Methodological limitations compromise the validity of U.S. nutritional surveillance data and the empirical foundation for formulating dietary guidelines and public health policies.
Evaluate the validity of the National Health and Nutrition Examination Survey (NHANES) caloric intake data throughout its history, and examine trends in the validity of caloric intake estimates as the NHANES dietary measurement protocols evolved.
Validity of data from 28,993 men and 34,369 women, aged 20 to 74 years from NHANES I (1971–1974) through NHANES 2009–2010 was assessed by: calculating physiologically credible energy intake values as the ratio of reported energy intake (rEI) to estimated basal metabolic rate (BMR), and subtracting estimated total energy expenditure (TEE) from NHANES rEI to create ‘disparity values’.
Main Outcome Measures
1) Physiologically credible values expressed as the ratio rEI/BMR and 2) disparity values (rEI–TEE).
The historical rEI/BMR values for men and women were 1.31 and 1.19, (95% CI: 1.30–1.32 and 1.18–1.20), respectively. The historical disparity values for men and women were −281 and −365 kilocalorie-per-day, (95% CI: −299, −264 and −378, −351), respectively. These results are indicative of significant under-reporting. The greatest mean disparity values were −716 kcal/day and −856 kcal/day for obese (i.e., ≥30 kg/m2) men and women, respectively.
Across the 39-year history of the NHANES, EI data on the majority of respondents (67.3% of women and 58.7% of men) were not physiologically plausible. Improvements in measurement protocols after NHANES II led to small decreases in underreporting, artifactual increases in rEI, but only trivial increases in validity in subsequent surveys. The confluence of these results and other methodological limitations suggest that the ability to estimate population trends in caloric intake and generate empirically supported public policy relevant to diet-health relationships from U.S. nutritional surveillance is extremely limited.
Studies of physical activity and incidence of physician-diagnosed depression have been limited to a single estimate of self-reported physical activity exposure, despite follow-up periods lasting many years.
To examine longitudinal change in cardiorespiratory fitness, an objective marker of habitual physical activity, and incident depression complaints made to a physician.
Cardiorespiratory fitness assessed at four clinic visits between 1971 and 2006, each separated by an average of 2–3 years, was used to objectively measure cumulative physical activity exposure in cohorts of 7936 men and 1261 women, aged 20–85 years, from the Aerobics Center Longitudinal Study who did not complain of depression at their first clinic visit in 1971–2003. Data were analyzed in August 2010.
Across subsequent visits, there were 446 incident cases in men and 153 cases in women. After adjustment for age, time between visits, BMI at each visit, and fitness at Visit 1, each 1-minute decline in treadmill endurance (i.e., a decline in cardiorespiratory fitness of approximately 1 half-MET) between ages 51 and 55 years in men and ages 53 and 56 years in women, increased the odds of incident depression complaints by approximately 2% and 9.5%, respectively. The increased odds remained significant but were attenuated to 1.3% and 5.4% after further adjustment at each visit for smoking, alcohol use, chronic medical conditions, anxiety, and sleep problems.
Maintenance of cardiorespiratory fitness during late middle-age, when decline in fitness typically accelerates, helps protect against the onset of depression complaints made to a physician.
Physical activity may protect against breast cancer. Few prospective studies have evaluated breast cancer mortality in relation to cardiorespiratory fitness, an objective marker of physiologic response to physical activity habits.
We examined the association between cardiorespiratory fitness and risk of death from breast cancer in the Aerobics Center Longitudinal Study. Women (N=14,811), aged 20 to 83 years with no prior breast cancer history, received a preventive medical examination at the Cooper Clinic in Dallas, TX, between 1970 and 2001. Mortality surveillance was completed through December 31, 2003. Cardiorespiratory fitness was quantified as maximal treadmill exercise test duration and was categorized for analysis as low (lowest 20% of exercise duration), moderate (middle 40%), and high (upper 40%). At baseline, all participants were able to complete the exercise test to at least 85% of their age-predicted maximal heart rate.
