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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
EXCERCISE PHYSIOLOGY AND BIOMECHANICS
Yano T., Lian C-S., Afroundeh R., Shirakawa K., Yunoki T.
Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Sapporo, Japan
AIM: 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.
CONCLUSION: 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.