Changes in blood volume and oxygenation level in a working muscle during a crank cycle.
OBJECTIVE
This study examined circulatory and metabolic changes in a working muscle during a crank cycle in a pedaling exercise with near-infrared spectroscopy (NIRS).


METHODS
NIRS measurements sampled under stable metabolic and cadence conditions during incremental pedaling exercise were reordered according to the crank angles whose signals were obtained in eight male subjects.


RESULTS
The reordered changes in muscle blood volume during a crank cycle demonstrated a pattern change that corresponded to changes in pedal force and electrical muscle activity for pedal thrust. The top and bottom peaks for muscle blood volume change at work intensities of 180 W and 220 W always preceded (88 +/- 32 and 92 +/- 23 ms, respectively) those for muscle oxygenation changes. Significant differences in the level of NIRS parameters (muscle blood volume and oxygenation level) among work intensities were noted with a common shape in curve changes related to pedal force. In addition, a temporary increase in muscle blood volume following a pedal thrust was detected at work intensities higher than moderate. This temporary increase in muscle blood volume might reflect muscle blood flow restriction caused by pedal thrusts.


CONCLUSIONS
The results suggest that circulatory and metabolic conditions of a working muscle can be easily affected during pedaling exercise by work intensity. The present method, reordering of NIRS parameters against crank angle, serves as a useful measure in providing additional findings of circulatory dynamics and metabolic changes in a working muscle during pedaling exercise.
Takaishi
Tetsuo
T
Institute of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan. takaishi@nsc.nagoya-cu.ac.jp
Sugiura
Takahiro
T
Katayama
Keisho
K
Sato
Yasutake
Y
Shima
Norihiro
N
Yamamoto
Takashi
T
Moritani
Toshio
T
D000328:Adult; D001696:Biomechanical Phenomena; D001810:Blood Volume; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D012039:Regional Blood Flow; D019265:Spectroscopy, Near-Infrared
D010100:Oxygen