A total of 68 breast cancer deaths occurred during follow-up (mean=16 years). Age-adjusted breast cancer mortality rates per 10,000 woman-years were 4.4, 3.2, and 1.8 for low, moderate, and high cardiorespiratory fitness groups, respectively (trend P = 0.008). After further controlling for body mass index, smoking, drinking, chronic conditions, abnormal exercise electrocardiogram responses, family history of breast cancer, oral contraceptive use, and estrogen use, hazard ratios (95% CI) for breast cancer mortality across incremental cardiorespiratory fitness categories were 1.00 (referent), 0.67 (0.35–1.26), 0.45 (0.22–0.95); trend P = 0.04.
These results indicate that cardiorespiratory fitness is associated with a reduced risk of dying from breast cancer in women.
Epidemiology; Prevention; Death from breast cancer; Physical activity
We examined the associations between muscular strength, markers of overall and central adiposity and cancer mortality in men.
Prospective cohort study including 8,677 men aged 20-82 years followed from 1980 to 2003. Participants were enrolled in The Aerobics Centre Longitudinal Study, the Cooper Clinic in Dallas, Texas, U.S. Muscular strength was quantified by combining 1-repetition maximal measures for leg and bench presses. Adiposity was assessed by body mass index (BMI), percent body fat, and waist circumference.
Cancer death rates per 10,000 person-years adjusted for age and examination year were: 17.5, 11.0, and 10.3 across incremental thirds of muscular strength (P=0.001); 10.9, 13.4, and 20.1 across BMI groups of 18.5-24.9, 25.0-29.9, and ≥30kg/m2, respectively (P=0.008); 11.6 and 17.5 for normal (<25%) and high percent body fat (≥25%), respectively (P=0.006); and 12.2 and 16.7 for normal (≤102 cm) and high waist circumference (>102 cm), respectively (P=0.06). After adjusting for additional potential confounders, hazard ratios (95% confidence intervals) were 1.00 (referent), 0.65 (0.47-0.90), and 0.61 (0.44-0.85) across incremental thirds of muscular strength, respectively (P=0.003 for linear trend). Further adjustment for BMI, percent body fat, waist circumference, or cardiorespiratory fitness had little effect on the association. The associations of BMI, percent body fat, or waist circumference with cancer mortality did not persist after further adjusting for muscular strength (all P≥0.1).
Higher levels of muscular strength are associated with lower cancer mortality risk in men, independent of clinically established measures of overall and central adiposity, and other potential confounders.
Muscular strength; obesity; cancer; cardiorespiratory fitness; resistance exercise
We modeled the age-related trajectory of glucose and determined if cardiorespiratory fitness altered the trajectory in a cohort of men from the Aerobics Center Longitudinal Study.
10,092 men free of diagnosed diabetes, CVD, and cancer, aged 20 to 90 years, completed from 2 to 21 health examinations between 1977 and 2005. Cardiorespiratory fitness was measured by a maximal treadmill exercise test and normalized for age. The covariates included waist circumference, hypertension, elevated cholesterol, smoking behavior and physical activity.
Linear mixed models regression analysis showed that fasting glucose increased at a linear rate with aging. Glucose increased at a yearly rate of 0.17 mg/dL (95% confidence interval: 0.16, 0.19). Fitness had little influence on the aging glucose trajectory below age 35, but significantly influenced the trend after age 35 (P for interaction <0.001). The aging-related glucose increases in low fit men (0.25 mg/dL per year) was higher than average fit (0.15 mg/dL per year) and high fit (0.13 mg/dL per year) men.
The aging-related glucose increases in low fit men was nearly double that of high fit men. Our results may suggest that it is possible to delay the age-related glucose impairment through increasing one’s fitness.
Fasting glucose; aging; physical fitness
Strong evidence shows that physical inactivity increases the risk of many adverse health conditions, including the world’s major non-communicable diseases (NCDs) of coronary heart disease (CHD), type 2 diabetes, and breast and colon cancers, and shortens life expectancy. Because much of the world’s population is inactive, this presents a major public health problem. We aimed to quantify the impact of physical inactivity on these major NCDs by estimating how much disease could be averted if those inactive were to become active and to estimate gain in life expectancy, at the population level.
