Affiliations: [a] Institute of Health Science and Applied Physiology,
Kinki Welfare University, Hyogo, Japan | [b] Graduate School of Sport Sciences, Osaka University of
Health and Sport Sciences, Osaka, Japan | [c] Institute for Higher Education Research and Practice,
Osaka University, Osaka, Japan | [d] Graduate School of Human Sciences, Osaka University,
Osaka, Japan
Note: [] Address for correspondence: Takanobu Okamoto, Institute of
Health Science and Applied Physiology, Kinki Welfare University, 1966-5,
Takaoka, Fukusaki, Kanzaki, Hyogo, 679-2217 Japan. Tel.: +81 790 22 2620; Fax:
+81 790 23 0662; E-mail: [email protected]
Abstract: The aims of the present study were to clarify the differences in
muscle oxygen dynamics between eccentric (ECC) and concentric (CON)
contractions and to investigate the relationship between muscle oxygen dynamics
and the pattern of skeletal muscle recruitment during ECC and CON contractions.
Fifteen healthy male subjects (age 21.8 ± 2 yrs) performed
isokinetic ECC and CON knee extension and flexion exercise for 1 min at an
angular velocity of 180°/s. Changes in muscle
oxygenation (MO) levels in the active muscle were measured using near-infrared
spectroscopy (NIRS) whose probe was placed on the rectus femoris. Bipolar
surface electrodes recorded the electromyogram (EMG) activity of this muscle.
The MO levels during ECC contraction were significantly higher at 10 s and 15 s
after the onset of exercise while MO levels during CON contraction were
significantly higher 60 s following the onset of exercise. A significant
correlation was indicated between MO levels and EMG activity during CON
contraction (p<0.05). These results reveal that oxygen
supply-consumption balance in ECC and CON contraction are different. Moreover,
this suggests that muscle activity in CON contraction increases and the oxygen
supply to active muscle may exceed the oxygen consumption in active muscle.
