Exercise above Critical Power Elicits Greater Post-Exercise Hypotension than Heavy Exercise Performed to Task Failure

Background: We have previously shown that critical power (CP) is a key threshold determining the magnitude of post-exercise hypotension (PEH), however, whether this finding depended upon 1) the attainment of task failure or 2) could be augmented by increasing exercise duration above CP remained unclear. Purpose: To determine 1) whether a similar magnitude of PEH would occur following exhaustive heavy versus supra-CP exercise, and 2) whether the magnitude of PEH depended upon exercise duration above CP. Methods: Eighteen healthy participants (14 males and 4 females) performed three criterion trials involving exercise performed to task failure at power outputs that elicited exhaustion in either 6 minutes ( WR 6 ), 12 minutes ( WR 12 ), or at a heavy intensity (50%ΔGET-CP, halfway between the gas exchange threshold and CP) and all were followed by 60 minutes of seated recovery. Results: Although time to exhaustion was greatest in 50%ΔGET-CP (2606 ± 732 s) versus WR 12 (790 ± 67 s) and WR 6 (397 ± 42 s, P < 0.001), the magnitude of PEH, as indicated by the change in mean arterial blood pressure (MAP) from baseline ( WR 6 vs 50%ΔGET-CP: -12.9 ± 3.3 mmHg vs -9.4 ± 3.6 mmHg; WR 12 vs 50%ΔGET-CP: -12.8 ± 3.7 mmHg vs -9.4 ± 3.6 mmHg, main effect P <0.01) was greater in WR 6 and WR 12 than 50%ΔGET-CP (all P <0.05). However, the changes in MAP were not different between WR 6 and WR 12 ( P =0.90). Conclusions: These findings reinforce the notion that critical power is a key threshold determining the magnitude of PEH. Specifically, the magnitude of PEH following exhaustive supra-CP exercise remained greater than heavy exercise when the heavy bout was performed to task failure.