Using conservative assumptions, we calculated population attributable fractions (PAF) associated with physical inactivity for each of the major NCDs, by country, to estimate how much disease could be averted if physical inactivity were eliminated, and used life table analysis to estimate gains in life expectancy of the population.
Worldwide, we estimate that physical inactivity is responsible for 6% of the burden of disease from CHD (range: 3.2% in South-east Asia to 7.8% in the Eastern Mediterranean region); 7% of type 2 diabetes (3.9% to 9.6%), 10% of breast cancer (5.6% to 14.1%), and 10% of colon cancer (5.7% to 13.8%). Inactivity is responsible for 9% of premature mortality (5.1% to 12.5%), or >5.3 of the 57 million deaths that occurred worldwide in 2008. If inactivity were not eliminated, but decreased instead by 10% or 25%, >533,000 and >1.3 million deaths, respectively, may be averted each year. By eliminating physical inactivity, life expectancy of the world’s population is estimated to increase by 0.68 (0.41 to 0.95) years.
Physical inactivity has a major health impact on the world. Elimination of physical inactivity would remove between 6% and 10% of the major NCDs of CHD, type 2 diabetes, and breast and colon cancers, and increase life expectancy.
To determine if time spent in screen-based sedentary behavior is associated with change in cardiorespiratory fitness (CRF) levels in children from age 11 to 13, adjusting for vigorous physical activity (VPA).
Participants were children (n=2,097) enrolled in the control arm of the HEALTHY Study, who performed 20m shuttle run tests at ages 11 and 13. Self-reported screen time was used as a measure of sedentary behavior. Longitudinal quantile regression was used to model the influence of predictors on changes at the 10th, 25th, 50th, 75th and 90th shuttle run lap percentiles. Screen time (hrs/d) was the main predictor and adjustment was also made for VPA, body mass index and household education.
In boys, more screen time was associated with fewer shuttle run laps completed from age 11 to 13 at the 25th, 50th and 75th shuttle run lap percentiles; the strongest association was at the 75th shuttle run percentile (-0.57, 95% CI: -0.93 to -0.21). In girls, more screen time was associated with fewer shuttle run laps completed from age 11 to 13 at the 50th, 75th and 90th shuttle run lap percentiles; the strongest association was at the 90th shuttle run percentile (-0.65, -1.01 to -0.30). Borderline negative associations were found between screen time and shuttle run laps at the 10th shuttle run percentile in boys and girls (-0.28, -0.57 to 0.01 and -0.17, -0.41 to 0.06, respectively).
More screen time was associated with lower CRF from age 11 to 13, independent of VPA. However, the association was weakest at the lower tail of the CRF distribution.
aerobic; shuttle run; pacer; television; computer; longitudinal
Background. Prior studies suggest that weight satisfaction may preclude changes in behavior that lead to healthier weight among individuals who are overweight or obese. Objective. To gain a better understanding of complex relationships between weight satisfaction, weight-related health behaviors, and health outcomes. Design. Cross-sectional analysis of data from the Aerobics Center Longitudinal Study (ACLS). Participants. Large mixed-gender cohort of primarily white, middle-to-upper socioeconomic status (SES) adults with baseline examination between 1987 and 2002 (n = 19,003).
Main Outcome Variables. Weight satisfaction, weight-related health behaviors, chronic health conditions, and clinical health indicators. Statistical Analyses Performed. Chi-square test, t-tests, and linear and multivariate logistic regression. Results. Compared to men, women were more likely to be dieting (32% women; 18% men) and had higher weight dissatisfaction. Men and women with greater weight dissatisfaction reported more dieting, yo-yo dieting, and snacking and consuming fewer meals, being less active, and having to eat either more or less than desired to maintain weight regardless of weight status. Those who were overweight or obese and dissatisfied with their weight had the poorest health. Conclusion. Greater satisfaction with one's weight was associated with positive health behaviors and health outcomes in both men and women and across weight status groups.
To describe longitudinal patterns of objectively measured sedentary behavior from age 12 to 16.
