Muscle Oxygen Saturation Heterogeneity Among Leg Muscles During Ramp Exercise
We examined whether O2 saturation in several leg muscles changes as exercise intensity increases. Twelve healthy young males performed 20 W/min ramp bicycle exercise until exhaustion. Pulmonary O2 uptake (VO2) was monitored continuously during the experiments to determine peak oxygen uptake. Muscle O2 saturation (SmO2) was also monitored continuously at the belly of the vastus lateralis (VL), rectus femoris, vastus medialis, biceps femoris, gastrocnemius lateralis, gastrocnemius medialis, and tibialis anterior by near-infrared spatial resolved spectroscopy. Although the VL muscle mainly contributes during cycling exercise, deoxygenation was enhanced not only in the VL muscle but also in the other thigh muscles and lower leg muscles with increased exercise intensity. Furthermore, SmO2 response during ramp cycling exercise differed considerably between leg muscles.
KeywordsMuscle oxygen saturation Heterogeneity Oxygen uptake Cycling exercise Near-infrared spatial resolved spectroscopy
The authors are grateful for revision of this manuscript by Andrea Hope. We also thank Mikiko Yonemitsu and Ayaka Kime for their helpful technical assistance. This study was supported in part by Grant-in-Aid for Young Scientists from the Japan Society for Promotion of Science 22700702 to R. Kime.
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