precluded their widespread implementation. We investigated the effectiveness and cost-effectiveness of a national nutritional supplementation program and/or a physical activity intervention among older people in Chile.
Methods and Findings
We conducted a cluster randomized factorial trial among low to middle socioeconomic status adults aged 65–67.9 years living in Santiago, Chile. We randomized 28 clusters (health centers) into the study and recruited 2,799 individuals in 2005 (∼100 per cluster). The interventions were a daily micronutrient-rich nutritional supplement, or two 1-hour physical activity classes per week, or both interventions, or neither, for 24 months. The primary outcomes, assessed blind to allocation, were incidence of pneumonia over 24 months, and physical function assessed by walking capacity 24 months after enrolment. Adherence was good for the nutritional supplement (∼75%), and moderate for the physical activity intervention (∼43%). Over 24 months the incidence rate of pneumonia did not differ between intervention and control clusters (32.5 versus 32.6 per 1,000 person years respectively; risk ratio = 1.00; 95% confidence interval 0.61–1.63; p = 0.99). In intention-to-treat analysis, after 24 months there was a significant difference in walking capacity between the intervention and control clusters (mean difference 33.8 meters; 95% confidence interval 13.9–53.8; p = 0.001). The overall cost of the physical activity intervention over 24 months was US$164/participant; equivalent to US$4.84/extra meter walked. The number of falls and fractures was balanced across physical activity intervention arms and no serious adverse events were reported for either intervention.
Conclusions
Chile's nutritional supplementation program for older people is not effective in reducing the incidence of pneumonia. This trial suggests that the provision of locally accessible physical activity classes in a transition economy population can be a cost-effective means of enhancing physical function in later life.
Trial registration
Current Controlled Trials ISRCTN 48153354
Please see later in the article for the Editors' Summary
Editors' Summary
Background
By 2050, about a quarter of the world's population will be aged 60 years or over, with Asia and Latin America experiencing the most dramatic increases in the proportion of older people. For example, in Chile, which has recently undergone rapid demographic transition, the proportion of the population aged 60 years or over has increased from 8% to 12% over the past 25 years.
Current global policy initiatives that promote healthy ageing include an emphasis on adequate nutrient intakes, as longitudinal studies (conducted in high-income countries) suggest that achieving nutritional sufficiency and maintaining moderate levels of physical activity both decrease risk of mortality by preserving immune function and lean body mass and so reduce the numerous risk factors for disability and chronic disease in later life. Such interventions may also decrease the risk of infection, particularly pneumonia, a common cause of death in older people. However, older people in low- and middle-income countries frequently have diets with insufficient calories (energy) and/or micronutrients.
Why Was This Study Done?
Currently, there is no high-quality evidence to support the benefits of improved nutrition and increased physical activity levels from low-income or transition economies, where the ongoing demographic trends suggest that the needs are greatest. National policies aimed at preserving health and function in older people with interventions such as cash-transfers and provision of “food baskets” are often used in Latin American countries, such as Chile, but are rarely formally evaluated. Therefore, the purpose of this study (the Cost-effectiveness Evaluation of a Nutritional supplement and EXercise program for older people—CENEX) was to evaluate Chile's national nutritional supplementation program and/or physical exercise, to investigate whether this program prevented pneumonia and physical functional decline in older people in Santiago, and also to investigate whether these interventions were cost-effective.
What Did the Researchers Do and Find?
The researchers randomly allocated 28 participating health centers in Santiago, Chile, into one of four arms: (1) nutritional supplementation; (2) nutritional supplementation+physical activity; (3) physical activity alone; (4) control. From May to December 2005, 2,799 eligible adults aged 65–67.9 years and living in low to middle socioeconomic circumstances, who attended each health center, were recruited into the study and received the allocated intervention—daily micronutrient-rich nutritional supplement, or two 1-hour physical activity classes per week, or both interventions or neither—for 24 months. The researchers did not know the allocation arm of each patient and over the course of the study assessed the incidence of pneumonia (viral and bacterial as based on diagnosis at the health center or hospital) and physical function was measured by walking capacity (meters walked in 6 minutes). The researchers used administrative records and interviews with staff and patients to estimate the cost-effectiveness of the interventions.
Participant retention in the study was 84%, although only three-quarters of patients receiving the nutritional intervention and less than half (43%) of patients in the physical activity intervention arm adhered to their respective programs. Over 24 months, the incidence rate of pneumonia did not differ between intervention and control groups (32.5 versus 32.6 per 1,000 person years, respectively), but at the end of the study period, there was a significant difference in walking capacity between the intervention and control clusters (mean difference 33.8 meters). The number of falls and fractures in the study arms were similar. The overall costs over 24 months were US$91.00 and US$163.70 per participant for the nutritional supplement and physical activity interventions, respectively. The cost of the physical activity intervention per extra meter walked at 24 months was US$4.84.
What Do These Findings Mean?
The results of this trial suggest that there is little evidence to support the effectiveness of Chile's national nutritional supplementation program in reducing the incidence of pneumonia for 65.0–67.9 year olds. Therefore, given Chile's high burden of infectious and nutrition-related chronic diseases and the associated high health costs, this program should not be considered as a priority preventive public health intervention. However, the provision of locally available physical activity classes to older people could be of clinical benefit, especially in urban settings such as Santiago, although future challenges include increasing the uptake of, and retention to, such programs.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001023.
The World Health Organization provides information about the state of health in Chile
Wikipedia also provides information about health and health care in Chile (please note that Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
doi:10.1371/journal.pmed.1001023
PMCID: PMC3079648  PMID: 21526229
5.  Muscle-Strengthening and Conditioning Activities and Risk of Type 2 Diabetes: A Prospective Study in Two Cohorts of US Women 
PLoS Medicine  2014;11(1):e1001587.
Anders Grøntved and colleagues examined whether women who perform muscle-strengthening and conditioning activities have an associated reduced risk of type 2 diabetes mellitus.
Please see later in the article for the Editors' Summary
Background
It is well established that aerobic physical activity can lower the risk of type 2 diabetes (T2D), but whether muscle-strengthening activities are beneficial for the prevention of T2D is unclear. This study examined the association of muscle-strengthening activities with the risk of T2D in women.
Methods and Findings
We prospectively followed up 99,316 middle-aged and older women for 8 years from the Nurses' Health Study ([NHS] aged 53–81 years, 2000–2008) and Nurses' Health Study II ([NHSII] aged 36–55 years, 2001–2009), who were free of diabetes, cancer, and cardiovascular diseases at baseline. Participants reported weekly time spent on resistance exercise, lower intensity muscular conditioning exercises (yoga, stretching, toning), and aerobic moderate and vigorous physical activity (MVPA) at baseline and in 2004/2005. Cox regression with adjustment for major determinants for T2D was carried out to examine the influence of these types of activities on T2D risk. During 705,869 person years of follow-up, 3,491 incident T2D cases were documented. In multivariable adjusted models including aerobic MVPA, the pooled relative risk (RR) for T2D for women performing 1–29, 30–59, 60–150, and >150 min/week of total muscle-strengthening and conditioning activities was 0.83, 0.93, 0.75, and 0.60 compared to women reporting no muscle-strengthening and conditioning activities (p<0.001 for trend). Furthermore, resistance exercise and lower intensity muscular conditioning exercises were each independently associated with lower risk of T2D in pooled analyses. Women who engaged in at least 150 min/week of aerobic MVPA and at least 60 min/week of muscle-strengthening activities had substantial risk reduction compared with inactive women (pooled RR = 0.33 [95% CI 0.29–0.38]). Limitations to the study include that muscle-strengthening and conditioning activity and other types of physical activity were assessed by a self-administered questionnaire and that the study population consisted of registered nurses with mostly European ancestry.
Conclusions
Our study suggests that engagement in muscle-strengthening and conditioning activities (resistance exercise, yoga, stretching, toning) is associated with a lower risk of T2D. Engagement in both aerobic MVPA and muscle-strengthening type activity is associated with a substantial reduction in the risk of T2D in middle-aged and older women.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Worldwide, more than 370 million people have diabetes mellitus, a disorder characterized by poor glycemic control—dangerously high amounts of glucose (sugar) in the blood. Blood sugar levels are normally controlled by insulin, a hormone released by the pancreas. In people with type 2 diabetes (the commonest form of diabetes), blood sugar control fails because the fat and muscle cells that normally respond to insulin by removing excess sugar from the blood become less responsive to insulin. Type 2 diabetes, which was previously known as adult-onset diabetes, can often initially be controlled with diet and exercise, and with antidiabetic drugs such as metformin and sulfonylureas. However, as the disease progresses, the pancreatic beta cells, which make insulin, become impaired and patients may eventually need insulin injections. Long-term complications of diabetes, which include an increased risk of cardiovascular problems such as heart disease and stroke, reduce the life expectancy of people with diabetes by about 10 years compared to people without diabetes.
Why Was This Study Done?
Type 2 diabetes is becoming increasingly common worldwide so better preventative strategies are essential. It is well-established that regular aerobic exercise—physical activity in which the breathing and heart rate increase noticeably such as jogging, brisk walking, and swimming—lowers the risk of type 2 diabetes. The World Health Organization currently recommends that adults should do at least 150 min/week of moderate-to-vigorous aerobic physical activity to reduce the risk of diabetes and other non-communicable diseases. It also recommends that adults should undertake muscle-strengthening and conditioning activities such as weight training and yoga on two or more days a week. However, although studies have shown that muscle-strengthening activity improves glycemic control in people who already have diabetes, it is unclear whether this form of exercise prevents diabetes. In this prospective cohort study (a study in which disease development is followed up over time in a group of people whose characteristics are recorded at baseline), the researchers investigated the association of muscle-strengthening activities with the risk of type 2 diabetes in women.
What Did the Researchers Do and Find?