Children participating in the Avon Longitudinal Study of Parents and Children wore accelerometers for one week at age 12, 14 and 16. Participants included boys (n=2591) and girls (n=2845) living in a single geographic location in the U.K. (Bristol). Total minutes per day spent in sedentary behavior, and time spent in blocks of sedentary behavior lasting 10–19 minutes, 20–29 minutes and 30+ minutes are described. Growth curve models were used to determine the rate of change in sedentary behavior from age 12 to 16.
At age 12 the boys and girls, on average, were sedentary for 418.0 (67.7) and 436.6 (64.0) minutes per day respectively, and sedentary behavior increased over time to 468.0 (74.3) and 495.6 (68.9) minutes per day at age 14, and to 510.4 (76.6) and 525.4 (67.4) minutes per day at age 16. Growth curve analyses found that total sedentary behavior increased at a rate of 19.5 (0.7) and 22.8 (0.7) minutes per day per year for the boys and girls respectively. The absolute mean increase in total sedentary behavior (+92.4 min/d and +88.8 min/d for the boys and girls respectively) closely matched the mean decrease in light physical activity (−82.2 min/d and −82.9 min/d for the boys and girls respectively, from age 12 to 16. Time spent in continuous sedentary behavior lasting 30+ minutes increased by 121% from age 12 to 16.
Sedentary behavior increased with age, at the expense of light physical activity. The increase in sedentary behavior lasting 30+ minutes in duration contributed greatly to the increase in total sedentary behavior.
Children; adolescents; longitudinal; patterns; descriptive
Type-2 diabetes is associated with increased risk of cardiovascular disease and elevated C-reactive protein levels (CRP). Aerobic exercise training has been shown to improve CRP, however there are limited data evaluating the effect of other exercise training modalities (aerobic, resistance or combination training) in individuals with type-2 diabetes.
Participants (n=204) were randomized to an aerobic exercise (aerobic), resistance exercise (resistance) or a combination of both (combination) for nine months. CRP was evaluated at baseline and at follow-up.
Baseline CRP was correlated with fat mass, waist circumference, BMI, and VO2 peak (p<0.05). CRP was not reduced following aerobic (0.16 mg·L -1, 95% CI: −1.0, 1.3), resistance (−0.03 mg·L -1, 95% CI: −1.1, 1.0) or combination (−0.49 mg·L -1, 95% CI: −1.5 to 0.6) training compared to control (0.35 mg·L -1, 95% CI: −1.0, 1.7). Change in fasting glucose (r=0.20, p=0.009), glycated hemoglobin (HbA1C) (r=0.21 p=0.005), and fat mass (r=0.19, p=0.016) were associated with reductions in CRP, but not change in fitness or weight (p > 0.05). There were significant trends observed for CRP among tertiles of change in HbA1C (p=0.009) and body fat (p=0.040).
Aerobic, resistance or a combination of both did not reduce CRP levels in individuals with type-2 diabetes. However, exercise related improvements in HbA1C, fasting glucose, and fat mass were associated with reductions in CRP.
Inflammation; Aerobic Training; Resistance Training; Hemoglobin A1C; Adiposity; Fitness
Instrumental activities of daily living (IADLs) are tasks that are necessary for independent community living. These tasks often require intact physical and cognitive function, the impairment of which may adversely affect health in older adults. In the current study, we examined the association between IADL impairment and incident heart failure (HF) in community-dwelling older adults.
Methods and results
Of the 5795 community-dwelling adults, aged ≥65 years, in the Cardiovascular Health Study, 5511 had data on baseline IADL and were free of prevalent HF. Of these, 1333 (24%) had baseline IADL impairment, defined as self-reported difficulty with one or more of the following tasks: using the telephone, preparing food, performing light and heavy housework, managing finances, and shopping. Propensity scores for IADL impairment, estimated for each of the 5511 participants, were used to assemble a cohort of 1038 pairs of participants with and without IADL impairment who were balanced on 42 baseline characteristics. Centrally adjudicated incident HF occurred in 26% and 21% of matched participants with and without IADL impairment, respectively, during >12 years of follow-up [matched hazard ratio (HR) 1.33; 95% confidence interval (CI) 1.11–1.59; P = 0.002]. Unadjusted and multivariable-adjusted HRs for incident HF before matching were 1.77 (95% CI 1.56–2.01; P < 0.001) and 1.33 (95% CI 1.15–1.54; P < 0.001), respectively. IADL impairment was also associated with all-cause mortality (matched HR 1.19; 95% CI 1.06–1.34; P = 0.004).
