Conrad P. Earnest

Trends over 5 Decades in U.S. Occupation-Related Physical Activity and Their Associations with Obesity

Background The true causes of the obesity epidemic are not well understood and there are few longitudinal population-based data published examining this issue. The objective of this analysis was to examine trends in occupational physical activity during the past 5 decades and explore how these trends relate to concurrent changes in body weight in the U.S. Methodology/Principal Findings Analysis of energy expenditure for occupations in U.S. private industry since 1960 using data from the U.S. Bureau of Labor Statistics. Mean body weight was derived from the U.S. National Health and Nutrition Examination Surveys (NHANES). In the early 1960s almost half the jobs in private industry in the U.S. required at least moderate intensity physical activity whereas now less than 20% demand this level of energy expenditure. Since 1960 the estimated mean daily energy expenditure due to work related physical activity has dropped by more than 100 calories in both women and men. Energy balance model predicted weights based on change in occupation-related daily energy expenditure since 1960 for each NHANES examination period closely matched the actual change in weight for 40–50 year old men and women. For example from 1960–62 to 2003–06 we estimated that the occupation-related daily energy expenditure decreased by 142 calories in men. Given a baseline weight of 76.9 kg in 1960–02, we estimated that a 142 calories reduction would result in an increase in mean weight to 89.7 kg, which closely matched the mean NHANES weight of 91.8 kg in 2003–06. The results were similar for women. Conclusion Over the last 50 years in the U.S. we estimate that daily occupation-related energy expenditure has decreased by more than 100 calories, and this reduction in energy expenditure accounts for a significant portion of the increase in mean U.S. body weights for women and men.

Effects of Aerobic and Resistance Training on Hemoglobin A1c Levels in Patients With Type 2 Diabetes: A Randomized Controlled Trial

CONTEXT Exercise guidelines for individuals with diabetes include both aerobic and resistance training although few studies have directly examined this exercise combination. OBJECTIVE To examine the benefits of aerobic training alone, resistance training alone, and a combination of both on hemoglobin A(1c) (HbA(1c)) in individuals with type 2 diabetes. DESIGN, SETTING, AND PARTICIPANTS A randomized controlled trial in which 262 sedentary men and women in Louisiana with type 2 diabetes and HbA(1c) levels of 6.5% or higher were enrolled in the 9-month exercise program between April 2007 and August 2009. INTERVENTION Forty-one participants were assigned to the nonexercise control group, 73 to resistance training 3 days a week, 72 to aerobic exercise in which they expended 12 kcal/kg per week; and 76 to combined aerobic and resistance training in which they expended 10 kcal/kg per week and engaged in resistance training twice a week. Main Outcome Change in HbA(1c) level. Secondary outcomes included measures of anthropometry and fitness. RESULTS The study included 63.0% women and 47.3% nonwhite participants who were a mean (SD) age of 55.8 years (8.7 years) with a baseline HbA(1c) level of 7.7% (1.0%). Compared with the control group, the absolute mean change in HbA(1c) in the combination training exercise group was -0.34% (95% confidence interval [CI], -0.64% to -0.03%; P = .03). The mean changes in HbA(1c) were not statistically significant in either the resistance training (-0.16%; 95% CI, -0.46% to 0.15%; P = .32) or the aerobic (-0.24%; 95% CI, -0.55% to 0.07%; P = .14) groups compared with the control group. Only the combination exercise group improved maximum oxygen consumption (mean, 1.0 mL/kg per min; 95% CI, 0.5-1.5, P < .05) compared with the control group. All exercise groups reduced waist circumference from -1.9 to -2.8 cm compared with the control group. The resistance training group lost a mean of -1.4 kg fat mass (95% CI, -2.0 to -0.7 kg; P < .05) and combination training group lost a mean of -1.7 (-2.3 to -1.1 kg; P < .05) compared with the control group. CONCLUSIONS Among patients with type 2 diabetes mellitus, a combination of aerobic and resistance training compared with the nonexercise control group improved HbA(1c) levels. This was not achieved by aerobic or resistance training alone. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00458133.

Associations Between Cardiorespiratory Fitness and C-Reactive Protein in Men

Objective—This study examined the association between cardiorespiratory fitness and C-reactive protein (CRP), with adjustment for weight and within weight categories. Methods and Results—We calculated median and adjusted geometric mean CRP levels, percentages of individuals with an elevated CRP (≥2.00 mg/L), and odds ratios of elevated CRP across 5 levels of cardiorespiratory fitness for 722 men. CRP values were adjusted for age, body mass index, vitamin use, statin medication use, aspirin use, the presence of inflammatory disease, cardiovascular disease, and diabetes, and smoking habit. We found an inverse association of CRP across fitness levels (P for trend<0.001), with the highest adjusted CRP value in the lowest fitness quintile (1.64 [1.27 to 2.11] mg/L) and the lowest adjusted CRP value in the highest fitness quintile (0.70 [0.60 to 0.80] mg/L). Similar results were found for the prevalence of elevated CRP across fitness quintiles. We used logistic regression to model the adjusted odds for elevated CRP and found that compared with the referent first quintile, the second (odds ratio [OR] 0.43, 95% CI 0.22 to 0.85), third (OR 0.33, 95% CI 0.17 to 0.65), fourth (OR 0.23, 95% CI 0.12 to 0.47), and fifth (OR 0.17, 95% CI 0.08 to 0.37) quintiles of fitness had significantly lower odds of elevated CRP. Similar results were found when examining the CRP-fitness relation within categories of body fatness (normal weight, overweight, and obese) and waist girth (<102 or ≥102 cm). Conclusions—Cardiorespiratory fitness levels were inversely associated with CRP values and the prevalence of elevated CRP values in this sample of men from the Aerobics Center Longitudinal Study.