The researchers followed up nearly 100,000 women enrolled in the Nurses' Health Study (NHS) and the Nurses' Health Study II (NHSII), two prospective US investigations into risk factors for chronic diseases in women, for 8 years. The women provided information on weekly participation in muscle-strengthening exercise (for example, weight training), lower intensity muscle-conditioning exercises (for example, yoga and toning), and aerobic moderate and vigorous physical activity (aerobic MVPA) at baseline and 4 years later. During the study 3,491 women developed diabetes. After allowing for major risk factors for type 2 diabetes (for example, diet and a family history of diabetes) and for aerobic MVPA, compared to women who did no muscle-strengthening or conditioning exercise, the risk of developing type 2 diabetes among women declined with increasing participation in muscle-strengthening and conditioning activity. Notably, women who did more than 150 min/week of these types of exercise had 40% lower risk of developing diabetes as women who did not exercise in this way at all. Muscle-strengthening and muscle-conditioning exercise were both independently associated with reduced diabetes risk, and women who engaged in at least 150 min/week of aerobic MVPA and at least 60 min/week of muscle-strengthening exercise were a third as likely to develop diabetes as inactive women.
What Do These Findings Mean?
These findings show that, among the women enrolled in NHS and NHSII, engagement in muscle-strengthening and conditioning activities lowered the risk of type 2 diabetes independent of aerobic MVPA. That is, non-aerobic exercise provided protection against diabetes in women who did no aerobic exercise. Importantly, they also show that doing both aerobic exercise and muscle-strengthening exercise substantially reduced the risk of type 2 diabetes. Because nearly all the participants in NHS and NHSII were of European ancestry, these results may not be generalizable to women of other ethnic backgrounds. Moreover, the accuracy of these findings may be limited by the use of self-administered questionnaires to determine how much exercise the women undertook. Nevertheless, these findings support the inclusion of muscle-strengthening and conditioning exercises in strategies designed to prevent type 2 diabetes in women, a conclusion that is consistent with current guidelines for physical activity among adults.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001587.
The US National Diabetes Information Clearinghouse provides information about diabetes for patients, health-care professionals and the general public, including information on diabetes prevention (in English and Spanish)
The UK National Health Service Choices website provides information for patients and carers about type 2 diabetes and explains the benefits of regular physical activity
The World Health Organization provides information about diabetes and about physical activity and health (in several languages); its 2010 Global Recommendations on Physical Activity for Health are available in several languages
The US Centers for Disease Control and Prevention provides information on physical activity for different age groups; its Physical Activity for Everyone web pages include guidelines, instructional videos and personal success stories
More information about the Nurses Health Study and the Nurses Health Study II is available
The UK charity Healthtalkonline has interviews with people about their experiences of diabetes
MedlinePlus provides links to further resources and advice about diabetes and about physical exercise and fitness (in English and Spanish)
doi:10.1371/journal.pmed.1001587
PMCID: PMC3891575  PMID: 24453948
6.  Associations between Active Travel to Work and Overweight, Hypertension, and Diabetes in India: A Cross-Sectional Study 
PLoS Medicine  2013;10(6):e1001459.
Using data from the Indian Migration Study, Christopher Millett and colleagues examine the associations between active travel to work and overweight, hypertension, and diabetes.
Please see later in the article for the Editors' Summary
Background
Increasing active travel (walking, bicycling, and public transport) is promoted as a key strategy to increase physical activity and reduce the growing burden of noncommunicable diseases (NCDs) globally. Little is known about patterns of active travel or associated cardiovascular health benefits in low- and middle-income countries. This study examines mode and duration of travel to work in rural and urban India and associations between active travel and overweight, hypertension, and diabetes.
Methods and Findings
Cross-sectional study of 3,902 participants (1,366 rural, 2,536 urban) in the Indian Migration Study. Associations between mode and duration of active travel and cardiovascular risk factors were assessed using random-effect logistic regression models adjusting for age, sex, caste, standard of living, occupation, factory location, leisure time physical activity, daily fat intake, smoking status, and alcohol use. Rural dwellers were significantly more likely to bicycle (68.3% versus 15.9%; p<0.001) to work than urban dwellers. The prevalence of overweight or obesity was 50.0%, 37.6%, 24.2%, 24.9%; hypertension was 17.7%, 11.8%, 6.5%, 9.8%; and diabetes was 10.8%, 7.4%, 3.8%, 7.3% in participants who travelled to work by private transport, public transport, bicycling, and walking, respectively. In the adjusted analysis, those walking (adjusted risk ratio [ARR] 0.72; 95% CI 0.58–0.88) or bicycling to work (ARR 0.66; 95% CI 0.55–0.77) were significantly less likely to be overweight or obese than those travelling by private transport. Those bicycling to work were significantly less likely to have hypertension (ARR 0.51; 95% CI 0.36–0.71) or diabetes (ARR 0.65; 95% CI 0.44–0.95). There was evidence of a dose-response relationship between duration of bicycling to work and being overweight, having hypertension or diabetes. The main limitation of the study is the cross-sectional design, which limits causal inference for the associations found.
Conclusions
Walking and bicycling to work was associated with reduced cardiovascular risk in the Indian population. Efforts to increase active travel in urban areas and halt declines in rural areas should be integral to strategies to maintain healthy weight and prevent NCDs in India.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Noncommunicable diseases (NCDs) and obesity (excessive body fat) are major threats to global health. Every year, more than 36 million people (including 29 million in LMICs) die from NCDs—nearly two-thirds of the world's annual deaths. Cardiovascular diseases (conditions that affect the heart and the circulation), diabetes, cancer, and respiratory diseases are responsible for most NCD-related deaths. Obesity is a risk factor for all these NCDs and the global prevalence of obesity (the proportion of the world's population that is obese) has nearly doubled since 1980. In 2008, 35% of adults were overweight and 11% were obese. One reason for the growing burden of both obesity and NCDs is increasing physical inactivity. Regular physical activity helps to maintain a healthy body weight and to prevent or delay the onset of NCDs. For an adult, 30 minutes of moderate physical activity—walking briskly or cycling, for example—five times a week is sufficient to promote and maintain health. But the daily lives of people in both developed and developing countries are becoming increasingly sedentary and, nowadays, at least 60% of the world's population does not do even this modest amount of exercise.
Why Was This Study Done?
Strategies to increase physical activity levels often promote active travel (walking, cycling, and using public transport). The positive impact of active travel on physical activity levels and cardiovascular health is well established in high-income countries, but little is known about the patterns of active travel or the health benefits associated with active travel in poorer countries. In this cross-sectional study (an investigation that measures population characteristics at a single time point), the researchers examine the mode and duration of travel to work in rural and urban India and associations between active travel and overweight/obesity, hypertension (high blood pressure, a risk factor for cardiovascular disease), and diabetes. In India, a lower middle-income country, the prevalence of overweight and NCDs is projected to increase rapidly over the next two decades. Moreover, rapid unplanned urbanization and a large increase in registered motor vehicles has resulted in inadequate development of the public transport infrastructure and hazardous conditions for walking and cycling in most Indian towns and cities.
What Did the Researchers Do and Find?
For their study, researchers analyzed physical activity and health data collected from participants in the Indian Migration Study, which examined the association between migration from rural to urban areas and obesity and diabetes risk. People living in rural areas were more likely to cycle to work than people living in towns and cities (68.3% versus 15.9%). Among people who travelled to work by private transport, public transport, walking, and cycling, the prevalence of overweight or obesity was 50.0%, 37.6%, 24.9%, and 24.2%, respectively. Similar patterns were seen for the prevalence of hypertension and diabetes. After adjustment for factors that affect the risk of obesity, hypertension, and diabetes (for example, daily fat intake and leisure time physical activity), people walking or cycling to work were less likely to be overweight or obese than those travelling by public transport, and those cycling to walk were less likely to have hypertension or diabetes. Finally, people with long cycle rides to work had a lower risk of being overweight or having hypertension or diabetes than people with short cycle rides.
What Do These Findings Mean?
These findings suggest that, as in high-income settings, walking and cycling to work are associated with a reduced risk of cardiovascular disease in India. Because this was a cross-sectional study, these findings do not prove that active travel reduces the risk of cardiovascular disease—people who cycle to work may share other unknown characteristics that are actually responsible for their reduced risk of cardiovascular disease. Moreover, this study did not consider non-cardiovascular outcomes associated with active travel that might affect health such as increased exposure to air pollution. Nevertheless, these findings suggest that programs designed to maintain healthy weight and prevent NCDs in India should endeavor to increase active travel in urban areas and to halt declines in rural areas by, for example, increasing investment in public transport and improving the safety and convenience of walking and cycling routes in urban areas.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001459.
This study is further discussed in a PLOS Medicine Perspective by Kavi Bhalla
The US Centers for Disease Control and Prevention provides information on all aspects of healthy living, on chronic diseases and health promotion, on overweight and obesity and on non-communicable diseases around the world; its Physical Activity for Everyone web pages include guidelines, instructional videos and personal success stories (some information in English and Spanish)
The World Health Organization provides information about physical activity and health, about obesity, and about non-communicable diseases (in several languages); its 2010 Global Recommendations on Physical Activity for Health are available in several languages; its Global Noncommunicable Disease Network (NCDnet) aims to help low- and middle- income countries reduce NCD-related illnesses and death through implementation of the 20082013 Action Plan for the Global Strategy for the Prevention and Control of Noncommunicable Diseases (also available in French); Face to face with chronic diseases is a selection of personal stories from around the world about dealing with NCDs
The American Heart Association provides information on many important risk factors for non-communicable diseases and provides tips for becoming more active
Information about the Indian Migration Study is available
doi:10.1371/journal.pmed.1001459
PMCID: PMC3679004  PMID: 23776412
7.  Weight Loss, Exercise, or Both and Physical Function in Obese Older Adults 
The New England journal of medicine  2011;364(13):1218-1229.
BACKGROUND
Obesity exacerbates the age-related decline in physical function and causes frailty in older adults; however, the appropriate treatment for obese older adults is controversial.
METHODS
In this 1-year, randomized, controlled trial, we evaluated the independent and combined effects of weight loss and exercise in 107 adults who were 65 years of age or older and obese. Participants were randomly assigned to a control group, a weightmanagement (diet) group, an exercise group, or a weight-management-plus-exercise (diet–exercise) group. The primary outcome was the change in score on the modified Physical Performance Test. Secondary outcomes included other measures of frailty, body composition, bone mineral density, specific physical functions, and quality of life.
