Coronary heart disease (CHD) remains a leading cause of death in the United States. The Framingham Risk Score (FRS) was developed to help clinicians in determining their patients’ CHD risk. We hypothesize that the FRS will be significantly predictive of CHD events among men in the Aerobics Center Longitudinal Study (ACLS) population.
Our study consisted of 34,557 men who attended the Cooper Clinic in Dallas, Texas, for a baseline clinical examination from 1972 through 2002. CHD events included self-reported myocardial infarction or revascularization or death due to CHD. During the 12-year follow-up 587 CHD events occurred. Multivariable-adjusted hazard ratios generated from ACLS analysis were compared with the application of FRS to the Framingham Heart Study (FHS).
The ACLS cohort produced similar hazard ratios to the FHS. The adjusted Cox proportional hazard model revealed that men with total cholesterol of 280 mg/dL or greater were 2.21 (95% confidence interval (CI), 1.59–3.09) times more likely to have a CHD event than men with total cholesterol from 160 through 199mg/dL; men with diabetes were 1.63 (95% CI, 1.35–1.98) times more likely to experience a CHD event than men without diabetes.
The FRS significantly predicts CHD events in the ACLS cohort. To the best of our knowledge, this is the first report of a large, single-center cohort study to validate the FRS by using extensive laboratory and clinical measurements.
Low cardiorespiratory fitness (CRF) is a well-established risk factor for all-cause and cardiovascular disease mortality. African Americans have higher rates of cardiovascular disease compared to their Caucasian counterparts. However, the extent to which lower CRF levels contribute to the excess risk in African Americans has not been fully explored. The purpose of this review is to: 1) explore the literature evaluating the relationship between CRF and mortality specifically in African American populations; and 2) critically evaluate the studies which have compared CRF between African American and Caucasians in epidemiological studies and clinical trials. We have further discussed several potential mechanisms that may contribute to the observation of lower CRF levels in African American compared to Caucasian adults including potential racial differences in physical activity levels, muscle fiber type distribution, and hemoglobin levels. If lower CRF is generally present in African Americans compared to Caucasians, and is of a clinically meaningful difference, this may represent an important public health concern.
To study the protective role of lower resting heart rate (RHR) on cardiovascular disease (CVD) and all-cause mortality.
Patients and Methods
Participants (n=51,936) who received a baseline medical examination between January 1, 1974 and December 31, 2002 were recruited from the Cooper Clinic, Dallas, Texas. They completed a medical questionnaire and underwent clinical evaluation. Participants with CVD or cancer, those who did not achieve at least 85% of their age-predicted maximal heart rate or who had <1 year of mortality follow-up were excluded from the study. SAS was used for statistical analysis. Relative risks and 95% confidence intervals of all-cause and CVD mortality across RHR categories were estimated using Cox proportional hazard models.
Highest cardiorespiratory fitness (CRF) with lower mortality was found in individuals with a RHR <60 bpm. Similarly, participants with a higher RHR, >80 bpm, were at greater risk for both CVD and all-cause mortality when compared with RHR <60 bpm. This analysis was followed by the stratification of the data by hypertension, where hypertensive individuals with high RHRs (≥80 bpm) were found at greater risk for CVD and all-cause mortality when compared to those with hypertension and lower RHRs (<60 bpm). Additionally unfit individuals with high RHR had the greatest risk for CVD and all-cause mortality. Interestingly, the unfit with low RHR group had a similar risk for both CVD and all-cause mortality as the fit with high RHR group.
Lower levels of CRF and higher RHR are linked with greater CVD and all-cause mortality1.
To examine associations among age, physical activity (PA), and birth cohort on body mass index (BMI) percentiles in men.
Design and Methods
Longitudinal analyses using quantile regression were conducted among men with ≥ two examinations between 1970 and 2006 from the Aerobics Center Longitudinal Study (n=17,759). Height and weight were measured; men reported their PA and were categorized as inactive, moderately or highly active at each visit. Analyses allowed for longitudinal changes in PA.
BMI was greater in older than younger men and in those born in 1960 than those born in 1940. Inactive men gained weight significantly more rapidly than active men. At the 10th percentile, increases in BMI among inactive, moderately active, and highly active men were 0.092, 0.078, and 0.069 kg/m2 per year of age, respectively. The 10th percentile increased by 0.081 kg/m2 per birth year and by 0.180 kg/m2 at the 90th percentile, controlling for age.
