title: 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 108±9.3 to 119±12 bpm and from 112±8.9 to 122±11 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 (r=0.391). 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.
authors.affiliation: Laboratory of Exercise Physiology, Graduate School of Education, Hokkaido University, Sapporo, Japan. ptswimmer@triton.ocn.ne.jp
authors.forename: Takehide
authors.initials: T
authors.lastname: Kimura
authors.forename: Ryouta
authors.initials: R
authors.lastname: Matsuura
authors.forename: Takuma
authors.initials: T
authors.lastname: Arimitsu
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yunoki
authors.forename: Tokuo
authors.initials: T
authors.lastname: Yano
mesh_terms: D000704:Analysis of Variance; D001810:Blood Volume / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D012867:Skin / Q000098:blood supply; D013696:Temperature; D055815:Young Adult
chemical_list: D006454:Hemoglobins