RESULTS
A total of 93 participants (87%) completed the study. In the intention-to-treat analysis, the score on the Physical Performance Test, in which higher scores indicate better physical status, increased more in the diet–exercise group than in the diet group or the exercise group (increases from baseline of 21% vs. 12% and 15%, respectively); the scores in all three of those groups increased more than the scores in the control group (in which the score increased by 1%) (P<0.001 for the between-group differences). Moreover, the peak oxygen consumption improved more in the diet–exercise group than in the diet group or the exercise group (increases of 17% vs. 10% and 8%, respectively; P<0.001); the score on the Functional Status Questionnaire, in which higher scores indicate better physical function, increased more in the diet–exercise group than in the diet group (increase of 10% vs. 4%, P<0.001). Body weight decreased by 10% in the diet group and by 9% in the diet–exercise group, but did not decrease in the exercise group or the control group (P<0.001). Lean body mass and bone mineral density at the hip decreased less in the diet–exercise group than in the diet group (reductions of 3% and 1%, respectively, in the diet–exercise group vs. reductions of 5% and 3%, respectively, in the diet group; P<0.05 for both comparisons). Strength, balance, and gait improved consistently in the diet–exercise group (P<0.05 for all comparisons). Adverse events included a small number of exercise-associated musculoskeletal injuries.
CONCLUSIONS
These findings suggest that a combination of weight loss and exercise provides greater improvement in physical function than either intervention alone.
doi:10.1056/NEJMoa1008234
PMCID: PMC3114602  PMID: 21449785
8.  The influence of exercise and BMI on injuries and illnesses in overweight and obese individuals: a randomized control trial 
Background
Medically treated injuries have been shown to increase with increasing body mass index (BMI). Information is lacking on the frequency and type of injuries and illnesses among overweight and obese adults who engage in regular physical activities as part of weight loss or weight gain prevention programs.
Methods
Sedentary adults with BMIs between 25 and 40 kg/m2 (n = 397) enrolled in one of two randomized clinical trials that emphasized exercise as part of a weight loss or weight gain prevention program. Interventions differed by duration of the exercise goal (150, 200, or 300 minutes/week or control group). Walking was prescribed as the primary mode of exercise. At six month intervals, participants were asked, "During the past six months, did you have any injury or illness that affected your ability to exercise?" Longitudinal models were used to assess the effects of exercise and BMI on the pattern of injuries/illnesses attributed to exercise over time; censored linear regression was used to identify predictors of time to first injury/illness attributed to exercise.
Results
During the 18-month study, 46% reported at least one injury/illness, and 32% reported at least one injury that was attributed to exercise. Lower-body musculoskeletal injuries (21%) were the most commonly reported injury followed by cold/flu/respiratory infections (18%) and back pain/injury (10%). Knee injuries comprised one-third of the lower-body musculoskeletal injuries. Only 7% of the injuries were attributed to exercise alone, and 59% of the injuries did not involve exercise. BMI (p ≤ 0.01) but not exercise (p ≥ 0.41) was significantly associated with time to first injury and injuries over time. Participants with higher BMIs were injured earlier or had increased odds of injury over time than participants with lower BMIs. Due to the linear dose-response relationship between BMI and injury/illness, any weight loss and reduction in BMI was associated with a decrease risk of injury/illness and delay in time to injury/illness.
Conclusions
Overweight and obese adults who were prescribed exercise as part of weight loss or weight gain prevention intervention were not at increased risk of injury compared to overweight adults randomized not to participate in prescribed exercise. Since onset of injury/illness and pattern of injuries over time in overweight and obese individuals were attributed to BMI, weight reduction may be an avenue to reduce the risk of injury/illness in sedentary and previously sedentary overweight and obese adults.
Trial Registration
Clinicaltrials.gov NCT00177502 and NCT00177476
doi:10.1186/1479-5868-7-1
PMCID: PMC2818622  PMID: 20145731
9.  Dose–response effects of exercise training on the subjective sleep quality of postmenopausal women: exploratory analyses of a randomised controlled trial 
BMJ Open  2012;2(4):e001044.
Objective
To investigate whether a dose–response relationship existed between exercise and subjective sleep quality in postmenopausal women. This objective represents a post hoc assessment that was not previously considered.
Design
Parallel-group randomised controlled trial.
Setting
Clinical exercise physiology laboratory in Dallas, Texas.
Participants
437 sedentary overweight/obese postmenopausal women.
Intervention
Participants were randomised to one of four treatments, each of 6 months of duration: a non-exercise control treatment (n=92) or one of three dosages of moderate-intensity exercise (50% of VO2peak), designed to meet 50% (n=151), 100% (n=99) or 150% (n=95) of the National Institutes of Health Consensus Development Panel physical activity recommendations. Exercise dosages were structured to elicit energy expenditures of 4, 8 or 12 kilocalories per kilogram of body weight per week (KKW), respectively. Analyses were intent to treat.
Primary outcome measures
Continuous scores and odds of having significant sleep disturbance, as assessed by the Sleep Problems Index from the 6-item Medical Outcomes Study Sleep Scale. Outcome assessors were blinded to participant randomisation assignment.
Results
Change in the Medical Outcomes Study Sleep Problems Index score at 6 months significantly differed by treatment group (control: −2.09 (95% CI −4.58 to 0.40), 4 KKW: −3.93 (−5.87 to −1.99), 8 KKW: −4.06 (−6.45 to −1.67), 12 KKW: −6.22 (−8.68 to −3.77); p=0.04), with a significant dose–response trend observed (p=0.02). Exercise training participants had lower odds of having significant sleep disturbance at postintervention compared with control (4 KKW: OR 0.37 (95% CI 0.19 to 0.73), 8 KKW: 0.36 (0.17 to 0.77), 12 KKW: 0.34 (0.16 to 0.72)). The magnitude of weight loss did not differ between treatment conditions. Improvements in sleep quality were not related to changes in body weight, resting parasympathetic control or cardiorespiratory fitness.
Conclusion
Exercise training induced significant improvement in subjective sleep quality in postmenopausal women, with even a low dose of exercise resulting in greatly reduced odds of having significant sleep disturbance.
Trial registration number
clinicaltrials.gov identifier: NCT00011193.
Article summary
Article focus
Sleep disturbance is prevalent in postmenopausal women, with 35%–60% reporting significant sleep problems.
Effective, safe and easily available treatment options for disturbed sleep in postmenopausal women are lacking.
There has been equivocal evidence as to whether exercise improves sleep in postmenopausal women, though possible dose–response effects have been noted.
Key messages
Exercise resulted in significant improvement in subjective sleep quality in postmenopausal women, with reduced odds of having sleep disturbance at postintervention with even 50% of the recommended dose of exercise for adults.
The effects of exercise on sleep quality were independent of changes in body weight, resting parasympathetic control or cardiorespiratory fitness.
Strengths and limitations of this study
The study constitutes the largest randomised controlled trial on exercise and sleep quality, using a structured dose of exercise and a validated measure of sleep quality.
Only self-reported sleep was assessed; objective measurement of sleep, with either actigraphy or polysomnography, was not conducted.
Despite the high prevalence of sleep disturbance in the sample, participants were not selected on the basis of sleep complaints.
doi:10.1136/bmjopen-2012-001044
PMCID: PMC3400065  PMID: 22798253
10.  Tablet-Based Strength-Balance Training to Motivate and Improve Adherence to Exercise in Independently Living Older People: Part 2 of a Phase II Preclinical Exploratory Trial 
Background
Home-based exercise programs can improve physical functioning and health status of elderly people. Successful implementation of exercise interventions for older people presents major challenges and supporting elderly people properly while doing their home-based exercises is essential for training success. We developed a tablet-based system—ActiveLifestyle—that offers older adults a home-based strength-balance training program with incorporated motivation strategies and support features.
Objective
The goal was to compare 3 different home-based training programs with respect to their effect on measures of gait quality and physical performance through planned comparisons between (1) tablet-based and brochure-based interventions, (2) individual and social motivation strategies, and (3) active and inactive participants.
Methods
A total of 44 autonomous-living elderly people (mean 75, SD 6 years) were assigned to 3 training groups: social (tablet guided, n=14), individual (tablet guided, n=13), and brochure (brochure guided, n=17). All groups joined a 12-week progressive home-based strength-balance training program. Outcome measures were gait performance under single and dual task conditions, dual task costs of walking, falls efficacy, and physical performance as measured by the Short Physical Performance Battery (SPPB). Furthermore, active (≥75% program compliance) and inactive (<75% program compliance) individuals were compared based on their characteristics and outcome measures.
Results
The tablet groups showed significant improvements in single and dual task walking, whereas there were no significant changes observable in the brochure group. Between-groups comparisons revealed significant differences for gait velocity (U=138.5; P=.03, r=.33) and cadence (U=138.5, P=.03 r=.34) during dual task walking at preferred speed in favor of the tablet groups. The brochure group had more inactive participants, but this did not reach statistical significance (U=167, P=.06, r=.29). The active participants outperformed the inactive participants in single and dual task walking, dual task costs of walking, and SPPB scores. Significant between-groups differences were seen between the tablet groups and the brochure group, in favor of the tablet groups.
Conclusions
A tablet-based strength-balance training program that allows monitoring and assisting autonomous-living older adults while training at home was more effective in improving gait and physical performance when compared to a brochure-based program. Social or individual motivation strategies were equally effective. The most prominent differences were observed between active and inactive participants. These findings suggest that in older adults a tablet-based intervention enhances training compliance; hence, it is an effective way to improve gait.
doi:10.2196/jmir.3055
PMCID: PMC4090377  PMID: 24966165
gait; aging; exercise therapy; tablet; delivery of health care
11.  Combined Aerobic and Resistance Exercise Program Improves Task Performance in Patients With Heart Failure 
Objectives
To assess the effects of a home-based aerobic and resistance training program on the physical function of adults with New York Heart Association (NYHA) class II and III patients and systolic heart failure (HF).
Design
Randomized controlled trial.
Setting
Home based.