Although BMI increased with age, PA reduced the magnitude of the gradient among active compared to inactive men. Regular PA had an important, protective effect against weight gain. This study provides evidence of the utility of quantile regression to examine the specific causes of the obesity epidemic.
obesity; physical activity; quantile regression; longitudinal; men
Novel approaches to the treatment of stimulant abuse and dependence are needed. Clinical data examining the use of exercise as a treatment for the abuse of nicotine, alcohol, and other substances suggest that exercise may be a beneficial treatment for stimulant abuse. In addition, exercise has been associated with improvements in many other health-related areas that may be adversely affected by stimulant use or its treatment, such as sleep disturbance, cognitive function, mood, weight, quality of life, and anhedonia. Neurobiological evidence provides plausible mechanisms by which exercise could positively affect treatment outcomes in stimulant abuse. The National Institute on Drug Abuse (NIDA) Clinical Trials Network (CTN) CTN-0037 Stimulant Reduction Intervention using Dosed Exercise (STRIDE) study is a multisite randomized clinical trial that compares exercise to health education as potential treatments for stimulant abuse or dependence. If effective, exercise may provide an additional approach to the treatment of stimulant use disorders.
stimulant abuse; stimulant dependence; exercise; health education; behavioral intervention
Physical inactivity remains an under-researched field in terms of studying burden of disease at provincial level, and no studies have examined the effects of inactivity on life expectancy (LE) in China. The purpose of this study was to estimate mortality risk and LE effects associated with insufficient levels of physical activity in Jiangxi province.
Prevalence of risk factors and mortality counts were extracted from Chronic Diseases and Risk Factors Surveillance Survey (CDRFSS) and Disease Surveillance Points system (DSP), respectively. Insufficient physical activity (IPA) was defined as less than 150 minutes of moderate-intensity physical activity or 60 minutes of vigorous-intensity physical activity per week, accumulated across work, home, transport and discretionary domains. Population-attributable fractions (PAF) were used to calculate the mortality attributable to risk factors, and life table methods were used to estimate the LE gains and LE shifts. Monte Carlo simulation techniques were used for uncertainty analysis. Overall, 5 885 (95% uncertainly interval (UI), 5 047–6 506) and 8 578 (95% UI, 8 227–9 789) deaths in Jiangxi province were attributable to IPA in 2007 and 2010, respectively. The LE gains for elimination of attributable deaths were 0.68 (95% UI, 0.61–076) in 2007, and increased to 0.91 (95% UI, 0.81–1.10) in 2010. If the prevalence of IPA in 2010 had been decreased by 50% or 30%, 3 678 (95% UI, 3 220–4 229) or 2 090 (95% UI, 1 771–2 533) deaths would be avoided, and 0.40 (95% UI, 0.34–0.53) or 0.23 (95% UI, 0.16–0.31) years of LE gained, respectively.
Adults in Jiangxi province of China have a high and increasing prevalence of IPA. Due to the deaths and potential LE gains associated with IPA, there is an urgent need to promote physical activity, one of the most modifiable risk factors, within China's health care reform agenda.
Little is known if the levels of physical activity required for the prevention of incident heart failure (HF) and other cardiovascular events vary in community-dwelling older adults.
We studied 5503 Cardiovascular Health Study (CHS) participants, age ≥65 years, free of baseline HF. Weekly metabolic equivalent task-minutes (MET-minutes), estimated using baseline total leisure-time energy expenditure, were used to categorize participants into four physical activity groups: inactive (0 MET-minutes; n=489; reference), low (1–499; n=1458), medium (500–999; n=1086) and high (≥1000; n=2470).
Participants had a mean (±SD) age of 73 (±6) years, 58% were women, and 15% African American. During 13 years of follow-up, centrally-adjudicated incident HF occurred in 26%, 23%, 20%, and 19% of participants with no, low, medium and high physical activity, respectively (trend p <0.001). Compared with inactive older adults, age-sex-race-adjusted hazard ratios (95% confidence intervals) for incident HF associated with low, medium and high physical activity were 0.87 (0.71–1.06; p=0.170), 0.68 (0.54–0.85; p=0.001) and 0.60 (0.49–0.74; p<0.001), respectively (trend p <0.001). Only high physical activity had significant independent association with lower risk of incident HF (HR, 0.79; 95% CI, 0.64–0.97; p=0.026). All levels of physical activity had significant independent association with lower risk of incident acute myocardial infarction (AMI), stroke and cardiovascular mortality.
In community-dwelling older adults, high level of physical activity was associated with lower risk of incident HF, but all levels of physical activity were associated with lower risk of incident AMI, stroke, and cardiovascular mortality.
Physical activity; MET-minutes; Incident heart failure; Older adults
Chronic Inflammation is linked to poor lifestyle behaviors and a variety of chronic diseases that are prevalent among African Americans, especially in the southeastern U.S.
The goal of the study was to test the effect of a community-based diet, physical activity, and stress reduction intervention conducted in 2009–2012 on reducing serum C-reactive protein (CRP) in overweight and obese African-American adults.
An RCT intervention was designed jointly by members of African-American churches and academic researchers. In late 2012, regression (i.e., mixed) models were fit that included both intention-to-treat and post hoc analyses conducted to identify important predictors of intervention success. Outcomes were assessed at 3 months and 1 year.
At baseline, the 159 individuals who were recruited in 13 churches and had evaluable outcome data were, on average, obese (BMI=33.1 [±7.1]) and had a mean CRP level of 3.7 (±3.9) mg/L. Reductions were observed in waist-to-hip ratio at 3 months (2%, p=0.03) and 1 year (5%, p<0.01). In female participants attending ≥60% of intervention classes, there was a significant decrease in CRP at 3 months of 0.8 mg/L (p=0.05), but no change after 1 year. No differences were noted in BMI or interleukin-6.
In overweight/obese, but otherwise “healthy,” African-American church members with very high baseline CRP levels, this intervention produced significant reductions in CRP at 3 and 12 months, and in waist-to-hip ratio, which is an important anthropometric predictor of overall risk of inflammation and downstream health effects.
This study is registered at www.clinicaltrials.gov NCT01760902.
To evaluate the association between coffee consumption and mortality from all causes and cardiovascular disease (CVD).
Patients and Methods
Data from the Aerobics Center Longitudinal Study (ACLS) representing a total of 43,727 participants contributing to 699,632 person-years of follow-up time, were included. Baseline data were collected by an in-person interview based on standardized questionnaires and a medical examination, including fasting blood chemistry analysis, anthropometry, blood pressure, electrocardiography, and a maximal graded exercise test, between February 3, 1971 and December 30, 2002. Cox regression analysis was used to quantify the association between coffee consumption and all-cause and cause-specific mortality.
During the 17-year median follow-up period, 2512 deaths occurred (32% due to CVD). In multivariate analyses, coffee intake was positively associated with all-cause mortality in men. Men who drank >28 cups coffee per week had higher all-cause mortality (hazard ratio (HR): 1.21; 95% confidence interval (CI): 1.04–1.40). However, after stratification based on age, both younger (<55 years) men and women showed a statistically significant association between high coffee consumption (>28 cups/week) and all-cause mortality, after adjusting for potential confounders and fitness level (HR: 1.56; 95% CI: 1.30–1.87 for men and HR: 2.13; 95% CI: 1.26–3.59 for women, respectively).
In this large cohort, a positive association between coffee consumption and all-cause mortality was observed among men and both men and women <55 years of age. Based on our findings, it seems appropriate to suggest that younger people avoid heavy coffee consumption (ie, averaging >4 cups/day). However, this finding should be assessed in future studies from other populations.
Low cardiorespiratory fitness (CRF) is an independent risk factor for cardiovascular disease (CVD), especially in individuals with type 2 diabetes. Age-predicted, sex-stratified, and maximal MET cut points have been developed to determine the risk of CVD events and mortality in low CRF categories. We examined the proportion of Health Benefits of Aerobic and Resistance Training in Individuals With Type 2 Diabetes (HART-D) participants above these cut points before and after 9 months of aerobic training (AT), resistance training (RT), or a combination of both (ATRT).
RESEARCH DESIGN AND METHODS
Participants from the HART-D study (n = 196) who were randomly assigned to exercise training (AT, RT, or ATRT) or to a nonexercise control group between April 2007 and August 2009 were used in this ancillary study. Cut points were previously established for age-predicted METs (>100% and >85%, mean and increased CVD risk, respectively), age- and sex-stratified METs (Aerobic Center Longitudinal Study), and clinically discernible METs (men >8.0, women >6.5).
