Clinically significant weight loss is associated with health benefits for overweight and obese adults. Participation in adequate amounts of physical activity is critical for weight maintenance. However, the recommended amount of physical activity needed to promote weight maintenance is based primarily on retrospective studies that quantified physical activity levels through questionnaires which tend to overestimate physical activity levels. In addition, the present literature has provided little data on the impact of these physical activity levels on cardiovascular and diabetes risk factors, which may have equal or more clinical importance than weight changes. The Prescribed Exercise to Reduce Recidivism After Weight Loss-Pilot (PREVAIL-P) study will evaluate the effect of aerobic exercise training amount on weight maintenance following clinically significant weight loss in overweight and obese adults (BMI 25–40 kg/m 2 ) age 30–65 years. Participants (N = 39) will complete a 10-week OPTIFAST® weight loss program with supervised aerobic exercise training. Individuals who achieve ≥7% weight loss from baseline will be subsequently randomized to levels of aerobic training consistent with physical activity recommendations (PA-REC) or weight maintenance recommendations (WM-REC) for 18 additional weeks. The primary outcome of the PREVAIL-P study will be change in weight from the completion of OPTIFAST® program to the end of the study. Notable secondary measures include changes in clinically relevant cardiometabolic risk factors between study groups (e.g. blood lipids concentrations, oral glucose tolerance, arterial stiffness). This pilot study will be used to estimate the effect sizes needed for a randomized controlled trial on this topic.

Background African Americans have a disproportionate prevalence and incidence of type 2 diabetes compared to Caucasians. Recent evidence indicates low cardiorespiratory fitness (CRF) level, an independent risk factor for type 2 diabetes, is also more prevalent in African Americans than Caucasians. Numerous studies in Caucasian populations suggest vigorous exercise intensity may promote greater improvements in CRF and other type 2 diabetes risk factors (e.g. reduction of glucose/insulin levels, pulse wave velocity, body fat, etc.) than moderate intensity. However, current evidence comparing health benefits of different aerobic exercise intensities on type 2 diabetes risk factors in African Americans is negligible. This is clinically important as African Americans have a greater risk for type 2 diabetes and are less likely to meet public health recommendations for physical activity than Caucasians. The purpose of the High-Intensity exercise to Promote Accelerated improvements in CardiorEspiratory fitness (HI-PACE) study is to evaluate whether high-intensity aerobic exercise elicits greater improvements in CRF, insulin action, and arterial stiffness than moderate-intensity exercise in African Americans. Methods/Design­ A randomized controlled trial will be performed on overweight and obese (body mass index: 25-45 kg/m2) African Americans (35-65 years) (n=60). Participants will be randomized to moderate-intensity (MOD-INT) or high-intensity (HIGH-INT) aerobic exercise training, or a non-exercise control group (CON) for 24 weeks. Supervised exercise will be performed at a heart rate associated with 45-55% and 70-80% of VO2 max in the MOD-INT and the HIGH-INT groups, respectively, for an exercise dose of 600 MET-minutes/week (consistent with public health recommendations). The primary outcome is change in CRF. Secondary outcomes include change in insulin sensitivity (measured via an intravenous glucose tolerance test), skeletal muscle mitochondrial oxidative capacity (via near infrared spectroscopy), skeletal muscle measurements (i.e. citrate synthase, COX IV, GLUT-4, CPT-1, PGC1-α), arterial stiffness (via carotid-femoral pulse wave velocity), body fat, C-reactive protein, and psychological outcomes (quality of life/exercise enjoyment). Discussion The anticipated results of the HI-PACE study will provide vital information on the health effects of high-intensity exercise in African Americans. This study will advance health disparity research and has the potential to influence future public health guidelines for physical activity. Trial Registration ClinicalTrials.gov ID: NCT02892331. Registered on 8 September 2016, https://clinicaltrials.gov/ct2/show/NCT02892331