Among community-dwelling older adults free of baseline HF, IADL impairment is a strong and independent predictor of incident HF and mortality.
Instrumental activities of daily living; Incident heart failure; Propensity score
While combination antiretroviral therapy has extended the life expectancy of those infected with human immunodeficiency virus (HIV), there is a high prevalence of comorbidities that increase the risk of cardiovascular morbidity and mortality among people living with HIV/AIDS (PLWHA). The side effects associated with antiretroviral therapy (ART) lead to multiple metabolic disorders, making the management of these metabolic issues and risk of cardiovascular disease (CVD) in those treated with ART a critical issue. Clinical research trials, primarily clinical exercise, rarely include this population due to unique challenges in research methods with underserved minority populations living with a life threatening illness like HIV/AIDS. This paper describes the rationale and design of a randomized clinical trial evaluating the feasibility of a home-based exercise program designed to increase physical activity (PA) and reduce the risk of CVD in PLWHA.
PLWHA being treated with ART will be randomly assigned to one of two groups: a home-based PA intervention or standard care. All participants will receive an educational weight loss workbook and pedometer for self-monitoring of PA. Only those in the intervention group will receive additional elastic Thera-bands® for strength training and behavioral telephone based coaching.
This study will evaluate the feasibility of a home-based program designed to increase PA among PLWHA. Further, it will evaluate the effectiveness of such a program to decrease modifiable risk factors for CVD as a secondary outcome. This study was funded by the NIH/NINR R21 Grant 1R21NRO11281.
Clinical Trial Identifier NCT01377064
Randomized trial; Cardiovascular disease; HIV; Physical activity; Self care; Study design
Abnormally elevated exercise blood pressure is associated with increased risk of cardiovascular disease. Aerobic exercise training has been shown to reduce exercise blood pressure. However, it is unknown if these improvements occur in a dose dependent manner. The purpose of the present study is to determine the effect of different doses of aerobic exercise training on exercise blood pressure in obese postmenopausal women.
Participants (n=404) were randomized to one of 4 groups: 4, 8, or 12 kilocalories per kilogram of energy expenditure per week (kcal/kg/week) or the non-exercise control group for 6 months. Exercise blood pressure was obtained during the 50 watts stage of a cycle ergometer maximal exercise test.
There was a significant reduction in systolic blood pressure at 50 watts in the 4 kcal/kg/week (−10.9 mmHg, p< 0.001), 8 kcal/kg/week (−9.9 mmHg, p= 0.022), and 12 kcal/kg/week (−13.7 mmHg, p<0.001) compared to control (−4.2 mmHg). Only the highest exercise training dose significantly reduced diastolic blood pressure (−4.3 mmHg, p= 0.033) compared to control. Additionally, resting blood pressure was not altered following exercise training (p>0.05) compared to control, and was not associated with changes in exercise systolic (r=0.09, p=0.09) or diastolic (r=0.10, p=0.08) blood pressure.
Aerobic exercise training reduces exercise blood pressure and may be more modifiable than changes in resting blood pressure. A high dose of aerobic exercise is recommended to successfully reduce both exercise systolic and diastolic blood pressure, and therefore may attenuate the CVD risk associated with abnormally elevated exercise blood pressure.
Postmenopausal; Exercise Training; Exercise Blood Pressure; Dose Response; Hypertension
Low serum bilirubin levels have been associated with increased risk for cardiovascular disease, and recent data suggest that lower body fat and reductions in weight are associated with higher bilirubin levels. However, it is unknown if exercise training can increase bilirubin levels and whether a higher dose of exercise will further increase bilirubin levels compared to a lower dose.
