Cumulative Effects Of Training At Different Weekly Energy Expenditures On Cardiorespiratory Fitness And Obesity

BACKGROUND: Current evidence points to overall exercise volume as a primary driver of body composition improvements; similar improvements in cardiorespiratory fitness (CRF) and obesity occur when equivalent exercise volumes are accumulated in varying bout lengths. PURPOSE: To determine the cumulative effects of vigorous intensity training at different weekly exercise energy expenditures (ExEE) but similar total overall volume on CRF and obesity. METHODS: Following completion of the initial 9-mo STRRIDE trial, 22 participants underwent an additional 6-mo of exercise training in one of two groups: 1) Low Amount Vigorous Intensity (LV; n = 14): 14 kcal ExEE/kg/week (KKW) at 65-80% peak VO2; 2) High Amount Vigorous Intensity (HV; n = 8): 23 KKW at 65-80% peak VO2. Assessments included relative peak VO2 via gas exchange during graded maximal exercise testing, body mass, and minimal waist circumference. Comparisons between groups were performed via t-tests (α = 0.05) at equivalent time points and time points of nearly equivalent cumulative ExEE (LV at 15 mo vs HV at 9 mo). RESULTS: As shown in Figure 1, after training, the mean changes from baseline to 9 mo and 15 mo, respectively, were peak VO2 : 16.2% ± 12.2 to 22.4% ± 16.2 for HV and 9.4% ± 8.1 to 13.8% ± 9.8 for LV; body mass: -2.6% ± 3.2 to -4.8% ± 5.9 for HV and -1.7% ± 4.0 to -3.4% ± 3.9 for LV; and waist circumference: -1.9% ± 2.8 to -2.9% ± 4.5 for HV and -1.8% ± 3.7 to -3.6% ± 4.1 for LV. At equivalent time points, magnitudes of change in these outcomes were not significantly different between groups. For cumulative ExEE comparisons, magnitudes of change for all outcomes in the LV group at 15-mo were not significantly different from the HV group at 9-mo. CONCLUSION: When cumulative ExEE was nearly equivalent, we did not detect a difference between the effects of lower weekly volumes of vigorous intensity exercise over a prolonged period and those of higher weekly volumes at a similar intensity over a shorter period on markers of CRF and obesity.STRRIDE I funding: HL057354; AHA funding: 23CDA1051777