Baseline prevalence of participants above these cut points was similar for all intervention groups (P > 0.50) and ranged from 11.9% (>100% age predicted) to 55.1% (>85% age predicted). Baseline prevalence and age-, sex-, and race/ethnic group–adjusted percentage of participants above each cut point increased significantly after AT and ATRT (P < 0.05 for all).
Structured exercise training, especially the AT component, was associated with a greater number of participants moving above established cut points indicative of low CRF. These results have public health and clinical implications for the growing number of patients with type 2 diabetes at high risk for CVD.
The aim of this study is to investigate the independent and joint effects of cardiorespiratory fitness (CRF) and body mass index (BMI) on cancer mortality in a low body mass index population.
We evaluated CRF and BMI in relation to cancer mortality in 8760 Japanese men. The median BMI was 22.6 kg/m2 (IQR: 21.0-24.3). The mean follow-up period was more than 20 years. Hazard ratios and 95% CI were obtained using a Cox proportional hazards model while adjusting for several confounding factors.
Using the 2nd tertile of BMI (21.6-23.6 kg/m2) as reference, hazard ratios and 95% CI for the lowest tertile of BMI (18.5-21.5) were 1.26 (0.87–1.81), and 0.92 (0.64–1.34) for the highest tertile (23.7-37.4). Using the lowest tertile of CRF as reference, hazard ratios and 95% CIs for 2nd and highest tertiles of CRF were 0.78 (0.55–1.10) and 0.59 (0.40–0.88). We further calculated hazard ratios according to groups of men cross-tabulated by tertiles of CRF and BMI. Among men in the second tertile of BMI, those belonging to the lowest CRF tertile had a 53% lower risk of cancer mortality compared to those in the lowest CRF tertile (hazard ratio: 0.47, 95% CI: 0.23-0.97). Among those in the highest BMI tertile, the corresponding hazard ratio was 0.54 (0.25-1.17).
These results suggest that high CRF is associated with lower cancer mortality in a Japanese population of men with low average BMI.
Epidemiology; Maximal oxygen uptake; Physical activity; Exercise; Smoking
To investigate the associations between changes in body composition and fitness after exercise training and changes in hemoglobin A1c (HbA1c) in individuals with type 2 diabetes.
RESEARCH DESIGN AND METHODS
Participants (n = 201) were randomized to aerobic, resistance, or combined training for 9 months. HbA1c, waist circumference, total and trunk fat mass, appendicular fat mass, lean body mass, isokinetic leg muscle strength, peak O2 uptake, and estimated METs were assessed at baseline and follow-up. Change in HbA1c was evaluated across quartiles of change in body composition and fitness.
Change in HbA1c was associated with changes in body weight (r = 0.13, P = 0.052), waist circumference (r = 0.17, P = 0.013), trunk fat mass (r = 0.19, P = 0.005), and estimated METs (r = −0.16, P = 0.023). There was a trend in change in HbA1c across quartiles of waist circumference (P = 0.011), trunk fat mass (P = 0.020), and estimated METs (P = 0.011). Participants with increased estimated METs and reduced trunk fat mass had greater odds of having reduced HbA1c after training (3.48, 1.46–8.31). Finally, participants with increased estimated METs and reduced waist circumference were 2.81 (1.13–6.98) times more likely to have reduced HbA1c and type 2 diabetes medication use than those without improved fitness and central adiposity.
In patients with type 2 diabetes, a reduction in central adiposity and increase in fitness were the most prominent predictors of the change in HbA1c in response to exercise training.
Obstructive sleep apnea (OSA) predisposes individuals to cardiovascular morbidity, and cardiopulmonary exercise test (CPET) markers prognostic for cardiovascular disease have been found to be abnormal in adults with OSA. Due to the persistence of OSA and its cardiovascular consequences, whether the cardiovascular adaptations normally conferred by exercise are blunted in adults not utilizing established OSA treatment is unknown. The aims of this study were to document whether OSA participants have abnormal CPET responses and determine whether exercise modifies these CPET markers in individuals with OSA.