Participants
Stable patients (N=24; mean age, 60±10y; left ventricular ejection fraction, 25%±9%; 50% white; 50% women) with New York Heart Association (NYHA) classes II and III (NYHA class III, 58%) systolic heart failure (HF).
Intervention
A 12-week progressive home-based program of moderate-intensity aerobic and resistance exercise. Attention control wait list participants performed light stretching and flexibility exercises.
Main Outcome Measures
A 10-item performance-based physical function measure, the Continuous Scale Physical Functional Performance test (CS-PFP10), was the major outcome variable and included specific physical activities measured in time to complete a task, weight carried during a task, and distance walked. Other measures included muscle strength, HRQOL (Minnesota Living With Heart Failure Questionnaire, Epworth Sleepiness Scale), functional capacity (Duke Activity Status Index), and disease severity (brain natriuretic peptide) levels.
Results
After the exercise intervention, 9 of 10 specific task activities were performed more rapidly, with increased weight carried by exercise participants compared with the attention control wait list group. Exercise participants also showed significant improvements in CS-PFP10 total score (P<.025), upper and lower muscle strength, and HRQOL (P<.001) compared with the attention control wait list group. Adherence rates were 83% and 99% for the aerobic and resistance training, respectively.
Conclusions
Patients with stable HF who participate in a moderate-intensity combined aerobic and resistance exercise program may improve performance of routine physical activities of daily living by using a home-based exercise approach. Performance-based measures such as the CS-PFP10 may provide additional insights into physical function in patients with HF that more commonly used exercise tests may not identify. Early detection of subtle changes that may signal declining physical function that are amenable to intervention potentially may slow further loss of function in this patient population.
doi:10.1016/j.apmr.2011.02.022
PMCID: PMC4143394  PMID: 21878207
Exercise; Functional performance measures; Health-related quality of life; Heart failure; Rehabilitation
12.  Weight Loss and Psychologic Gain in Obese Women—Participants in a Supported Exercise Intervention 
The Permanente Journal  2008;12(3):36-45.
Background: Physical activity is a predictor of maintained weight loss; however, causal mechanisms are unclear. Behavioral theories suggest that associated psychologic changes may indirectly affect weight loss.
Objective: We sought to test the association of a behaviorally based exercise support protocol (The Coach Approach [CA]), with and without a group-based nutrition education program (Cultivating Health), with adherence to exercise and changes in physiologic and psychologic factors, and to assess theory-based paths to weight and body-fat changes.
Setting: The study took place in YMCA wellness centers.
Study subjects: Study participation was open to formerly sedentary obese women.
Design: Study participants were randomly assigned to the CA Only (CA; n = 81), The CA Plus Cultivating Health (CA/CH; n = 128), or the control (n = 64) group. We contrasted dropout and attendance rates and changes in self-efficacy (SE), physical self-concept (PSC), total mood disturbance (TMD), body areas satisfaction (BAS), and select physiologic factors during a six-month period. We also analyzed proposed paths to weight loss.
Results: The CA and CA/CH groups had significantly lower exercise dropout rates (χ2 = 44.67, p < 0.001) and higher attendance rates (F = 10.02; p < 0.001) than the control group did. Improvements in body fat, body mass index (BMI), and waist circumference were significant for only the CA and CA/CH groups. Significant improvements in TMD, PSC, and BAS scores were found for all groups, with effect sizes greater in the groups incorporating the CA protocol. Within the five paths assessed, entry of changes in TMD and BAS scores into multiple-regression equations, along with SE and PSC scores, increased the explained variance in exercise session attendance from 5% (p = 0.01) to 16% (p < 0.001). Exercise session attendance was significantly associated with changes in body fat (r = −0.41; p < 0.001) and BMI (r = −0.46; p < 0.001).
Conclusion: Counseling based on social cognitive and self-efficacy theory may increase exercise adherence and improve variables indirectly related to weight and body-fat reductions. Although decreases in body fat and BMI were obtained, they appeared less pronounced than psychologic improvements. Additional research on interrelations of physical activity, psychologic factors, and weight change is warranted for development of obesity treatments.
PMCID: PMC3037122  PMID: 21331208
13.  Land-based versus aquatic resistance therapeutic exercises for older women with sarcopenic obesity: study protocol for a randomised controlled trial 
Trials  2013;14:296.
Background
Sarcopenic obesity is a health condition that combines excess adipose tissue and loss of muscle mass and strength. Sarcopenic obesity predisposes to more functional disabilities than obesity or sarcopenia alone. Progressive resistance exercises are recommended for older people as a potential treatment for sarcopenia and also for obesity. However, there is a lack of evidence indicating which programmes are best applied to older people, and no studies have investigated their effects on sarcopenic obese people. The aims of this protocol study are to investigate and compare the efficacy of land-based and aquatic resistance exercise programmes on improving muscle performance, functional capacity and quality of life of older women with sarcopenic obesity.
Methods/Design
This is a protocol study for a parallel randomised controlled clinical trial. Eligible participants are older women (≥65 years) with a body mass index ≥30 kg/m 2 and hand grip strength ≤21 kg force. A total sample of 36 participants will be randomly allocated to one of the intervention groups in blocks of three: land-based, aquatic or control. Each intervention group will undergo 2-week sessions of a 10-week therapeutic exercise programme for strength, power and endurance training of the lower-limb muscles. Participants in the control group will not participate in any strengthening activity for lower limbs and will receive telephone calls once a week. Baseline and final evaluation of outcomes will encompass muscle performance of the lower limbs assessed by an isokinetic dynamometer; functional tests of usual walking speed, maximal walking speed (shuttle walking test), stair speed and the Short Physical Performance Battery; and health-related quality of life (Medical Outcomes Study Short Form Questionnaire – SF-36). Data collectors will be blinded to randomisation and will not be in touch with participants during the interventions.
Discussion
This study is the first randomised controlled trial designed to evaluate resistance exercises in older patients with sarcopenic obesity. If our hypothesis proves correct, both intervention programmes will be effective, with the land-based exercises conferring better results in muscle performance.
Trial registration
Registro Brasileiro de Ensaios Clínicos: RBR-9p5q67
doi:10.1186/1745-6215-14-296
PMCID: PMC3848713  PMID: 24041219
Older people; Women; Sarcopenic obesity; Resistance exercises
14.  Assessing Causality in the Association between Child Adiposity and Physical Activity Levels: A Mendelian Randomization Analysis 
PLoS Medicine  2014;11(3):e1001618.
Here, Timpson and colleagues performed a Mendelian Randomization analysis to determine whether childhood adiposity causally influences levels of physical activity. The results suggest that increased adiposity causes a reduction in physical activity in children; however, this study does not exclude lower physical activity also leading to increasing adiposity.
Please see later in the article for the Editors' Summary
Background
Cross-sectional studies have shown that objectively measured physical activity is associated with childhood adiposity, and a strong inverse dose–response association with body mass index (BMI) has been found. However, few studies have explored the extent to which this association reflects reverse causation. We aimed to determine whether childhood adiposity causally influences levels of physical activity using genetic variants reliably associated with adiposity to estimate causal effects.
Methods and Findings
The Avon Longitudinal Study of Parents and Children collected data on objectively assessed activity levels of 4,296 children at age 11 y with recorded BMI and genotypic data. We used 32 established genetic correlates of BMI combined in a weighted allelic score as an instrumental variable for adiposity to estimate the causal effect of adiposity on activity.
In observational analysis, a 3.3 kg/m2 (one standard deviation) higher BMI was associated with 22.3 (95% CI, 17.0, 27.6) movement counts/min less total physical activity (p = 1.6×10−16), 2.6 (2.1, 3.1) min/d less moderate-to-vigorous-intensity activity (p = 3.7×10−29), and 3.5 (1.5, 5.5) min/d more sedentary time (p = 5.0×10−4). In Mendelian randomization analyses, the same difference in BMI was associated with 32.4 (0.9, 63.9) movement counts/min less total physical activity (p = 0.04) (∼5.3% of the mean counts/minute), 2.8 (0.1, 5.5) min/d less moderate-to-vigorous-intensity activity (p = 0.04), and 13.2 (1.3, 25.2) min/d more sedentary time (p = 0.03). There was no strong evidence for a difference between variable estimates from observational estimates. Similar results were obtained using fat mass index. Low power and poor instrumentation of activity limited causal analysis of the influence of physical activity on BMI.
Conclusions
Our results suggest that increased adiposity causes a reduction in physical activity in children and support research into the targeting of BMI in efforts to increase childhood activity levels. Importantly, this does not exclude lower physical activity also leading to increased adiposity, i.e., bidirectional causation.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The World Health Organization estimates that globally at least 42 million children under the age of five are obese. The World Health Organization recommends that all children undertake at least one hour of physical activity daily, on the basis that increased physical activity will reduce or prevent excessive weight gain in children and adolescents. In practice, while numerous studies have shown that body mass index (BMI) shows a strong inverse correlation with physical activity (i.e., active children are thinner than sedentary ones), exercise programs specifically targeted at obese children have had only very limited success in reducing weight. The reasons for this are not clear, although environmental factors such as watching television and lack of exercise facilities are traditionally blamed.
Why Was This Study Done?
One of the reasons why obese children do not lose weight through exercise might be that being fat in itself leads to a decrease in physical activity. This is termed reverse causation, i.e., obesity causes sedentary behavior, rather than the other way around. The potential influence of environmental factors (e.g., lack of opportunity to exercise) makes it difficult to prove this argument. Recent research has demonstrated that specific genotypes are related to obesity in children. Specific variations within the DNA of individual genes (single nucleotide polymorphisms, or SNPs) are more common in obese individuals and predispose to greater adiposity across the weight distribution. While adiposity itself can be influenced by many environmental factors that complicate the interpretation of observed associations, at the population level, genetic variation is not related to the same factors, and over the life course cannot be changed. Investigations that exploit these properties of genetic associations to inform the interpretation of observed associations are termed Mendelian randomization studies. This research technique is used to reduce the influence of confounding environmental factors on an observed clinical condition. The authors of this study use Mendelian randomization to determine whether a genetic tendency towards high BMI and fat mass is correlated with reduced levels of physical activity in a large cohort of children.
