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.