The primary aim of our current report is to examine whether exercise dose affects bilirubin levels in obese postmenopausal women from the Dose Response to Exercise in Women (DREW) trial. In addition, we evaluated whether changes in fitness, insulin sensitivity, and waist circumference associated with exercise training were associated with change in bilirubin levels.
Participants (n= 419) were randomized to the control group or 4, 8 and 12 kilocalories per kilogram per week (KKW) of exercise training at an intensity of 50% of aerobic capacity. Total bilirubin levels were evaluated at baseline and at follow-up.
Exercise training significantly increased serum bilirubin levels only in the 12 KKW group (0.044 mg/dL, p=0.026) compared to control (0.004 mg/dL). Subgroup analyses showed that there was a significant increase in bilirubin levels in participants in the 12 KKW group (0.076 mg/dL) who were classified as insulin resistant (HOMA> 2.6), compared to insulin resistant control participants (0.018 mg/dL) (p=0.028).
Our findings suggest that high doses of exercise training are necessary to significantly increase bilirubin levels in previously sedentary postmenopausal women especially in individuals with impaired glucose metabolism.
Antioxidant capacity; physical activity; dose-response; postmenopausal
To analyze the relationship of ideal cardiovascular health to disease-specific death.
Patients and Methods
We used data from the Aerobics Center Longitudinal Study from October 9, 1987, to March 3, 1999, to estimate the prevalence of ideal cardiovascular health in 11,993 individuals (24.3% women) and to examine its relationship with deaths from all causes, cardiovascular disease (CVD), and cancer.
During a mean follow-up of 11.6 years, 305 deaths occurred: 70 (23.0%) from CVD and 127 (41.6%) from cancer. In the entire cohort, only 29 individuals (0.2%) had 7 ideal metrics. After adjusting for age, sex, examination year, alcohol intake, and parental history of CVD, risk of death due to CVD was 55% lower in those participants who met 3 or 4 ideal metrics (hazard ratio, 0.45; 95% confidence interval, 0.27-0.77) and 63% lower in those with 5 to 7 ideal metrics (hazard ratio, 0.37; 95% confidence interval, 0.15-0.95), compared with those who met 0 to 2 ideal metrics. Although not significant, there was also a trend toward lower risk of death due to all causes across incremental numbers of ideal metrics. No association was observed for deaths due to cancer.
The prevalence of ideal cardiovascular health was extremely low in a middle-aged cohort of men and women recruited between 1987 and 1999. The American Heart Association construct reflects well the subsequent risk of CVD, as reflected by graded CVD mortality in relation to the number of ideal metrics.
ACLS, Aerobics Center Longitudinal Study; AHA, American Heart Association; BMI, body mass index; CVD, cardiovascular disease; ICD, International Classification of Diseases; MET, metabolic equivalent; NHANES, National Health and Nutrition Examination Survey
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.
Our group has shown a positive dose-response in maximal cardiorespiratory exercise capacity (VO2max) and heart rate variability (HRV) to 6 months of exercise training but no improvement in VO2max for women ≥60 years. Here, we examine the HRV response to exercise training in postmenopausal women younger and older than 60 years.
We examined 365 sedentary, overweight, hypertensive, postmenopausal women randomly assigned to sedentary control or exercise groups exercising at 50% (4 kcal/kg/week, [KKW]), 100% (8 KKW) and 150% (12 KKW) of the National Institutes of Health (NIH) Consensus Development Panel physical activity guidelines. Primary outcomes included time and frequency domain indices of HRV.
Overall, our analysis demonstrated a significant improvement in parasympathetic tone (rMSSD and high frequency power) for both age strata at 8 KKW and 12 KKW. For rMSSD, the age-stratified responses were: control, <60 years, 0.20 ms, 95% confidence interval (CI)−2.40, 2.81; ≥60 years, 0.07 ms, 95% CI −3.64, 3.79; 4 KKW, <60 years, 3.67 ms, 95% CI 1.55, 5.79; ≥60 years, 1.20 ms, 95% CI −1.82, 4.22; 8-KKW, <60 years, 3.61 ms, 95% CI 0.88, 6.34; ≥60 years, 5.75 ms, 95% CI 1.89, 9.61; and 12-KKW, <60 years, 5.07 ms, 95% CI 2.53, 7.60; ≥60 years, 4.28 ms, 95% CI 0.42, 8.14.