What Did the Researchers Do and Find?
The researchers looked at a cohort of children from a large long-term health research project (the Avon Longitudinal Study of Parents and Children). BMI and total body fat were recorded. Total daily activity was measured via a small movement-counting device. In addition, the participants underwent genotyping to detect the presence of several SNPs known to be linked to obesity. For each child a total BMI allelic score was determined based on the number of obesity-related genetic variants carried by that individual. The association between obesity and reduced physical activity was then studied in two ways. Direct correlation between actual BMI and physical activity was measured (observational data). Separately, the link between BMI allelic score and physical activity was also determined (Mendelian randomization or instrumental variable analysis). The observational data showed that boys were more active than girls and had lower BMI. Across both sexes, a higher-than-average BMI was associated with lower daily activity. In genetic analyses, allelic score had a positive correlation with BMI, with one particular SNP being most strongly linked to high BMI and total fat mass. A high allelic score for BMI was also correlated with lower levels of daily physical activity. The authors conclude that children who are obese and have an inherent predisposition to high BMI also have a propensity to reduced levels of physical activity, which may compound their weight gain.
What Do These Findings Mean?
This study provides evidence that being fat is in itself a risk factor for low activity levels, separately from external environmental influences. This may be an example of “reverse causation,” i.e., high BMI causes a reduction in physical activity. Alternatively, there may be a bidirectional causality, so that those with a genetic predisposition to high fat mass exercise less, leading to higher BMI, and so on, in a vicious circle. A significant limitation of the study is that validated allelic scores for physical activity are not available. Thus, it is not possible to determine whether individuals with a high allelic score for BMI also have a propensity to exercise less, or whether it is simply the circumstance of being overweight that discourages activity. This study does suggest that trying to persuade obese children to lose weight by exercising more is likely to be ineffective unless additional strategies to reduce BMI, such as strict diet control, are also implemented.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001618.
The US Centers for Disease Control and Prevention provides obesity-related statistics, details of prevention programs, and an overview on public health strategy in the United States
A more worldwide view is given by the World Health Organization
The UK National Health Service website gives information on physical activity guidelines for different age groups
The International Obesity Task Force is a network of organizations that seeks to alert the world to the growing health crisis threatened by soaring levels of obesity
MedlinePlus—which brings together authoritative information from the US National Library of Medicine, National Institutes of Health, and other government agencies and health-related organizations—has a page on obesity
Additional information on the Avon Longitudinal Study of Parents and Children is available
The British Medical Journal has an article that describes Mendelian randomization
doi:10.1371/journal.pmed.1001618
PMCID: PMC3958348  PMID: 24642734
15.  Effects of dietary intervention and quadriceps strengthening exercises on pain and function in overweight people with knee pain: randomised controlled trial 
Objective To determine whether dietary intervention or knee strengthening exercise, or both, can reduce knee pain and improve knee function in overweight and obese adults in the community.
Design Pragmatic factorial randomised controlled trial.
Setting Five general practices in Nottingham.
Participants 389 men and women aged 45 and over with a body mass index (BMI) of ≥28.0 and self reported knee pain.
Interventions Participants were randomised to dietary intervention plus quadriceps strengthening exercises; dietary intervention alone; quadriceps strengthening exercises alone; advice leaflet only (control group). Dietary intervention consisted of individualised healthy eating advice that would reduce normal intake by 2.5 MJ (600 kcal) a day. Interventions were delivered at home visits over a two year period.
Main outcome measures The primary outcome was severity of knee pain scored with the Western Ontario McMaster (WOMAC) osteoarthritis index at 6, 12, and 24 months. Secondary outcomes (all at 24 months) included WOMAC knee physical function and stiffness scores and selected domains on the SF-36 and the hospital anxiety and depression index.
Results 289 (74%) participants completed the trial. There was a significant reduction in knee pain in the knee exercise groups compared with those in the non-exercise groups at 24 months (percentage risk difference 11.61, 95% confidence interval 1.81% to 21.41%). The absolute effect size (0.25) was moderate. The number needed to treat to benefit from a ≥30% improvement in knee pain at 24 months was 9 (5 to 55). In those randomised to knee exercise improvement in function was evident at 24 months (mean difference −3.64, −6.01 to −1.27). The mean difference in weight loss at 24 months in the dietary intervention group compared with no dietary intervention was 2.95 kg (1.44 to 4.46); for exercise versus no exercise the difference was 0.43 kg (−0.82 to 1.68). This difference in weight loss was not associated with improvement in knee pain or function but was associated with a reduction in depression (absolute effect size 0.19).
Conclusions A home based, self managed programme of simple knee strengthening exercises over a two year period can significantly reduce knee pain and improve knee function in overweight and obese people with knee pain. A moderate sustained weight loss is achievable with dietary intervention and is associated with reduced depression but is without apparent influence on pain or function.
Trial registration Current Controlled Trials ISRCTN 93206785.
doi:10.1136/bmj.b3170
PMCID: PMC2728801  PMID: 19690345
16.  Influences of carbohydrate plus amino acid supplementation on differing exercise intensity adaptations in older persons: skeletal muscle and endocrine responses 
Age  2010;32(2):125-138.
Losses in physiological function in healthy ageing occur partly as a consequence of reduced protein intake and partly as a consequence of less than 30-min/day of moderate to vigorous physical activity. The current study aimed to compare the effects of two different intensities of resistance training in healthy older adults, whose habitual dietary intake was supplemented with carbohydrate and amino acid preparations. We hypothesised that although intensive exercise with appropriate carbohydrate and amino acid supplementation would result in the most profound impact on in vivo markers of healthy physiologic and endocrine functions in previously sedentary older individuals, the effectiveness of the less intense exercise prescription with supplementation would also result in beneficial adaptations over and above findings of previous studies on low intensity exercise alone. Twenty-nine older adults (out of 32) completed the study after being randomly assigned to low (SUP_LowR, i.e., ∼40% 1RM; n = 16) versus high resistance training (SUP_HighR, i.e., ∼80% 1RM; n = 13) for 12 weeks. A carbohydrate supplement was ingested immediately before and during every exercise session and an amino acid cocktail was ingested post-exercise. Neither intervention significantly impacted upon body composition assessed using: Body mass index, waist/hip ratio and bioelectric impedance. Muscle strength increased similarly in the two groups with the SUP_HighR protocol showing 46 ± 8%, 10.8 ± 4.4% and 26.9 ± 4.9% (P < 0.01) improvements in 1-RM strength, unilateral and bilateral knee extension torque, respectively, compared with 39 ± 2%, 9.4 ± 3.7% and 29.5 ± 8.2% (P < 0.01) increments in the same measures in the SUP_LowR group. Lean muscle thickness however, showed a greater benefit of the SUP_LowR protocol (8.7 ± 3.9% increase, P < 0.05) compared with the SUP_HighR protocol, which elicited no significant change. In terms of functional abilities, only the standing-from-lying (SFL) test exhibited an improvement in rate in the SUP_HighR group (−11.4%, P < 0.05). The SUP_LowR group, on the other hand, showed significant improvements in the get-up-and-go (−8.7 ± 3.6%, P < 0.05), the SFL (−4.7% change, P = 0.05) and the 6-min walk (7.2 ± 2.2% increase in distance covered, P < 0.01) tests. Following overnight fasting, serum levels of glucose changed significantly (−13 ± 4.7% decrease, P < 0.01) in SUP_LowR. Serum levels of insulin (−25 ± 5.3% decrease, P = 0.05), neuropeptide Y (−24 ± 15.3% decrease, P = 0.02), and IGFBP-3 (−11 ± 6.6% decrease, P = 0.03), changed significantly in SUP_HighR. Circulating levels of interleukin-6, tumour necrosis factor-alpha and insulin-like growth factor 1 did not alter significantly in either intervention group. These data suggest that whilst both interventions were beneficial in older persons, the end targets as well as metabolic and hormonal adaptations are different. The supplementation plus low exercise regimen tended to impact on muscle hypertrophy combined with increased habitual function. Supplementation plus high-intensity exercise regimen improved markers of strength, but not to a significantly greater extent than supplementation plus low intensity exercise.
doi:10.1007/s11357-009-9129-9
PMCID: PMC2861756  PMID: 20431985
Elderly; Endocrinology; Cytokines; Physiology; Resistance exercise intensity; Nutritional supplementation
17.  Computerized Cognitive Training in Cognitively Healthy Older Adults: A Systematic Review and Meta-Analysis of Effect Modifiers 
PLoS Medicine  2014;11(11):e1001756.
Michael Valenzuela and colleagues systematically review and meta-analyze the evidence that computerized cognitive training improves cognitive skills in older adults with normal cognition.
Please see later in the article for the Editors' Summary
Background
New effective interventions to attenuate age-related cognitive decline are a global priority. Computerized cognitive training (CCT) is believed to be safe and can be inexpensive, but neither its efficacy in enhancing cognitive performance in healthy older adults nor the impact of design factors on such efficacy has been systematically analyzed. Our aim therefore was to quantitatively assess whether CCT programs can enhance cognition in healthy older adults, discriminate responsive from nonresponsive cognitive domains, and identify the most salient design factors.
Methods and Findings
We systematically searched Medline, Embase, and PsycINFO for relevant studies from the databases' inception to 9 July 2014. Eligible studies were randomized controlled trials investigating the effects of ≥4 h of CCT on performance in neuropsychological tests in older adults without dementia or other cognitive impairment. Fifty-two studies encompassing 4,885 participants were eligible. Intervention designs varied considerably, but after removal of one outlier, heterogeneity across studies was small (I2 = 29.92%). There was no systematic evidence of publication bias. The overall effect size (Hedges' g, random effects model) for CCT versus control was small and statistically significant, g = 0.22 (95% CI 0.15 to 0.29). Small to moderate effect sizes were found for nonverbal memory, g = 0.24 (95% CI 0.09 to 0.38); verbal memory, g = 0.08 (95% CI 0.01 to 0.15); working memory (WM), g = 0.22 (95% CI 0.09 to 0.35); processing speed, g = 0.31 (95% CI 0.11 to 0.50); and visuospatial skills, g = 0.30 (95% CI 0.07 to 0.54). No significant effects were found for executive functions and attention. Moderator analyses revealed that home-based administration was ineffective compared to group-based training, and that more than three training sessions per week was ineffective versus three or fewer. There was no evidence for the effectiveness of WM training, and only weak evidence for sessions less than 30 min. These results are limited to healthy older adults, and do not address the durability of training effects.
