Is the magnitude of acute post-exercise hypotension mediated by exercise intensity or total work done?

Abstract

The purpose of this study was to investigate the effects of exercise intensity on the magnitude of acute post-exercise hypotension while controlling for total work done over the exercise bout. Seven normotensive physically active males aged 28 ± 6 years (mean ± SD) completed four experimental trials, a no exercise control, 30 min of semi-recumbent cycling at 70% $\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2{\text{peak}}}}$ (INT), cycling for 30 min at 40% $\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2{\text{peak}}}}$ (SMOD) and cycling at 40% $\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2{\text{peak}}}}$ for a time which corresponded to the same total work done as in the intense trial (LMOD). Blood pressure (BP), heart rate, stroke volume, cardiac output, total peripheral resistance, core body temperature and forearm skin and limb blood flow were measured prior to and for 20 min following the exercise bout. Post-exercise summary statistics were compared between trials with a one-factor general linear model. The change in systolic BP, averaged over the 20-min post-exercise period was significantly lower only following the INT (−5 ± 3 mm Hg) and LMOD exercise (−1 ± 7 mm Hg) compared to values in control (P < 0.04). The changes in systolic BP and MAP following INT and LMOD were not significantly different from each other (P > 0.05). Similar results were obtained when the minimum values of these variables recorded during the post-exercise period were compared. Mean changes in cardiac output (1.9 ± 0.3 l min⁻¹) and total peripheral resistance (−3 ± 1 mm Hg l⁻¹ min⁻¹) after INT exercise were also different from those in CON (P < 0.0005). The acute post-exercise reduction in BP was clinically similar following high intensity short duration exercise and moderate intensity longer duration exercise that was matched for total work done.