Introduction: Type 2 diabetes is associated with elevated C-reactive protein levels (CRP), which is an independent risk factor for cardiovascular disease. Aerobic exercise training especially with weight/adiposity reduction has been shown to improve CRP, however few studies have evaluated the effect of other exercise training modalities (aerobic, resistance or combination training) on CRP in individuals with type 2 diabetes. Hypothesis: We hypothesize that combination training will improve CRP to a greater extent than other modalities of exercise training, and change in CRP levels will be associated with changes in weight and adiposity. Methods: The present study is a secondary analysis of the Health Benefits of Aerobic and Resistance Training in Individuals with Type 2 Diabetes (HART-D) study. Participants (n=204) were randomized to aerobic exercise (aerobic), resistance exercise (resistance) or a combination of both (combination) for nine months. Results: Baseline CRP was correlated with fat mass, waist circumference, BMI, and inversely correlated with VO2 peak (p<0.05). CRP was not reduced in the 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) groups compared to control (0.35 mg•L-1, 95% CI: -1.0, 1.7). Change in CRP was associated with 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), but not change in fitness or weight (p > 0.05). Conclusions: In conclusion, 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.
PURPOSE: Exercise training has known cardiovascular benefits, however little data exists on the potential additive effects of exercise training combined with increasing non-exercise physical activity on cardiometabolic risk factors, especially in a long duration intervention. METHODS: We randomized obese adults (N=45) to one of 3 groups: 1) aerobic training (AERO); 2) aerobic training and increasing non-exercise physical activity (AERO-PA) or; 3) a control group for 6 months. Both the AERO and AERO-PA groups participated in aerobic training at 50-75% VO2 max at a dose of 12 kcals/kg/week. In addition to exercise training, the AERO-PA group participated in behavioral coaching sessions to determine strategies to increase non-exercise physical activity levels (measured via accelerometer) by 3,000 steps/day. The main outcome of the trial was waist circumference. Secondary outcomes included fitness (VO2 max), body composition (dual-energy X-ray absorptiometry), and insulin action (oral glucose tolerance test). RESULTS: The study population had a mean (SD) age of 52.6 (7.6) yrs., body mass index of 36.0 kg/m2 (4.8) and a physical activity level of 4635.6 (1242.7) steps/day at baseline. A significant higher steps/day was observed in the AERO-PA group (7216.6) compared to the AERO (5662.3, p=0.007) or CON (5330.3, p=0.029). Intent to treat analyses revealed significant changes in absolute VO2 max (0.28 vs. 0.09 L/min), relative VO2 max (3.8 vs. 0.91 ml.kg.min) and estimated maximal METs (Est METs) (1.2 vs. 0.52 METs) in the AERO-PA compared to the AERO group (all p<0.05). No effects were observed for waist circumference, body mass, body composition, or insulin action variables. Person correlations showed that change in steps during the intervention in exercisers were associated with improvements in Est METs (r=0.54, p=0.007), body weight (r= -0.43, p=0.03), waist circumference (r=-0.54, p=0.005) and approached significance for body fat (r=-0.40, p=0.054). CONCLUSIONS: Exercise training and increasing non-exercise physical activity resulted in a greater improvement in fitness compared to aerobic training alone (Δ0.71 METs), which may be clinically important based on epidemiological data. In addition, higher step levels outside of exercise are supportive for improvements in body composition.
Introduction: Current calculators to estimate risk of cardiovascular (CV) disease mortality do not include cardiorespiratory fitness (CRF) or physical activity (PA) measures. This is problematic as CRF is an independent risk factor for CV mortality. To address this issue, Wickramasinghe et al. developed a calculator which includes CRF along with other traditional CV risk factors. The purpose of the present study is to determine the effect of aerobic (AER), resistance (RES) or combination (COMB) exercise training on 30-year CV mortality risk in individuals with type 2 diabetes (T2D). Methods: The present study is an ancillary analysis of the Health Benefits of Aerobic and Resistance Training Study (HART-D). Adults with type 2 diabetes (T2D) (n=196) were randomized to 9 months of AER, RES, COMB exercise training or a control group (CON). Thirty-year CV mortality risk was evaluated by entering each participant’s sex, age, blood pressure, smoking status, T2D status, cholesterol, and BMI into a risk calculator developed by Wickramasinghe et al. at baseline and follow-up. CRF was quantified as the highest metabolic equivalent level (estimated from the final speed and grade using American College of Sports Medicine equations) achieved during a maximal treadmill test at baseline and follow-up. Analysis of covariance was used to evaluate change in CV risk with adjustments for age, sex and baseline CV risk. Results: Participants in the present analysis had a mean (SD) 30-year CV risk of 30.4% (17.8). A significant reduction in 30-year CV risk was observed in the AERO (-2.9%, CI: -4.7 to -1.0) and COMB groups (-2.8%, CI: -4.5 to -1.0), but not in the RES group (0.0%, CI: -1.8 to 1.7) compared to CON (2.1%, CI: -0.1 to 4.3). In the AERO and COMB groups, change in CV risk was associated with change in fat mass (r= -0.19, p=0.04), but not change in lean mass or hemoglobin A1c (all ps>0.05). Conclusions: The present study suggests that 9 months of aerobic exercise training or combination of resistance with aerobic exercise training resulted in a ~3% reduction in absolute 30-year CV risk (~11% relative risk), and further validates the importance of aerobic exercise in the treatment of individuals with T2D.