Conclusions
CCT is modestly effective at improving cognitive performance in healthy older adults, but efficacy varies across cognitive domains and is largely determined by design choices. Unsupervised at-home training and training more than three times per week are specifically ineffective. Further research is required to enhance efficacy of the intervention.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
As we get older, we notice many bodily changes. Our hair goes grey, we develop new aches and pains, and getting out of bed in the morning takes longer than it did when we were young. Our brain may also show signs of aging. It may take us longer to learn new information, we may lose our keys more frequently, and we may forget people's names. Cognitive decline—developing worsened thinking, language, memory, understanding, and judgment—can be a normal part of aging, but it can also be an early sign of dementia, a group of brain disorders characterized by a severe, irreversible decline in cognitive functions. We know that age-related physical decline can be attenuated by keeping physically active; similarly, engaging in activities that stimulate the brain throughout life is thought to enhance cognition in later life and reduce the risk of age-related cognitive decline and dementia. Thus, having an active social life and doing challenging activities that stimulate both the brain and the body may help to stave off cognitive decline.
Why Was This Study Done?
“Brain training” may be another way of keeping mentally fit. The sale of computerized cognitive training (CCT) packages, which provide standardized, cognitively challenging tasks designed to “exercise” various cognitive functions, is a lucrative and expanding business. But does CCT work? Given the rising global incidence of dementia, effective interventions that attenuate age-related cognitive decline are urgently needed. However, the impact of CCT on cognitive performance in older adults is unclear, and little is known about what makes a good CCT package. In this systematic review and meta-analysis, the researchers assess whether CCT programs improve cognitive test performance in cognitively healthy older adults and identify the aspects of cognition (cognitive domains) that are responsive to CCT, and the CCT design features that are most important in improving cognitive performance. A systematic review uses pre-defined criteria to identify all the research on a given topic; meta-analysis uses statistical methods to combine the results of several studies.
What Did the Researchers Do and Find?
The researchers identified 51 trials that investigated the effects of more than four hours of CCT on nearly 5,000 cognitively healthy older adults by measuring several cognitive functions before and after CCT. Meta-analysis of these studies indicated that the overall effect size for CCT (compared to control individuals who did not participate in CCT) was small but statistically significant. An effect size quantifies the difference between two groups; a statistically significant result is a result that is unlikely to have occurred by chance. So, the meta-analysis suggests that CCT slightly increased overall cognitive function. Notably, CCT also had small to moderate significant effects on individual cognitive functions. For example, some CCT slightly improved nonverbal memory (the ability to remember visual images) and working memory (the ability to remember recent events; short-term memory). However, CCT had no significant effect on executive functions (cognitive processes involved in planning and judgment) or attention (selective concentration on one aspect of the environment). The design of CCT used in the different studies varied considerably, and “moderator” analyses revealed that home-based CCT was not effective, whereas center-based CCT was effective, and that training sessions undertaken more than three times a week were not effective. There was also some weak evidence suggesting that CCT sessions lasting less than 30 minutes may be ineffective. Finally, there was no evidence for the effectiveness of working memory training by itself (for example, programs that ask individuals to recall series of letters).
What Do These Findings Mean?
These findings suggest that CCT produces small improvements in cognitive performance in cognitively healthy older adults but that the efficacy of CCT varies across cognitive domains and is largely determined by design aspects of CCT. The most important result was that “do-it-yourself” CCT at home did not produce improvements. Rather, the small improvements seen were in individuals supervised by a trainer in a center and undergoing sessions 1–3 times a week. Because only cognitively healthy older adults were enrolled in the studies considered in this systematic review and meta-analysis, these findings do not necessarily apply to cognitively impaired individuals. Moreover, because all the included studies measured cognitive function immediately after CCT, these findings provide no information about the durability of the effects of CCT or about how the effects of CCT on cognitive function translate into real-life outcomes for individuals such as independence and the long-term risk of dementia. The researchers call, therefore, for additional research into CCT, an intervention that might help to attenuate age-related cognitive decline and improve the quality of life for older individuals.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001756.
This study is further discussed in a PLOS Medicine Perspective by Druin Burch
The US National Institute on Aging provides information for patients and carers about age-related forgetfulness, about memory and cognitive health, and about dementia (in English and Spanish)
The UK National Health Service Choices website also provides information about dementia and about memory loss
MedlinePlus provides links to additional resources about memory, mild cognitive impairment, and dementia (in English and Spanish)
doi:10.1371/journal.pmed.1001756
PMCID: PMC4236015  PMID: 25405755
18.  An Exploratory Analysis of the Effects of a Weight Loss Plus Exercise Program on Cellular Quality Control Mechanisms in Older Overweight Women 
Rejuvenation Research  2011;14(3):315-324.
Abstract
Obese older adults are particularly susceptible to sarcopenia and have a higher prevalence of disability than their peers of normal weight. Interventions to improve body composition in late life are crucial to maintaining independence. The main mechanisms underlying sarcopenia have not been determined conclusively, but chronic inflammation, apoptosis, and impaired mitochondrial function are believed to play important roles. It has yet to be determined whether impaired cellular quality control mechanisms contribute to this process. The objective of this study was to assess the effects of a 6-month weight loss program combined with moderate-intensity exercise on the cellular quality control mechanisms autophagy and ubiquitin-proteasome, as well as on inflammation, apoptosis, and mitochondrial function, in the skeletal muscle of older obese women. The intervention resulted in significant weight loss (8.0 ± 3.9 % vs. 0.4 ± 3.1% of baseline weight, p = 0.002) and improvements in walking speed (reduced time to walk 400 meters, − 20.4 ± 16% vs. − 2.5 ± 12%, p = 0.03). In the intervention group, we observed a three-fold increase in messenger RNA (mRNA) levels of the autophagy regulators LC3B, Atg7, and lysosome-associated membrane protein-2 (LAMP-2) compared to controls. Changes in mRNA levels of FoxO3A and its targets MuRF1, MAFBx, and BNIP3 were on average seven-fold higher in the intervention group compared to controls, but these differences were not statistically significant. Tumor necrosis factor-α (TNF-α) mRNA levels were elevated after the intervention, but we did not detect significant changes in the downstream apoptosis markers caspase 8 and 3. Mitochondrial biogenesis markers (PGC1α and TFAm) were increased by the intervention, but this was not accompanied by significant changes in mitochondrial complex content and activity. In conclusion, although exploratory in nature, this study is among the first to report the stimulation of cellular quality control mechanisms elicited by a weight loss and exercise program in older obese women.
doi:10.1089/rej.2010.1132
PMCID: PMC3136739  PMID: 21631380
19.  Functional Pain Severity and Mobility in Overweight Older Men and Women with Chronic Low Back Pain: Part I 
Objective
This study determined whether mobility and functional pain were different among older men and women with chronic low back pain (LBP) and varying body mass index (BMI) levels.
Design
This was a comparative, descriptive study of obese, older adults with LBP (N=55; 60-85 years). Participants were stratified based on BMI: overweight (25-29.9 kg/m2), obese (30-34.9 kg/m2) and severely obese (35 kg/m2). Participants completed a functional test battery (walking endurance, chair rise, stair climb, 7-day activity monitoring, gait parameters) and pain ratings with activity (‘functional pain’).
Results
Functional pain scores during walking and stair climb were highest in the severely obese group compared with the overweight group (p<0.05), but functional test scores were not found to be significantly different by BMI. Gait base of support was 36% greater and single/double support times were 3.1-6.1% greater in the severely obese group compared to the overweight group (p<0.05). Women had slower chair rise and stair climb times, and had slower walking velocity than men. Daily step numbers were lowest in the severely obese group compared with the obese and overweight groups (2971 vs 3511 and 4421 steps/day; p<0.05), but were not different by gender. Normalized lumbar extensor, abdominal curl and leg press strength values were lowest in the severely obese group, and women had 18-34% lower strength values than men for all three exercises (p<0.05). Lumbar strength was associated with stair climb, chair rise and walking endurance times. BMI was an independent predictor of walking endurance time, but not steps taken per day.
Conclusions
In this study, obese persons reported higher functional pain values during walking and stair climb compared to overweight participants, and had lower lumbar strength. Rehabilitation strategies that include lumbar extensor strengthening may help improve functional mobility and walking duration, both of which can help with weight management in the obese, older adult with chronic LBP.
doi:10.1097/PHM.0b013e31828763a0
PMCID: PMC3676903  PMID: 23478453
Low Back Pain; Obesity; Walking; Physical Function; Body Mass Index
20.  Cost-Effectiveness of Interventions to Promote Physical Activity: A Modelling Study 
PLoS Medicine  2009;6(7):e1000110.
Linda Cobiac and colleagues model the costs and health outcomes associated with interventions to improve physical activity in the population, and identify specific interventions that are likely to be cost-saving.
Background
Physical inactivity is a key risk factor for chronic disease, but a growing number of people are not achieving the recommended levels of physical activity necessary for good health. Australians are no exception; despite Australia's image as a sporting nation, with success at the elite level, the majority of Australians do not get enough physical activity. There are many options for intervention, from individually tailored advice, such as counselling from a general practitioner, to population-wide approaches, such as mass media campaigns, but the most cost-effective mix of interventions is unknown. In this study we evaluate the cost-effectiveness of interventions to promote physical activity.