The CPET responses of 43 sedentary, overweight adults (body mass index [BMI]>25) with untreated OSA (apnea-hypopnea index [AHI]≥15) were compared against matched non-OSA controls (n=9). OSA participants were then randomized to a 12-week exercise training (n=27) or stretching control treatment (n=16), followed by a post-intervention CPET. Measures of resting, exercise, and post-exercise recovery heart rate (HRR), blood pressure, and ventilation, as well as peak oxygen consumption (VO2peak), were obtained.
OSA participants had blunted HRR compared to non-OSA controls at 1 (P=.03), 3 (P=.02), and 5 min post-exercise (P=.03). For OSA participants, exercise training improved VO2peak (P=.04) and HRR at 1 (P=.03), 3 (P<.01), and 5 min post-exercise (P<.001) compared to control. AHI change was associated with change in HRR at 5-min post-exercise (r=−.30, P<.05), but no other CPET markers.
These results suggest that individuals with OSA have autonomic dysfunction, and that exercise training, by increasing HRR and VO2peak, may attenuate autonomic imbalance and improve functional capacity independent of OSA severity reduction.
obstructive sleep apnea; exercise testing; exercise training; heart rate recovery; peak oxygen consumption
To measure the levels and patterns of physical activity, using accelerometers, of 11‐year‐old children participating in the Avon Longitudinal Study of Parents and Children (ALSPAC).
ALSPAC is a birth cohort study located in the former county of Avon, in the southwest of England. This study used data collected when the children were 11 years old.
5595 children (2662 boys, 2933 girls). The children are the offspring of women recruited to a birth cohort study during 1991–2. The median age (95% CI) of the children is now 11.8 (11.6 to 11.9) years.
Physical activity was measured over a maximum of 7 consecutive days using the MTI Actigraph accelerometer.
Main outcome measures
Level and pattern of physical activity.
The median physical activity level was 580 counts/min. Boys were more active than girls (median (IQR) 644 (528–772) counts/min vs 529 (444–638) counts/min, respectively). Only 2.5% (95% CI 2.1% to 2.9%) of children (boys 5.1% (95% CI 4.3% to 6.0%), girls 0.4% (95% CI 0.2% to 0.7%) met current internationally recognised recommendations for physical activity. Children were most active in summer and least active in winter (difference = 108 counts/min). Both the mother and partner's education level were inversely associated with activity level (p for trend <0.001 (both mother and partner)). The association was lost for mother's education (p for trend = 0.07) and attenuated for partner's education (p for trend = 0.02), after adjustment for age, sex, season, maternal age and social class.
A large majority of children are insufficiently active, according to current recommended levels for health.
To investigate changes in body composition after 12 months of high-intensity progressive resistance training (PRT) in relation to changes in insulin resistance (IR) or glucose homeostasis in older adults with type 2 diabetes.
RESEARCH DESIGN AND METHODS
One-hundred three participants were randomized to receive either PRT or sham exercise 3 days per week for 12 months. Homeostasis model assessment 2 of insulin resistance (HOMA2-IR) and glycosylated hemoglobin (HbA1c) were used as indices of IR and glucose homeostasis. Skeletal muscle mass (SkMM) and total fat mass were assessed using bioelectrical impedance. Visceral adipose tissue, mid-thigh cross-sectional area, and mid-thigh muscle attenuation were quantified using computed tomography.
Within the PRT group, changes in HOMA2-IR were associated with changes in SkMM (r = −0.38; P = 0.04) and fat mass (r = 0.42; P = 0.02). Changes in visceral adipose tissue tended to be related to changes in HOMA2-IR (r = 0.35; P = 0.07). Changes in HbA1c were related to changes in mid-thigh muscle attenuation (r = 0.52; P = 0.001). None of these relationships were present in the sham group (P > 0.05). Using ANCOVA models, participants in the PRT group who had increased SkMM had decreased HOMA2-IR (P = 0.05) and HbA1c (P = 0.09) compared with those in the PRT group who lost SkMM. Increases in SkMM in the PRT group decreased HOMA2-IR (P = 0.07) and HbA1c (P < 0.05) compared with those who had increased SkMM in the sham group.
Improvements in metabolic health in older adults with type 2 diabetes were mediated through improvements in body composition only if they were achieved through high-intensity PRT.
Treatment of COPD requires multiple pharmacological and non-pharmacological intervention strategies. One target is physical inactivity because it leads to disability and contributes to poor physical and mental health. Unfortunately, less than one percent of eligible patients have access to gold-standard pulmonary rehabilitation.
