A randomized controlled exercise training trial on insulin sensitivity in African American men: The ARTIIS study: Major category: study design, statistical design, study protocols.

BACKGROUND: Lack of regular physical activity at prescribed intensity levels is a modifiable risk factor for insulin resistance and the development of diabetes. African American men are at increased risk for developing diabetes and most African American men are not meeting the current recommended levels of physical activity. The primary objective of the Aerobic Plus Resistance Training and Insulin Resistance in African American Men (ARTIIS) study is to determine the effectiveness of an exercise training intervention aimed at reducing diabetes risk factors in African American men at risk for developing diabetes. METHODS: Insufficiently active 35-70 year old African American men with a family history of diabetes were eligible for the study. The 5-month randomized controlled trial assigns 116 men to an exercise training or healthy living control arm. The exercise training arm combines aerobic and resistance training according to the current national physical activity recommendations and is conducted in community (YMCA) facilities. The healthy living arm receives information promoting healthy lifestyle changes. OUTCOMES: Insulin response to an oral glucose load is the primary outcome measure, and changes in physiological parameters, cardiorespiratory fitness, strength, body composition, and psychological well-being comprise the secondary outcomes. CONCLUSIONS: The ARTIIS study is one of the first adequately powered, rigorously designed studies to investigate the effects of an aerobic plus resistance exercise training program and to assess adherence to exercise training in community facilities, in African American men.

Challenges to recruitment and retention of African Americans in the gene-environment trial of response to dietary interventions (GET READI) for heart health.

In this paper, challenges to recruiting African Americans specifically for a dietary feeding trial are examined, learning experiences gained and suggestions to overcome these challenges in future trials are discussed. A total of 333 individuals were randomized in the trial and 234 (167 sibling pairs and 67 parents/siblings) completed the dietary intervention and required DNA blood sampling for genetic analysis. The trial used multiple strategies for recruitment. Hand distributed letters and flyers through mass distribution at various churches resulted in the largest number (n = 153, 46%) of African Americans in the trial. Word of mouth accounted for the second largest number (n = 120, 36%) and included prior study participants. These two recruitment sources represented 82% (n = 273) of the total number of individuals randomized in GET READI. The remaining 18% (n = 60) consisted of a combination of sources including printed message on check stubs, newspaper articles, radio and TV appearances, screening events and presentations. Though challenging, the recruitment efforts for GET READI produced a significant number of African American participants despite the inability to complete the trial as planned because of low recruitment yields. Nevertheless, the recruitment process produced substantial numbers that successfully completed all study requirements.

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 1960's 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.

Exercise without weight loss does not reduce C-reactive protein: the INFLAME study.

PURPOSE: Numerous cross-sectional studies have observed an inverse association between C-reactive protein (CRP) and physical activity. Exercise training trials have produced conflicting results, but none of these studies was specifically designed to examine CRP. The objective of the Inflammation and Exercise (INFLAME) study was to examine whether aerobic exercise training without dietary intervention can reduce CRP in individuals with elevated CRP. METHODS: The study was a randomized controlled trial of 162 sedentary men and women with elevated CRP (> or = 2.0 mg·L(-1)). Participants were randomized into a nonexercise control group or an exercise group that trained for 4 months. The primary outcome was change in CRP. RESULTS: The study participants had a mean (SD) age of 49.7 (10.9) yr and a mean body mass index of 31.8 (4.0) kg·m(-2). The median (interquartile range (IQR)) and mean baseline CRP levels were 4.1 (2.5-6.1) and 4.8 (3.4) mg·L(-1), respectively. In the exercise group, median exercise compliance was 99.9%. There were no differences in median (IQR) change in CRP between the control and exercise groups (0.0 (-0.5 to 0.9) vs 0.0 (-0.8 to 0.7) mg·L(-1), P = 0.4). The mean (95% confidence interval) change in CRP adjusted for gender and baseline weight was similar in the control and exercise groups, with no significant difference between groups (0.5 (-0.4 to 1.3) vs 0.4 (-0.5 to 1.2) mg·L(-1), P = 0.9). Change in weight was correlated with change in CRP. CONCLUSIONS: Exercise training without weight loss is not associated with a reduction in CRP.

Inflammation and exercise (INFLAME): study rationale, design, and methods.

PURPOSE: The INFLAME study is designed to determine the effect of exercise training on elevated high-sensitivity C-Reactive Protein (CRP) concentrations in initially sedentary women and men. METHODS: INFLAME will recruit 170 healthy, sedentary women and men with elevated CRP (>or=2.0 mg/L) to be randomized to either an exercise group or non-exercise control group. Exercising individuals will participate in four months of supervised aerobic exercise with a total energy expenditure of 16 kcal kg(-1) week(-1) (KKW). Exercise intensity will be 60-80% of maximal oxygen consumption (VO(2) max). OUTCOME: The primary outcome will be changed in plasma CRP concentration. Secondary outcomes include visceral adiposity, the cytokines IL-6 and TNF-alpha, and heart rate variability (HRV) in order to examine potential biological mechanisms whereby exercise might affect CRP concentrations. SUMMARY: INFLAME will help us understand the effects of moderate-to-vigorous exercise on CRP concentrations in sedentary individuals. To our knowledge this will be the largest training study specifically designed to examine the effect of exercise on CRP concentrations. This study has the potential to influence therapeutic applications since CRP measurement is becoming an important clinical measurement in Coronary Heart Disease risk assessment. This study will also contribute to the limited body of literature examining the effect of exercise on the variables of visceral adiposity, cytokines, and heart rate variability.