title: Muscle pump in the vastus lateralis in the supine position in light prolonged exercise.
abstract: OBJECTIVE
  The purpose of this study was to examine whether the muscle pump in the supine position is attenuated during light prolonged exercise.
  
  
  METHODS
  After rest for 5 min, constant-load exercise with 50% of peak oxygen uptake (VO2) determined by incremental exercises in the supine position was performed for 60 min with a pedaling rate of 60 rpm. Total hemoglobin and myoglobin (total Hb) in the vastus lateralis was determined by using a near-infrared spectroscopy (NIRS) system. The instrument was operating at 2 Hz. VO2, heart rate (HR), mean blood pressure (MBP) and muscle deep temperature (Tm) were measured in the constant-load exercise.
  
  
  RESULTS
  After an increase at the onset of exercise, VO2 showed a steady state, HR showed a significant gradual increase and MBP significantly decreased. After an increase until 20 min of exercise, Tm showed a steady state. Level of total Hb increased until 20 min and showed a steady state in all subjects. Average Tm was significantly related to average total Hb (r=0.978). Total Hb oscillated, but its oscillation occasionally disappeared. Peak amplitude of oscillation in total Hb for 30 s after the start of exercise was significantly higher than that for 1 min before the end of exercise.
  
  
  CONCLUSIONS
  The results suggest that the muscle pump operates in light exercise but is attenuated in the vastus lateralis in the supine position at the late phase of prolonged exercise.
authors.affiliation: Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Sapporo, Japan - yano@edu.hokudai.ac.jp.
authors.forename: T
authors.initials: T
authors.lastname: Yano
authors.forename: C S
authors.initials: CS
authors.lastname: Lian
authors.forename: R
authors.initials: R
authors.lastname: Afroundeh
authors.forename: K
authors.initials: K
authors.lastname: Shirakawa
authors.forename: T
authors.initials: T
authors.lastname: Yunoki
mesh_terms: D001794:Blood Pressure; D005080:Exercise Test; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009211:Myoglobin / Q000378:metabolism; D010807:Physical Endurance; D005082:Physical Exertion; D052097:Quadriceps Muscle / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared; D016683:Supine Position; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D009211:Myoglobin