A single-site parallel group randomized trial was designed to determine if a self-management lifestyle physical activity intervention would improve physical functioning and dyspnea. During the first six weeks after enrollment patients receive COPD self-management education delivered by a health coach using a workbook and weekly telephone calls. Patients are then randomized to usual care or the physical activity intervention. The 20 week physical activity intervention is delivered by the health coach using a workbook supported by alternating one-on-one telephone counseling and computer assisted telephone calls. Theoretical foundations include social cognitive theory and the transtheoretical model.
Primary outcomes include change in Chronic Respiratory Questionnaire (CRQ) dyspnea domain and 6-minute walk distance measured at 6-, 12-, and 18-months after randomization. Secondary outcomes include other CRQ domains (fatigue, emotion, and mastery), SF-12, and health care utilization. Other measures include process outcomes and clinical characteristics.
This theory driven self-management lifestyle physical activity intervention is designed to reach patients unable to complete center-based pulmonary rehabilitation. Results will advance knowledge and methods for dissemination of a potentially cost-effective program for patients with COPD.
chronic obstructive pulmonary disease; self-management; physical activity; lifestyle; pulmonary rehabilitation; randomized trial
No studies have addressed the “fit but fat” paradigm using accelerometry data.
The study was to determine if 1) higher levels of accelerometer-determined physical activity are favorably associated with biomarkers in overweight or obese persons (objective 1); and 2) overweight or obese individuals who are sufficiently active have better or similar biomarker levels than normal weight persons who are not sufficiently active (objective 2).
Materials and Methods:
Data from the 2003-2006 National Health and Nutrition Examination Survey were analyzed and included 5,146 participants aged 20-85 years.
Regarding objective 1, obese active individuals had more favorable waist circumference, C-reactive protein, white blood cells, and neutrophil levels when compared to obese inactive individuals; similar results were found for overweight adults. Regarding objective 2, there were no significant differences between normal weight inactive individuals and overweight active individuals for nearly all biomarkers. Similarly, there were no significant differences between normal weight inactive individuals and obese active individuals for white blood cells, neutrophils, low-density lipoprotein cholesterol, total cholesterol, triglycerides, glucose, or homocysteine.
Physical activity has a protective effect on biomarkers in normal, overweight, and obese individuals, and overweight (not obese) active individuals have a similar cardiovascular profile than normal weight inactive individuals.
Accelerometry; Biomarkers; Fit but fat; Obesity
As an ancillary report to a large National Institutes of Health (NIH)–funded trial, we examined the effects of 6 months of exercise training at 50%, 100%, and 150% of the NIH Consensus Recommendations for physical activity (i.e., 4, 8, and 12 kcal/kg of energy expenditure/wk [KKW]) versus a nonexercise control group on the metabolic syndrome (MS) in sedentary, overweight, moderately hypertensive, postmenopausal women. We examined the clinically defined National Cholesterol Education Program MS, individual components scores, and summed z-scores, expressed as a continuous variable (zMS), using chi-square and general linear models to assess the clinical and progressive nature of MS, respectively. Our results showed significant improvements in zMS for all exercise groups and MS for the 8- and 12 KKW groups only (all, p for trend = 0.02). Post hoc analyses showed that 12 KKW for zMS and 8 and 12 KKW for MS was significant versus the control group (all, p <0.05). When examining the composite scores, we observed significant trends for improvement in waist circumference (p for trend = 0.001), fasting glucose (p for trend = 0.01), and systolic blood pressure (p for trend = 0.02), which appeared to be dose dependent, given the additive nature for incorporating the within-group improvements in waist circumference (4, 8, and 12 KKW), fasting glucose (8 and 12 KKW), and systolic blood pressure (12 KKW). Our results suggest that low-to-moderate intensity cardiorespiratory exercise appears to improve components of the MS in postmenopausal women at levels at or greater than NIH recommendations and that zMS improves at half the NIH recommendations. Greater levels of energy expenditure appear to enhance this effect by incorporating a greater number of requisite MS composite scores.
Reductions in skeletal muscle mass and increased adiposity are key elements in the aging process and in the pathophysiology of several chronic diseases. Systemic low grade inflammation associated with obesity has been shown to accelerate the age-related decline in skeletal muscle. The aim of this investigation was to determine the effects of 12 months of progressive resistance training (PRT) on systemic inflammation, and whether reductions in systemic inflammation were associated with changes in body composition. We hypothesized that reductions in systemic inflammation following 12 months of PRT in older adults with type 2 diabetes would be associated with reductions in adiposity and increases in skeletal muscle mass.