ISSN Exercise & Sport Nutrition Review: Research & Recommendations

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients.

Associations of muscle strength and fitness with metabolic syndrome in men

PURPOSE To examine the associations for muscular strength and cardiorespiratory fitness with the prevalence of metabolic syndrome among men. METHODS Participants were 8570 men (20-75 yr) for whom an age-specific muscular strength score was computed by combining the body weight adjusted one-repetition maximum measures for the leg press and the bench press. Cardiorespiratory fitness was quantified by age-specific maximal treadmill exercise test time. RESULTS Separate age and smoking adjusted logistic regression models revealed a graded inverse association for metabolic syndrome prevalence with muscular strength (beta = -0.37, P < 0.0001) and cardiorespiratory fitness (beta = -1.2, P < 0.0001). The association between strength and metabolic syndrome was attenuated (beta = -0.08, P < 0.01) when further adjusted for cardiorespiratory fitness. The association between cardiorespiratory fitness and metabolic syndrome was unchanged (beta = -1.2, P < 0.0001) after adjusting for strength. Muscular strength added to the protective effect of fitness among men with low (P trend = 0.0002) and moderate (P trend < 0.0001) fitness levels. Among normal weight (BMI < 25), overweight (BMI 25-30), and obese (BMI >or= 30) men, respectively, being strong and fit was associated with lower odds (73%, 69%, and 62% respectively, P < 0.0001) of having prevalent metabolic syndrome. CONCLUSIONS Muscular strength and cardiorespiratory fitness have independent and joint inverse associations with metabolic syndrome prevalence.

The Role of Exercise and Physical Activity in Weight Loss and Maintenance

This review explores the role of physical activity (PA) and exercise training (ET) in the prevention of weight gain, initial weight loss, weight maintenance, and the obesity paradox. In particular, we will focus the discussion on the expected initial weight loss from different ET programs, and explore intensity/volume relationships. Based on the present literature, unless the overall volume of aerobic ET is very high, clinically significant weight loss is unlikely to occur. Also, ET also has an important role in weight regain after initial weight loss. Overall, aerobic ET programs consistent with public health recommendations may promote up to modest weight loss (~2 kg), however the weight loss on an individual level is highly heterogeneous. Clinicians should educate their patients on reasonable expectations of weight loss based on their physical activity program and emphasize that numerous health benefits occur from PA programs in the absence of weight loss.

Profiles of sedentary behavior in children and adolescents:The US National Health and Nutrition Examination Survey, 2001-2006

OBJECTIVE To describe the prevalence of time spent in sedentary behaviors (e.g., TV/video and computer use) among youth in the US. METHODS The National Health and Nutrition Examination Survey (2001-06) provided data to examine sedentary behavior across age groups (2-5, 6-11, and 12-15 years of age), ethnic groups (European [EA], African [AA], and Mexican American [MA]), and body mass index (BMI) categories (normal weight, overweight, obese). RESULTS The sample included 8 707 (50.7% boys) children aged 2 to 15 years. Seventy percent of the sample was normal weight, 18.1% was overweight, and 11.5% was obese. The total proportion of young people engaged in TV/video viewing, computer use, and total screen time > or = 2 hours daily was 33.0%, 6.7%, and 47.3%, respectively. More boys (49.4%) than girls (45.0%); older (12-15 years: 56.0%) versus younger children (2-5 years: 35.3% and 6-11 years: 49.1%); AA (66.1%) versus EA (42.5%) and MA (46.1%); obese (58.5%) versus overweight (50.8%) versus normal weight (44.6%); and low and middle income (<

Exercise Dose and Quality of Life: A Randomized Controlled Trial

25 K: 51.4% and

Changes in Weight, Waist Circumference and Compensatory Responses with Different Doses of Exercise among Sedentary, Overweight Postmenopausal Women

25-45 K: 51.2%) versus high income (>

Exercise and the Cardiovascular System: Clinical Science and Cardiovascular Outcomes

45 K: 42.6%) children spent > or = 2 hours daily in screen time. CONCLUSION Nearly half (47%) of US children exceed > or = 2 hours/day of time in sedentary behavior. Further, it appears there are gender, age, ethnic, BMI-defined weight status, and income differences in exceeding > or = 2 hours/day in sedentary behavior. These results will be useful in planning targeted interventions at those populations with a higher prevalence of sedentary behavior.