Hiit Training At Ventilatory Threshold And Vo2 Response In Hiv + And Hiv- Women

Training at or above ventilatory threshold (T@VT) could represent the critical intensity needed to stimulate a highest state of oxidative phosphorylation for adaptations in VO2max. In a previous study, we observed that 50% of HIV+ women did not improve VO2max after a 6-week low volume HIIT (non-responders), while 50% of HIV+ and all HIV- improved (responders). PURPOSE: To compare responders and non-responders in: 1) the proportion T@VT, and 2) the oxygen demand at different workloads at pre- and post-testing. METHODS: Using data from our previous study in which maximal exercise test was conducted on a cycle ergometer, we identified responders and non-responders who T@VT using the workload at which VT occurred (average = 86.8 ± 24.9 and 92.7 ± 22.3 W, respectively). Then, we compared VO2max, the percentage of VO2max at each workload increment during the exercise test and at VT to determine mechanical efficiency, and at 3-min recovery. A 2-way ANOVA was used to determine differences between responders and non-responders. RESULTS: 68% (6/9) of responders and 80% (8/10) of non-responders T@VT (Chi2: P = 0.61). Higher VO2max, and lower percent of VO2max at 25 W, 50 W, 75 W, and VT were observed only among responders who T@VT compared with responders who trained below VT (post-test: VO2max = 24.1 ± 3.8 vs 19.5 ± 3.3 ml·kg-1·min-1; %VO2max@25 W = 37.2 ± 8.2 vs 49.7 ± 7.5; %VO2max@50 W = 65.2 ± 11.2 vs 79.4 ± 11.1; %VO2max@75 W = 68.3 ± 12.9 vs 87.3 ± 13.8; %VO2max@100 W = 83.2 ± 12.2 vs 95.9 ± 8.2; %VO2max@VT = 74.8 ± 9.9 vs 82.6 ± 8.2; P < 0.05 for all). Percent of VO2max at 3-min recovery was not different between responders and non-responders who T@VT or below VT. CONCLUSION: While, T@VT did not explain the difference in VO2max improvement after HIIT between responders and non-responders, the effect of T@VT on VO2max and mechanical efficiency could be observed only among responders. NIMHD S21MD001830, R21MH095524, U54MD007587-04, and R25MD007607