Participants (n = 103) were randomized to receive either PRT or sham-exercise, 3 days a week for 12 months. C-reactive protein (CRP) was used to assess systemic inflammation. Skeletal muscle mass and total fat mass were determined using bioelectrical impedance.
Twelve months of PRT tended to reduce CRP compared to sham exercise (β = −0.25, p = 0.087). Using linear mixed-effects models, the hypothesized relationships between body composition adaptations and CRP changes were significantly stronger for skeletal muscle mass (p = 0.04) and tended to be stronger for total fat mass (p = 0.07) following PRT when compared to sham-exercise. Using univariate regression models, stratified by group allocation, reductions in CRP were associated with increases in skeletal muscle mass (p = 0.01) and reductions in total fat mass (p = 0.02) in the PRT group, but not in the sham-exercise group (p = 0.87 and p = 0.32, respectively).
We have shown for the first time that reductions in systemic inflammation in older adults with type 2 diabetes following PRT were associated with increases in skeletal muscle mass. Furthermore, reductions in CRP were associated with reductions in adiposity, but only when associated with PRT. Lifestyle interventions aimed at reducing systemic inflammation in older adults with type 2 diabetes should therefore incorporate anabolic exercise such as PRT to optimize the anti-inflammatory benefits of favorable body composition adaptations.
PRT; Inflammation; Body composition; Skeletal muscle; Adiposity
Rising and epidemic rates of obesity in many parts of the world are leading to increased suffering and economic stress from diverting health care resources to treating a variety of serious, but preventable, chronic diseases etiologically linked to obesity, particularly type 2 diabetes mellitus and cardiovascular diseases. Despite decades of research into the causes of the obesity pandemic, we seem to be no nearer to a solution now than when the rise in body weights was first chronicled decades ago. The case is made that impediments to a clear understanding of the nature of the problem occur at many levels. These obstacles begin with defining obesity and include lax application of scientific standards of review, tenuous assumption making, flawed measurement and other methods, constrained discourse limiting examination of alternative explanations of cause, and policies that determine funding priorities. These issues constrain creativity and stifle expansive thinking that could otherwise advance the field in preventing and treating obesity and its complications. Suggestions are made to create a climate of open exchange of ideas and redirection of policies that can remove the barriers that prevent us from making material progress in solving a pressing major public health problem of the early 21st century.
Non-alcoholic fatty liver disease (NAFLD) is considered the liver component of the metabolic syndrome and is strongly associated with cardiometabolic diseases. In adults, cardiorespiratory fitness (CRF) is inversely associated with alanine aminotransferase (ALT), a blood biomarker for NAFLD. However, information regarding these associations is scarce for youth.
To examine associations between CRF, waist circumference (WC) and ALT in youth.
Data were obtained from youth (n=2844, 12-19 years) in the National Health and Nutrition Examination Survey (NHANES) 2001-2004. CRF was dichotomized into youth FITNESSGRAM® categories of “low” and “adequate” CRF. Logistic and quantile regression were used for a comprehensive analysis of associations, and variables with previously-reported associations with ALT were a priori included in the models.
Results from logistic regression suggested that youth with low CRF had 1.5 times the odds of having an ALT>30 than youth with adequate CRF, although the association was not statistically significant (P=0.09). However, quantile regression demonstrated that youth with low CRF had statistically significantly higher ALT (+1.04, +1.05, and +2.57 U/L) at the upper end of the ALT distribution (80th, 85th, and 90th percentiles, respectively) than youth with adequate CRF. For every 1-cm increase in WC, the odds of having an ALT>30 increased by 1.06 (P<0.001), and the strength of this association increased across the ALT distribution.
Future studies should examine whether interventions to improve CRF can decrease hepatic fat and liver enzyme concentrations in youth with ALT ≥80th percentile or in youth diagnosed with NAFLD.
Adolescents; Exercise; Metabolic Syndrome X; Non-alcoholic Fatty Liver Disease
To examine the relationship between estimated maximal cardiorespiratory fitness (CRF) and metabolic syndrome (MetS).
