Effect of Blood Volume in Resting Muscle on Heart Rate Upward Drift during Moderately Prolonged Exercise

Abstract

The aim of this study was to determine whether the increase in blood volume in resting muscle during moderately prolonged exercise is related to heart rate (HR) upward drift. Eight healthy men completed both arm-cranking moderately prolonged exercise (APE) and leg-pedaling moderately prolonged exercise (LPE) for 30 min. Exercise intensity was 120 bpm of HR that was determined by ramp incremental exercise. During both APE and LPE, HR significantly increased from 3 to 30 min (from 108Ϯ9.3 to 119Ϯ12 bpm and from 112Ϯ8.9 to 122Ϯ11 bpm, respectively). However, there was no significant difference between HR in APE and that in LPE. Oxygen uptake was maintained throughout the two exercises. Skin blood flow, deep temperature, and total Hb (blood volume) in resting muscle continuously increased for 30 min of exercise during both APE and LPE. During both APE and LPE, there was a significant positive correlation between total Hb and deep temperature in all subjects. Moreover, there was a significant positive correlation between HR and total Hb (in seven out of eight subjects) during LPE. However, during APE, there was no positive correlation between HR and total Hb (rϭ0.391). These findings suggest that an increase of blood pooling in resting muscle could be proposed as one of the mechanisms underlying HR upward drift during moderately prolonged exercise.

Recommendations for Aerobic Endurance Training Based on Subjective Ratings of Perceived Exertion in Healthy Seniors

“…This upward HR drift decreases stroke volume so that cardiac output can be maintained. It has also been suggested that increased blood pooling in resting muscle accounts for the underlying upward HR drift during moderately prolonged exercise (Kimura, Matsuura, Arimitsu, Yunoki, & Yano, 2010). In contrast, VO 2 did not drift during the entire 2-km walking test.…”