Methods and Findings
From evidence of intervention efficacy in the physical activity literature and evaluation of the health sector costs of intervention and disease treatment, we model the cost impacts and health outcomes of six physical activity interventions, over the lifetime of the Australian population. We then determine cost-effectiveness of each intervention against current practice for physical activity intervention in Australia and derive the optimal pathway for implementation. Based on current evidence of intervention effectiveness, the intervention programs that encourage use of pedometers (Dominant) and mass media-based community campaigns (Dominant) are the most cost-effective strategies to implement and are very likely to be cost-saving. The internet-based intervention program (AUS$3,000/DALY), the GP physical activity prescription program (AUS$12,000/DALY), and the program to encourage more active transport (AUS$20,000/DALY), although less likely to be cost-saving, have a high probability of being under a AUS$50,000 per DALY threshold. GP referral to an exercise physiologist (AUS$79,000/DALY) is the least cost-effective option if high time and travel costs for patients in screening and consulting an exercise physiologist are considered.
Conclusions
Intervention to promote physical activity is recommended as a public health measure. Despite substantial variability in the quantity and quality of evidence on intervention effectiveness, and uncertainty about the long-term sustainability of behavioural changes, it is highly likely that as a package, all six interventions could lead to substantial improvement in population health at a cost saving to the health sector.
Please see later in the article for Editors' Summary
Editors' Summary
Background
The human body needs regular physical activity throughout life to stay healthy. Physical activity—any bodily movement produced by skeletal muscles that uses energy—helps to maintain a healthy body weight and to prevent or delay heart disease, stroke, type 2 diabetes, colon cancer, and breast cancer. In addition, physically active people feel better and live longer than physically inactive people. For an adult, 30 minutes of moderate physical activity—walking briskly, gardening, swimming, or cycling—at least five times a week is sufficient to promote and maintain health. But at least 60% of the world's population does not do even this modest amount of physical activity. The daily lives of people in both developed and developing countries are becoming increasingly sedentary. People are sitting at desks all day instead of doing manual labor; they are driving to work in cars instead of walking or cycling; and they are participating less in physical activities during their leisure time.
Why Was This Study Done?
In many countries, the chronic diseases that are associated with physical inactivity are now a major public-health problem; globally, physical inactivity causes 1.9 million deaths per year. Clearly, something has to be done about this situation. Luckily, there is no shortage of interventions designed to promote physical activity, ranging from individual counseling from general practitioners to mass-media campaigns. But which intervention or package of interventions will produce the optimal population health benefits relative to cost? Although some studies have examined the cost-effectiveness of individual interventions, different settings for analysis and use of different methods and assumptions make it difficult to compare results and identify which intervention approaches should be give priority by policy makers. Furthermore, little is known about the cost-effectiveness of packages of interventions. In this study, the researchers investigate the cost-effectiveness in Australia (where physical inactivity contributes to 10% of deaths) of a package of interventions designed to promote physical activity in adults using a standardized approach (ACE-Prevention) to the assessment of the cost-effectiveness of health-care interventions.
What Did the Researchers Do and Find?
The researchers selected six interventions for their study: general practitioner “prescription” of physical activity; general practitioner referral to an exercise physiologist; a mass-media campaign to promote physical activity; the TravelSmart car use reduction program; a campaign to encourage the use of pedometers to increase physical activity; and an internet-based program. Using published data on the effects of physical activity on the amount of illness and death caused by breast and colon cancer, heart disease, stroke, and type 2 diabetes and on the effectiveness of each intervention, the researchers calculated the health outcomes of each intervention in disability-adjusted life years (DALY; a year of healthy life lost because of premature death or disability) averted over the lifetime of the Australian population. They also calculated the costs associated with each intervention offset by the costs associated with the five conditions listed above. These analyses showed that the pedometer program and the mass-media campaign were likely to be the most cost-effective interventions. These interventions were also most likely to be cost-saving. Referral to an exercise physiologist was the least cost-effective intervention. The other three interventions, though unlikely to be cost-saving, were likely to be cost-effective. Finally, a package of all six interventions would be cost-effective and would avert 61,000 DALYs, a third of what could be achieved if every Australian did 30 minutes of physical activity five times a week.
What Do These Findings Mean?
As in all modeling studies, these findings depend on the quality of the data and on the assumptions included by the researchers in their calculations. Unfortunately, there was substantial variability in the quantity and quality of evidence on the effectiveness of each intervention and uncertainty about the long-term effects of each intervention. Nevertheless, the findings presented in this study suggest that the assessment of the cost-effectiveness of a combination of interventions designed to promote physical activity might provide policy makers with some guidance about the best way to reduce the burden of disease caused by physical inactivity. More specifically, for Australia, these findings suggest that the package of the six interventions considered here is likely to provide a cost-effective way to substantially improve the health of the nation.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000110.
The World Health Organization provides information about physical activity and health (in several languages); it also provides an explanation of DALYs
The US Centers for Disease Control and Prevention provides information on physical activity for different age groups and for health professionals
The UK National Health Service information source Choices also explains the benefits of regular physical activity
MedlinePlus has links to other resources about exercise and physical fitness (in English and Spanish)
The University of Queensland Web site has more information on ACE-Prevention (Assessing Cost-Effectiveness Prevention)
doi:10.1371/journal.pmed.1000110
PMCID: PMC2700960  PMID: 19597537
21.  Bariatric Surgery 
Executive Summary
Objective
To conduct an evidence-based analysis of the effectiveness and cost-effectiveness of bariatric surgery.
Background
Obesity is defined as a body mass index (BMI) of at last 30 kg/m2.1 Morbid obesity is defined as a BMI of at least 40 kg/m2 or at least 35 kg/m2 with comorbid conditions. Comorbid conditions associated with obesity include diabetes, hypertension, dyslipidemias, obstructive sleep apnea, weight-related arthropathies, and stress urinary incontinence. It is also associated with depression, and cancers of the breast, uterus, prostate, and colon, and is an independent risk factor for cardiovascular disease.
Obesity is also associated with higher all-cause mortality at any age, even after adjusting for potential confounding factors like smoking. A person with a BMI of 30 kg/m2 has about a 50% higher risk of dying than does someone with a healthy BMI. The risk more than doubles at a BMI of 35 kg/m2. An expert estimated that about 160,000 people are morbidly obese in Ontario. In the United States, the prevalence of morbid obesity is 4.7% (1999–2000).
In Ontario, the 2004 Chief Medical Officer of Health Report said that in 2003, almost one-half of Ontario adults were overweight (BMI 25–29.9 kg/m2) or obese (BMI ≥ 30 kg/m2). About 57% of Ontario men and 42% of Ontario women were overweight or obese. The proportion of the population that was overweight or obese increased gradually from 44% in 1990 to 49% in 2000, and it appears to have stabilized at 49% in 2003. The report also noted that the tendency to be overweight and obese increases with age up to 64 years. BMI should be used cautiously for people aged 65 years and older, because the “normal” range may begin at slightly above 18.5 kg/m2 and extend into the “overweight” range.
The Chief Medical Officer of Health cautioned that these data may underestimate the true extent of the problem, because they were based on self reports, and people tend to over-report their height and under-report their weight. The actual number of Ontario adults who are overweight or obese may be higher.
Diet, exercise, and behavioural therapy are used to help people lose weight. The goals of behavioural therapy are to identify, monitor, and alter behaviour that does not help weight loss. Techniques include self-monitoring of eating habits and physical activity, stress management, stimulus control, problem solving, cognitive restructuring, contingency management, and identifying and using social support. Relapse, when people resume old, unhealthy behaviour and then regain the weight, can be problematic.
Drugs (including gastrointestinal lipase inhibitors, serotonin norepinephrine reuptake inhibitors, and appetite suppressants) may be used if behavioural interventions fail. However, estimates of efficacy may be confounded by high rates of noncompliance, in part owing to the side effects of the drugs. In addition, the drugs have not been approved for indefinite use, despite the chronic nature of obesity.
The Technology
Morbidly obese people may be eligible for bariatric surgery. Bariatric surgery for morbid obesity is considered an intervention of last resort for patients who have attempted first-line forms of medical management, such as diet, increased physical activity, behavioural modification, and drugs.
There are various bariatric surgical procedures and several different variations for each of these procedures. The surgical interventions can be divided into 2 general types: malabsorptive (bypassing parts of the gastrointestinal tract to limit the absorption of food), and restrictive (decreasing the size of the stomach so that the patient is satiated with less food). All of these may be performed as either open surgery or laparoscopically. An example of a malabsorptive technique is Roux-en-Y gastric bypass (RYGB). Examples of restrictive techniques are vertical banded gastroplasty (VBG) and adjustable gastric banding (AGB).
The Ontario Health Insurance Plan (OHIP) Schedule of Benefits for Physician Services includes fee code “S120 gastric bypass or partition, for morbid obesity” as an insured service. The term gastric bypass is a general term that encompasses a variety of surgical methods, all of which involve reconfiguring the digestive system. The term gastric bypass does not include AGB. The number of gastric bypass procedures funded and done in Ontario, and funded as actual out-of-country approvals,2 is shown below.
Number of Gastric Bypass Procedures by Fiscal Year: Ontario and Actual Out-of-Country (OOC) Approvals
Data from Provider Services, MOHLTC
Courtesy of Provider Services, Ministry of Health and Long Term Care
Review Strategy
The Medical Advisory Secretariat reviewed the literature to assess the effectiveness, safety, and cost-effectiveness of bariatric surgery to treat morbid obesity. It used its standard search strategy to retrieve international health technology assessments and English-language journal articles from selected databases. The interventions of interest were bariatric surgery and, for the controls, either optimal conventional management or another type of bariatric procedure. The outcomes of interest were improvement in comorbid conditions (e.g., diabetes, hypertension); short- and long-term weight loss; quality of life; adverse effects; and economic analysis data. The databases yielded 15 international health technology assessments or systematic reviews on bariatric surgery.
Subsequently, the Medical Advisory Secretariat searched MEDLINE and EMBASE from April 2004 to December 2004, after the search cut-off date of April, 2004, for the most recent systematic reviews on bariatric surgery. Ten studies met the inclusion criteria. One of those 10 was the Swedish Obese Subjects study, which started as a registry and intervention study, and then published findings on people who had been enrolled for at least 2 years or at least 10 years. In addition to the literature review of economic analysis data, the Medical Advisory Secretariat also did an Ontario-based economic analysis.