This is data from a published paper evaluating the impact of weight loss combined with exercise training on cardiometabolic risk factors (e.g. insulin resistance, body composition, fitness, lipids). The final paper is published in Plos ONE (Title:Effects of aerobic training with and without weight loss on insulin sensitivity and lipids)
PURPOSE: To illustrate the connection between lipoprotein-insulin resistance index (LPIR) scores and a combined weight loss and aerobic exercise intervention. METHODS: Thirty sedentary overweight and obese adults (Age: 46.2 ± 10.7 yrs.; Weight: 95.4 ± 12.6 kg; BMI: 34.4 ± 3.3 kg/m2) completed a 10-week OPTIFAST weight loss program and supervised aerobic exercise training program to achieve clinical weight loss (≥7% body weight). The OPTIFAST program involved consuming meal-replacement products totaling ~800 kcals per day and weekly classes on behavior modification and nutrition. The weekly aerobic exercise volume was 300 MET min and increased by 50 MET min each week until 700 MET min per week was reached. Plasma blood samples were analyzed via nuclear magnetic resonance (NMR) spectroscopy (LabCorp, Burlington, NC) at baseline and follow-up, and LPIR score was calculated through the summation of selected lipoprotein parameters and then scaled 0-100 (most to least insulin sensitive). RESULTS: Participants had significant reductions in weight (9.9%) (-8.4, CI [-9.5, -7.4] kg), % fat mass (-2.1, CI [-2.7, -1.4] %), and waist circumference (-7.7, CI [-9.3, -6.2] cm), but no change in peak oxygen uptake (0.02, CI [-0.03, 0.1] L/min) was observed after the intervention. Additionally, there were significant reductions in LPIR score (-12.1, CI [-17.1, -7.1]), insulin (-8.9, CI [-14.3, -3.7] uIU/mL), and glucose (-11.2, CI [-13.9, -8.5] mg/dL), along with significant decreases in blood lipid levels: triglycerides (-27.2, CI [-42.8, -11.6] mg/dL), and lipoproteins: very-low-density lipoprotein (-5.5, CI [-8.7, -2.4] mg/dL) and low-density lipoprotein (-7.9, CI [-14.1, -1.8] mg/dL). Changes in LPIR were associated with changes in triglycerides (r = 0.41, p = 0.025). No significant associations were observed between changes in LPIR and body composition, fitness, or blood pressure changes (p > 0.05). CONCLUSIONS: LPIR improved following an OPTIFAST program with aerobic exercise, suggesting a reduction in T2DM risk independent of traditional glycemic measures. Future research should investigate how to maintain improvements in LPIR during weight maintenance.
Abstract 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.
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 with a lower dose.The primary aim of our current report was to examine whether exercise dose affects bilirubin levels in obese postmenopausal women from the Dose-Response to Exercise in Women 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 to 4, 8, and 12 kcal·kg⁻¹·wk⁻¹ (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⁻¹, P = 0.026) compared with the control group (0.004 mg·dL⁻¹). Subgroup analyses showed that there was a significant increase in bilirubin levels in participants in the 12-KKW group (0.076 mg·dL⁻¹) who were classified as insulin resistant (homeostatic model assessment for insulin resistance score > 2.6) compared with insulin-resistant control participants (0.018 mg·dL⁻¹, P = 0.028).Our findings suggest that high doses of exercise training are necessary to significantly increase bilirubin levels in previously sedentary postmenopausal women and especially those with impaired glucose metabolism.
