Parasympathetic reactivation after maximal CPET depends on exercise modality and resting vagal activity in healthy men

PURPOSE: The main purpose of this study was to investigate parasympathetic reactivation of the heart [evaluated through heart rate recovery (HRR) and HR variability (HRV)] after maximal cardiopulmonary exercise testing (CPET) using three different exercise modalities. METHODS: Twenty healthy men, aged 17 to 28 yr, performed three maximal CPETs (cycling, walking, and running) separated by 72 h and in a randomized, counter-balanced order. HRR was determined from the absolute differences between HR(peak) and HR at 1–3 min after exercise. The root mean square of successive R-R differences calculated for consecutive 30-s windows (rMSSD(30s)) was calculated to assess the parasympathetic reactivation after maximal CPET. RESULTS: Lower HR(peak), VO(2peak) and energy expenditure were observed after the cycling CPET than the walking and running CPETs (P < 0.001). Both HRR and rMSSD(30s) were significantly greater during recovery from the cycling CPET compared to the walking and running CPETs (P < 0.001). Furthermore, Δ rMSSD (i.e. resting minus postexercise rMSSD every 30 s into the recovery period) was positively related to the resting high-frequency component (HF), rMSSD, and standard deviation of all normal R-R intervals (SDNN) (r(s) = 0.89 to 0.98; P < 0.001), and negatively related to the resting low-frequency component (LF) and sympathovagal balance (LF:HF ratio) after all exercise conditions (r(s) = −0.73 to −0.79 and −0.86 to −0.90, respectively; P < 0.001). CONCLUSIONS: These findings support that parasympathetic reactivation after maximal CPET (as assessed by HRR and rMSSD(30s)) depends on exercise modality and cardiac autonomic control at rest.