Summary of Findings
Bariatric surgery generally is effective for sustained weight loss of about 16% for people with BMIs of at least 40 kg/m2 or at least 35 kg/m2 with comorbid conditions (including diabetes, high lipid levels, and hypertension). It also is effective at resolving the associated comorbid conditions. This conclusion is largely based on level 3a evidence from the prospectively designed Swedish Obese Subjects study, which recently published 10-year outcomes for patients who had bariatric surgery compared with patients who received nonsurgical treatment. (1)
Regarding specific procedures, there is evidence that malabsorptive techniques are better than other banding techniques for weight loss and resolution of comorbid illnesses. However, there are no published prospective, long-term, direct comparisons of these techniques available.
Surgery for morbid obesity is considered an intervention of last resort for patients who have attempted first-line forms of medical management, such as diet, increased physical activity, behavioural modification, and drugs. In the absence of direct comparisons of active nonsurgical intervention via caloric restriction with bariatric techniques, the following observations are made:
A recent systematic review examining the efficacy of major commercial and organized self-help weight loss programs in the United States concluded that the evidence to support the use of such programs was suboptimal, except for one trial on Weight Watchers. Furthermore, the programs were associated with high costs, attrition rates, and probability of regaining at least 50% of the lost weight in 1 to 2 years. (2)
A recent randomized controlled trial reported 1-year outcomes comparing weight loss and metabolic changes in severely obese patients assigned to either a low-carbohydrate diet or a conventional weight loss diet. At 1 year, weight loss was similar for patients in each group (mean, 2–5 kg). There was a favourable effect on triglyceride levels and glycemic control in the low-carbohydrate diet group. (3)
A decision-analysis model showed bariatric surgery results in increased life expectancy in morbidly obese patients when compared to diet and exercise. (4)
A cost-effectiveness model showed bariatric surgery is cost-effective relative to nonsurgical management. (5)
Extrapolating from 2003 data from the United States, Ontario would likely need to do 3,500 bariatric surgeries per year. It currently does 508 per year, including out-of-country surgeries.
PMCID: PMC3382415  PMID: 23074460
22.  Effect of Home-Based Well-Rounded Exercise in Community-Dwelling Older Adults 
The purpose of this study was to assess the efficacy of a home-based well-rounded exercise program (WREP) in older adults. Forty sedentary community-dwelling older adults were randomly assigned to an exercise group (n = 23; aged 62-80 yr, average: 69.2 ± 5.2; 12 men and 11 women) or a control group (n = 17; aged 63-85 yr, average: 70.1 ± 6.6; 5 men and 12 women). The exercise group performed a 12-wk WREP which included aerobic exercise (walking) on about 3 days·wk-1 for 37 min·day-1; elastic band-based resistance exercises for the major muscle groups on about 3 days·wk-1 for 26 min; and flexibility exercises (stretching) on about 4 days·wk-1 for 19 min·day-1. General physical characteristics, functional strength (Arm Curl [AC], Chair Stand [CS]), dynamic balance and agility (Up & Go [UG]), flexibility (Back Scratch [BS], Sit & Reach [SR]), and endurance (12-min walk [12-MW]) were measured. Following the 12-wk home-based WREP, improvements were observed in AC, CS, UG, BS, SR and 12-MW for the exercise group but not for the control group. These results suggest that the home-based WREP can improve overall fitness in older adults.
Key PointsWalking, elastic band exercise and stretching were prescribed as a Well-Rounded Exercise Program for older adults.By combining aerobic, resistance and flexibility exercises, a Well-Rounded Exercise Program was effective for improving endurance, functional strength, dynamic balance and agility, and flexibility.Community-based exercise classes motivated older adults to perform home-based exercises.
PMCID: PMC3899673  PMID: 24501569
Physical fitness; aerobic exercise; resistance exercise; flexibility exercise; adherence
23.  The effect of walking on falls in older people: the 'Easy Steps to Health' randomized controlled trial study protocol 
BMC Public Health  2011;11:888.
Background
Falls in older people continue to be a major public health issue in industrialized countries. Extensive research into falls prevention has identified exercise as a proven fall prevention strategy. However, despite over a decade of promoting physical activity, hospitalisation rates due to falls injuries in older people are still increasing. This could be because efforts to increase physical activity amongst older people have been unsuccessful, or the physical activity that older people engage in is insufficient and/or inappropriate. The majority of older people choose walking as their predominant form of exercise. While walking has been shown to lower the risk of many chronic diseases its role in falls prevention remains unclear. This paper outlines the methodology of a study whose aims are to determine: if a home-based walking intervention will reduce the falls rate among healthy but inactive community-dwelling older adults (65 + years) compared to no intervention (usual activity) and; whether such an intervention can improve risk factors for falls, such as balance, strength and reaction time.
Methods/Design
This study uses a randomised controlled trial design.
A total of 484 older people exercising less than 120 minutes per week will be recruited through the community and health care referrals throughout Sydney and neighboring regions. All participants are randomised into either the self-managed walking program group or the health-education waiting list group using a block randomization scheme.
Outcome measures include prospective falls and falls injuries, quality of life, and physical activity levels. A subset of participants (n = 194) will also receive physical performance assessments comprising of tests of dynamic balance, strength, reaction time and lower limb functional status.
Discussion
Certain types of physical activity can reduce the risk of falls. As walking is already the most popular physical activity amongst older people, if walking is shown to reduce falls the public health implications could be enormous. Conversely, if walking does not reduce falls in older people, or even puts older people at greater risk, then health resources targeting falls prevention need to be invested elsewhere.
Trial Registration
Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000380099
doi:10.1186/1471-2458-11-888
PMCID: PMC3251253  PMID: 22115340
24.  The SHED-IT community trial study protocol: a randomised controlled trial of weight loss programs for overweight and obese men 
BMC Public Health  2010;10:701.
Background
Obesity is a major cause of preventable death in Australia with prevalence increasing at an alarming rate. Of particular concern is that approximately 68% of men are overweight/obese, yet are notoriously difficult to engage in weight loss programs, despite being more susceptible than women to adverse weight-related outcomes. There is a need to develop and evaluate obesity treatment programs that target and appeal to men. The primary aim of this study is to evaluate the efficacy of two relatively low intensity weight loss programs developed specifically for men.
Methods and Design
The study design is an assessor blinded, parallel-group randomised controlled trial that recruited 159 overweight and obese men in Newcastle, Australia. Inclusion criteria included: BMI 25-40 (kg/m2); no participation in other weight loss programs during the study; pass a health-screening questionnaire and pre-exercise risk assessment; available for assessment sessions; access to a computer with e-mail and Internet facilities; and own a mobile phone. Men were recruited to the SHED-IT (Self-Help, Exercise and Diet using Internet Technology) study via the media and emails sent to male dominated workplaces. Men were stratified by BMI category (overweight, obese class I, obese class II) and randomised to one of three groups: (1) SHED-IT Resources - provision of materials (DVD, handbooks, pedometer, tape measure) with embedded behaviour change strategies to support weight loss; (2) SHED-IT Online - same materials as SHED-IT Resources plus access to and instruction on how to use the study website; (3) Wait-list Control. The intervention programs are three months long with outcome measures taken by assessors blinded to group allocation at baseline, and 3- and 6-months post baseline. Outcome measures include: weight (primary outcome), % body fat, waist circumference, blood pressure, resting heart rate, objectively measured physical activity, self-reported dietary intake, sedentary behaviour, physical activity and dietary cognitions, sleepiness, quality of life, and perceived sexual health. Generalised linear mixed models will be used to assess all outcomes for the impact of group (Resources, Online, and Control), time (treated as categorical with levels baseline, 3-months and 6-months) and the group-by-time interaction. These three terms will form the base model. 'Intention-to-treat' analysis will include all randomised participants.
Discussion
Our study will compare evidence-based and theoretically driven, low cost and easily disseminated strategies specifically targeting weight loss in men. The SHED-IT community trial will provide evidence to inform development and dissemination of sustainable strategies to reduce obesity in men.
Trial Registration
Australian New Zealand Clinical Trials Registry (ACTRN12610000699066)
doi:10.1186/1471-2458-10-701
PMCID: PMC2995796  PMID: 21078200
25.  Effect of intra-dialytic, low-intensity strength training on functional capacity in adult haemodialysis patients: a randomized pilot trial 
Nephrology Dialysis Transplantation  2010;25(6):1936-1943.
Background. Kidney failure is associated with muscle wasting and physical impairment. Moderate- to high-intensity strength training improves physical performance, nutritional status and quality of life in people with chronic kidney disease and in dialysis patients. However, the effect of low-intensity strength training has not been well documented, thus representing the objective of this pilot study.
Methods. Fifty participants (mean ± SD, age 69 ± 13 years) receiving long-term haemodialysis (3.7 ± 4.2 years) were randomized to intra-dialytic low-intensity strength training or stretching (attention-control) exercises twice weekly for a total of 48 exercise sessions. The primary study outcome was physical performance assessed by the Short Physical Performance Battery score (SPPB) after 36 sessions, if available, or carried forward from 24 sessions. Secondary outcomes included lower body strength, body composition and quality of life. Measurements were obtained at baseline and at completion of 24 (mid), 36 (post) and 48 (final) exercise sessions.
Results. Baseline median (IQR) SPPB score was 6.0 (5.0), with 57% of the participants having SPPB scores below 7. Exercise adherence was 89 ± 15%. The primary outcome could be computed in 44 participants. SPPB improved in the strength training group compared to the attention-control group [21.1% (43.1%) vs. 0.2% (38.4%), respectively, P = 0.03]. Similarly, strength training participants exhibited significant improvements from baseline compared to the control group in knee extensor strength, leisure-time physical activity and self-reported physical function and activities of daily living (ADL) disability; all P < 0.02. Adverse events were common but not related to study participation.
Conclusions. Intra-dialytic, low-intensity progressive strength training was safe and effective among maintenance dialysis patients. Further studies are needed to establish the generalizability of this strength training program in dialysis patients.
doi:10.1093/ndt/gfp739
PMCID: PMC2902890  PMID: 20100734
haemodialysis; older adults; physical performance; Short Physical Performance Battery; strength training

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