Muscle oxygen consumption at onset of exercise by near infrared spectroscopy in humans.
In this study, we tried to continuously measure muscle oxygen consumption (m-VO2) by near infrared spectroscopy (NIRS) without arterial occlusions. We used an intermittent isometric exercise at high intensity, which elicits a spontaneous occlusion of the blood flow to the muscle due to an increase in intramuscular pressure. Changes in muscle oxygenation and phosphocreatine (PCr) concentration were monitored in 5 subjects during an intermittent isometric exercise (5 sec. contraction/5 sec. relaxation) at 50% of maximum voluntary contraction for 3 minutes. The rate of deoxygenation was measured from the 2nd sec. to the 3rd sec. of each muscle contraction. The rate of deoxygenation at the onset of exercise followed an exponential time course with a time constant of 42.0 +/- 12.5 sec. (mean +/- SD). This value agreed with the time constant of the decrease in PCr (48.2 +/- 10.2 sec.). This result suggests that m-VO2 was successfully monitored with a time resolution of 10 sec. by NIRS during exercise without arterial occlusion.
Hamaoka
Takafumi
T
Department of Preventive Medicine and Public Health, Tokyo Medical University, Japan.
Katsumura
Toshihito
T
Murase
Norio
N
Sako
Takayuki
T
Higuchi
Hiroyuki
H
Murakami
Motohide
M
Esaki
Kazuki
K
Kime
Ryotaro
R
Homma
Toshiyuki
T
Sugeta
Akiko
A
Kurosawa
Yuko
Y
Shimomitsu
Teruichi
T
Chance
Britton
B
D000328:Adult; D015444:Exercise; D006801:Humans; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
D010100:Oxygen