Aerobics Center Longitudinal Study (N=38,659) participants examined between 1979–2006.
We performed a cross-sectional analysis of participants to examine CRF levels defined as low (lower 20%), moderate (middle 40%) and high (upper 40%) of age/gender specific distributions versus NCEP derived MetSyn expressed as a summed z-score continuous variable. We used a general linear model for continuous variables, chi-square for distribution of categorical variables, and multiple linear regression for single and cumulative MetS scores adjusted for BMI, smoking status, alcohol intake and family history of cardiovascular disease.
We observed significant inverse trends for MetS vs. CRF in both genders (p-for-trend, < 0.001). CRF associations vs. individual components were: Waist circumference (men, β= −0.14, r2 = 0.78; women, β= −0.04, r2 = 0.71), triglycerides (men, β= −0.29, r2 = 0.18; women, β= −0.17, r2 = 0.18), HDL-cholesterol (men, β= 0.25, r2 = 0.17; women, β= 0.08, r2 = 0.19), fasting glucose (men, β= −0.09, r2 = 0.09; women, β= 0.09, r2 = 0.01), systolic blood pressure (men, β= −0.09, r2 = 0.09; women, β= −0.01, r2 = 0.21), and diastolic blood pressure (men, β= −0.07, r2 = 0.12; women, β= −0.05, r2 = 0.14). All associations except for systolic blood pressure (both genders) and glucose (women) are significant (p<0.001).
CRF demonstrated a strong inverse relationship with MetS in both genders with the strongest single associative component being waist circumference.
Metabolic syndrome; exercise; fitness; syndrome X
To evaluate the association of body adiposity index (BAI) with all-cause and cardiovascular disease (CVD) mortality risk.
Design and Methods
The current analysis comprised 19 756 adult men who enrolled in the Aerobics Centre Longitudinal Study and completed a baseline examination during 1988-2002. All-cause and CVD mortality was registered till December 31, 2003.
During an average follow-up of 8.3 years (163 844 man-years), 353 deaths occurred (101 CVD deaths). Age- and examination year-adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for all-cause mortality risk were higher for men with high values of BMI (HR = 1.63, 95% CI = 1.19–2.23), waist circumference (1.55, 1.22-1.96) and percentage of body fat (%BF) (1.36, 1.04-1.31), but not for men with high values of BAI (1.28, 0.98-1.66). The HRs for CVD mortality risks were higher for men with high values in all adiposity measures (HRs ranged from 1.73 to 2.06). Most of these associations, however, became nonsignificant after adjusting for multiple confounders including cardiorespiratory fitness.
BAI is not a better predictor of all-cause and CVD mortality risk than BMI, waist circumference or %BF.
Adiposity; body mass index; mortality; adults
Current knowledge on the prognosis of metabolically healthy but obese phenotype is limited due to the exclusive use of the body mass index to define obesity and the lack of information on cardiorespiratory fitness. We aimed to test the following hypotheses: (i) metabolically healthy but obese individuals have a higher fitness level than their metabolically abnormal and obese peers; (ii) after accounting for fitness, metabolically healthy but obese phenotype is a benign condition, in terms of cardiovascular disease and mortality.
Methods and results
Fitness was assessed by a maximal exercise test on a treadmill and body fat per cent (BF%) by hydrostatic weighing or skinfolds (obesity = BF% ≥25 or ≥30%, men or women, respectively) in 43 265 adults (24.3% women). Metabolically healthy was considered if meeting 0 or 1 of the criteria for metabolic syndrome. Metabolically healthy but obese participants (46% of the obese subsample) had a better fitness than metabolically abnormal obese participants (P < 0.001). When adjusting for fitness and other confounders, metabolically healthy but obese individuals had lower risk (30–50%, estimated by hazard ratios) of all-cause mortality, non-fatal and fatal cardiovascular disease, and cancer mortality than their metabolically unhealthy obese peers; while no significant differences were observed between metabolically healthy but obese and metabolically healthy normal-fat participants.
(i) Higher fitness should be considered a characteristic of metabolically healthy but obese phenotype. (ii) Once fitness is accounted for, the metabolically healthy but obese phenotype is a benign condition, with a better prognosis for mortality and morbidity than metabolically abnormal obese individuals.
Cardiovascular diseases; Heart diseases; Metabolic syndrome; Mortality; Obesity; Physical fitness