VO2max and HRV are independent risk factors for cardiovascular disease (CVD) mortality. Despite no improvement in VO2max, parasympathetic indices of HRV increased in women ≥60 years. This is clinically important, as HRV has important CVD risk and neurovisceral implications beyond cardiorespiratory function.
Our aim was to examine the independent and combined associations of changes in fitness and fatness with the subsequent incidence of the cardiovascular disease (CVD) risk factors of hypertension, metabolic syndrome, and hypercholesterolemia.
The relative and combined contributions of fitness and fatness to health are controversial, and few studies are available on the associations of changes in fitness and fatness with the development of CVD risk factors.
We followed 3,148 healthy adults who received at least three medical examinations. Fitness was determined by a maximal treadmill test. Fatness was expressed by percent body fat and body mass index. Changes in fitness and fatness between the first and second examinations were categorized into loss, stable, or gain groups.
During the 6-year follow-up after the second examination, 752, 426, and 597 adults developed hypertension, metabolic syndrome, and hypercholesterolemia, respectively. Maintaining or improving fitness was associated with lower risk of developing each outcome, whereas increasing fatness was associated with higher risk of developing each outcome, after adjusting for possible confounders and fatness or fitness for each other (all p for trend <0.05). In the joint analyses, the increased risks associated with fat gain appeared to be attenuated, although not completely eliminated, when fitness was maintained or improved. In addition, the increased risks associated with fitness loss were also somewhat attenuated when fatness was reduced.
Both maintaining or improving fitness and preventing fat gain are important to reduce the risk of developing CVD risk factors in healthy adults.
cardiorespiratory fitness; body fatness; hypertension; metabolic syndrome; hypercholesterolemia
This study evaluated the reliability and criterion validity of the Mywellness Key accelerometer (MWK) using treadmill protocols and indirect calorimetry.
Twenty-five participants completed two four-stage 20-minute treadmill protocols while wearing two MWK accelerometers. Reliability was assessed using raw counts. Validity was assessed by comparing the estimated VO2 calculated from the MWK with values from respiratory gas exchange.
Good overall and point estimates of reliability were found for the MWK (all intraclass correlations > 0.93). Generalizability theory coefficients showed lower values for running speed (0.70) versus walking speed (all > 0.84), with the majority of the overall percentage of variability derived from the participant (68%–88% of the total 100%). Acceptable validity was found overall (Pearson’s r = 0.895–0.902, P < 0.0001), with an overall mean absolute error of 16.22% and a coefficient of variance of 16.92%. Bland-Altman plots showed an overestimation of energy expenditure during the running speed, but total kilocalories were underestimated during the protocol by approximately 10%.
Good validity was found during light and moderate walking, while running was slightly overestimated. The MWK may be useful for clinicians and researchers interested in promotion or assessment of physical activity.
physical activity; accelerometer; health monitor
This study aimed to compare the levels of objectively-measured sedentary behavior in children attending Montessori preschools with those attending traditional preschools.
The participants in this study were preschool children aged 4 years old who were enrolled in Montessori and traditional preschools. The preschool children wore ActiGraph accelerometers. Accelerometers were initialized using 15-second intervals and sedentary behavior was defined as <200 counts/15-second. The accelerometry data were summarized into the average minutes per hour spent in sedentary behavior during the in-school, the after-school, and the total-day period. Mixed linear regression models were used to determine differences in the average time spent in sedentary behavior between children attending traditional and Montessori preschools, after adjusting for selected potential correlates of preschoolers’ sedentary behavior.
Children attending Montessori preschools spent less time in sedentary behavior than those attending traditional preschools during the in-school (44.4. min/hr vs. 47.1 min/hr, P = 0.03), after-school (42.8. min/hr vs. 44.7 min/hr, P = 0.04), and total-day (43.7 min/hr vs. 45.5 min/hr, P = 0. 009) periods. School type (Montessori or traditional), preschool setting (private or public), socio-demographic factors (age, gender, and socioeconomic status) were found to be significant predictors of preschoolers’ sedentary behavior.
