Postexercise heart rate variability following treadmill and cycle exercise: a comparison study.

The purpose of this study was to compare postexercise heart rate variability (HRV) immediately following acute bouts of treadmill (T) and cycle (C) exercise at 65% of mode-specific maximal oxygen consumption reserve (65% VO2 R). Fourteen apparently healthy men participated in this study. On two separate and randomized days, each participant performed 30 min of exercise at 65% VO2 R on T and C. Supine HRV was evaluated as normalized and log-transformed (ln) high-frequency (HF) and low-frequency (LF) spectral power, as well as the LF:HF ratio in 5-min segments immediately before (PRE) and at 10-15 min (POST1) and 25-30 min (POST2) following each exercise bout. There were no significant differences in the HRV values at PRE between the modalities. Following each exercise bout, lnHF was significantly lower at POST2 following C compared to T. In addition, lnLF and LF:HF were significantly higher at POST1 and POST2 following C compared to T. All HRV metrics returned towards baseline 30 min following T but remained significantly different than PRE values after C. These results suggest that following exercise at 65% of mode-specific VO2 R, C is associated with a greater delay of postexercise HRV recovery than T in apparently healthy men.