Background African Americans have a disproportionate prevalence and incidence of type 2 diabetes compared to Caucasians. Recent evidence indicates low cardiorespiratory fitness (CRF) level, an independent risk factor for type 2 diabetes, is also more prevalent in African Americans than Caucasians. Numerous studies in Caucasian populations suggest vigorous exercise intensity may promote greater improvements in CRF and other type 2 diabetes risk factors (e.g. reduction of glucose/insulin levels, pulse wave velocity, body fat, etc.) than moderate intensity. However, current evidence comparing health benefits of different aerobic exercise intensities on type 2 diabetes risk factors in African Americans is negligible. This is clinically important as African Americans have a greater risk for type 2 diabetes and are less likely to meet public health recommendations for physical activity than Caucasians. The purpose of the High-Intensity exercise to Promote Accelerated improvements in CardiorEspiratory fitness (HI-PACE) study is to evaluate whether high-intensity aerobic exercise elicits greater improvements in CRF, insulin action, and arterial stiffness than moderate-intensity exercise in African Americans. Methods/Design­ A randomized controlled trial will be performed on overweight and obese (body mass index: 25-45 kg/m2) African Americans (35-65 years) (n=60). Participants will be randomized to moderate-intensity (MOD-INT) or high-intensity (HIGH-INT) aerobic exercise training, or a non-exercise control group (CON) for 24 weeks. Supervised exercise will be performed at a heart rate associated with 45-55% and 70-80% of VO2 max in the MOD-INT and the HIGH-INT groups, respectively, for an exercise dose of 600 MET-minutes/week (consistent with public health recommendations). The primary outcome is change in CRF. Secondary outcomes include change in insulin sensitivity (measured via an intravenous glucose tolerance test), skeletal muscle mitochondrial oxidative capacity (via near infrared spectroscopy), skeletal muscle measurements (i.e. citrate synthase, COX IV, GLUT-4, CPT-1, PGC1-α), arterial stiffness (via carotid-femoral pulse wave velocity), body fat, C-reactive protein, and psychological outcomes (quality of life/exercise enjoyment). Discussion The anticipated results of the HI-PACE study will provide vital information on the health effects of high-intensity exercise in African Americans. This study will advance health disparity research and has the potential to influence future public health guidelines for physical activity.

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Objective: The OPTIFAST diet has known effects for weight loss, but little data exists on the effects of the diet on arterial stiffness. Methods: Overweight and obese (BMI: 34.5 + 4.0) adults (N=17) participated in a 10-week OPTIFAST™ weight loss program and supervised aerobic exercise training (50%-75% VO 2 max). The diet consisted of OPTIFAST meal replacement products with a goal of reducing total caloric intake to 800 kcals/day and attending a weekly weight management class. Aerobic exercise was performed 3 times per week and the exercise volume was progressed from 300 to 700 MET mins. per week at an intensity of 50%-75% VO2 max. The goal of study participants was to achieve a 7% weight loss. Carotid-to-femoral pulse wave velocity, blood pressure (aortic and brachial), vascular age, augmentation index and blood samples were measured in the morning after an overnight fast at baseline and follow-up. A paired t-test was performed to evaluate the change in outcomes variables. Results: The mean percent weight loss in the sample was 9.0% (-8.5 kg), with 83.3% of participants achieving 7% weight loss (94.1% achieving ≥5%). The adherence to the exercise program was 94.9% and attendance in the weight loss classes was 81.8%. There was a reduction in pulse wave velocity (-0.44 m/s, p=0.030), aortic systolic blood pressure (-10.5 mmHg, p<0.001), aortic diastolic blood pressure (-7.8 mmHg, p<0.001), brachial systolic blood pressure (-11.2 mmHg , p<0.001), brachial diastolic blood pressure (-7.7 mmHg, p<0.001), vascular age (-13.4 yrs., p=0.008), resting heart rate (-4.7 bpm, p=0.005), and augmentation index (-7.5%, p=0.008) after the intervention. Change in resting heart rate from the intervention was associated with improvements in augmentation index (r=0.60, p=0.010) and approached significance for pulse wave velocity (r=0.45, p=0.07). Weight loss was associated with reduction in augmentation index (r= 0.56, p=0.02), but not change in PWV (r=-0.07, p=0.78). Changes in other cardiometabolic risk factors (e.g. glucose, insulin, lipids, and body fat) were not associated with improvements in arterial stiffness or blood pressure measures (all ps>0.05). Discussion: A hypo-caloric dietary program in combination with aerobic exercise training improves arterial stiffness, aortic blood pressure, and brachial blood pressure in overweight and obese adults An important limitation of the present study is that we cannot separate the health benefits of the diet from the exercise.