Levels of objectively-measured sedentary behavior were significantly lower among children attending Montessori preschools compared to children attending traditional preschools. Future research should examine the specific characteristics of Montessori preschools that predict the lower levels of sedentary behavior among children attending these preschools compared to children attending traditional preschools.
Sedentary behavior; Preschool; Montessori; Accelerometer
Physical activity (PA) is a key component of healthy lifestyle and disease prevention. In contrast, physical inactivity accounts for a significant proportion of premature deaths worldwide. Physicians are in a critical position to help patients develop healthy lifestyles by actively counseling on PA. Sports medicine physicians, with their focus on sports and exercise medicine are uniquely trained to provide such expertise to patients, learners and colleagues. To succeed, physicians need clinical tools and processes that support PA assessment and counseling. Linking patients to community resources, and specifically to health and fitness professionals is a key strategy. Efforts should be made to expand provider education during medical school, residency and fellowship training, and continuing medical education. Lastly, physically active physicians are more likely to counsel patients to be active. A key message for the sports medicine community is the importance of serving as a positive PA role model.
Physical activity promotion in primary care; Sports and nutrition
Reduced gait speed is associated with falls, late-life disability, hospitalization/institutionalization and cardiovascular morbidity and mortality. Aging is also accompanied by a widening of pulse pressure (PP) that contributes to ventricular-vascular uncoupling. The purpose of this study was to test the hypothesis that PP is associated with long-distance gait speed in community-dwelling older adults in the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P) study.
Brachial blood pressure and 400-meter gait speed (average speed maintained over a 400-meter walk at “usual” pace) were assessed in 424 older adults between the ages of 70–89 yrs at risk for mobility disability (mean age = 77 yrs; 31% male). PP was calculated as systolic blood pressure (BP) – diastolic BP.
Patients with a history of heart failure and stroke (n = 42) were excluded leaving 382 participants for final analysis. When categorized into tertiles of PP, participants within the highest PP tertile had significantly slower gait speed than those within the lowest PP tertile (p<0.05). Following stepwise multiple regression, PP was significantly and inversely associated with 400-meter gait speed (p<0.05). Other significant predictors of gait speed included: handgrip strength, body weight, age and history of diabetes mellitus (p<0.05). Mean arterial pressure, systolic BP and diastolic BP were not predictors of gait speed.
Pulse pressure is associated long-distance gait speed in community-dwelling older adults. Vascular senescence and altered ventricular-vascular coupling may be associated with the deterioration of mobility and physical function in older adults.
Elevated serum bilirubin has been suggested to reduce the risk of mortality. Cardiorespiratory fitness (CRF) has also been reported to have inverse association with all-cause and cardiovascular disease (CVD) mortality. The association between serum bilirubin, all-cause and CVD mortality and the effect of CRF on the observed association was investigated. A total of 1279 men, ages 30-82 years old, who underwent baseline medical examinations during 1974 to 1997 at the Cooper Clinic in Dallas, Texas. During an average of 17 years follow-up, 698 men died, with 253 deaths due to CVD (36%). Men in the highest bilirubin quartiles had significantly lower risk of all-cause mortality compared to men in the lowest quartiles (p for trend=0.0043), after adjusting for age and examination year. This inverse association remained significant after further adjustment for known confounders (p for trend=0.0018). Additional adjustment for treadmill time attenuated the association (p trend=0.0090). Similar patterns of association were observed between serum bilirubin quartiles and CVD mortality. CRF was inversely associated with all-cause mortality (p for trend < .0001) after adjusting for age and examination year. This inverse association also was observed after further adjusting for known confounders (p for trend=0.0004). After additional adjustment for serum bilirubin, the association between the CRF and all-cause mortality remained significant (p for trend = 0.0012). All-cause mortality and CVD mortality were significantly lower among men in the moderate to high fit quartiles in both the low and high bilirubin groups. In Conclusion both serum bilirubin level and CRF level were strongly and independently associated with all-cause and CVD mortality.
serum bilirubin; cardiorespiratory fitness; cardiovascular disease; men; mortality