Influence of cool-down exercise on autonomic control of heart rate during recovery from dynamic exercise.
The recovery of post-exercise heart rate (HR) is enhanced by a procedure of cooling down; however, the mechanism of this facilitated reduction is unknown. To determine whether more cardiac vagal reactivation is associated with a decrease in HR following cool-down exercise, we examined high-frequency R-R interval variability (HF, 0.15-0.40 Hz), an index of cardiac vagal tone, in six young healthy male subjects with a comparison between sitting rest after 6 minutes of cool-down cycling at 20% peak oxygen uptake (VO2peak) and sitting complete rest, following 5 min of upright cycle exercise at 70% VO2peak. During the last minute of exercise, there was no difference in HR between the two exercise tests before performing or not performing cool-down exercise (mean +/- SE, 148.7 +/- 6.9 versus 149.7 +/- 7.0 beats/min, respectively, by a Wilcoxon signed-ranks test). After exercise, a similar initial rapid decrease in HR and subsequent decline was observed during the first 6 min of recovery, regardless of cool-down exercise. However, the resting HR average following cool-down exercise was significantly lower than the corresponding HR without cool-down exercise (92.1 +/- 3.0 versus 100.8 +/- 3.6 beats/min, P < 0.05). The corresponding HF amplitude was slightly, but significantly greater with than without cool-down exercise (10.6 +/- 2.2 versus 9.0 +/- 1.9, P < 0.05). Thus the increase in HF amplitude corresponded to a decrease in resting HR following cool-down exercise, as compared to complete rest without cool-down exercise. Therefore, we conclude that after moderate exercise, the decrease in resting HR following cool-down exercise is associated with an increase in cardiac vagal tone.
Takahashi
Tatsuhisa
T
Department of Biomedical Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Joh-nan, Yonezawa 992-8510, Japan. takahasi@eie.yz.yamagata-u.ac.jp
Okada
Akiyoshi
A
Hayano
Junichiro
J
Tamura
Toshiyo
T
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology; D002302:Cardiac Output; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005221:Fatigue; D006321:Heart / Q000294:innervation / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D012146:Rest / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology