The Impact of a 12-week High-Intensity Interval Training Program on Sympathetic Transduction in Healthy Adults: A Pilot Project.

Abstract

Peak pressor responses (i.e., sympathetic transduction) following bursts of muscle sympathetic nerve activity (MSNA) are inversely related to peak oxygen consumption (V̇O2peak) in younger males, but not females. However, it is unknown whether high-intensity interval training (HIIT) decreases sympathetic transduction. I tested the hypothesis that 12-weeks of HIIT (n=9) would improve V̇O2peak and attenuate sympathetic transduction versus a Control group (n=5). At baseline and follow-up, V̇O2peak (via graded cycle ergometry), resting peroneal MSNA (via microneurography) and beat-by-beat diastolic blood pressure (DBP; via finger photoplethysmography) were recorded. Peak DBP increases following MSNA bursts quantified sympathetic transduction. Nadir DBP following non-MSNA heartbeats were also determined. HIIT training improved V̇O2peak (P=0.003), with no changes observed in the Control group (P=0.279). Sympathetic transduction did not change in either group (Interaction P=0.647). However, decreases in DBP during sympathetic quiescence were larger following HIIT (P=0.006), but unchanged in the Control group (P=0.638). These results indicate that HIIT-mediated increases in aerobic fitness did not alter sympathetic regulation of DBP but may have enhanced competing local vasodilatory mechanisms.