The purpose of this study was to examine the effect of altitude training on muscle oxygenation in skeletal muscles during anaerobic maximal exercise. Eight young male and 3 female skiers (15.4+0.2 (SE) years) were exposed to S weeks of physical training, 4-5 hours a day at an elevation of 2,700 m or 3,700 m (for 3 days) in summer. Living quarters were at 2,100 m for 2 weeks and then at 2,700 m for 3 weeks. A near infrared continuous wave spectroscopy (NIRcws) was used for measuring muscle (on right vastus lateralis) oxygenation continuously and noninvasively during a Wingate test as anaerobic maximal exercise below sea level. Subjects performed the Wingate test before and after the training. Muscular power output was calculated by video analysis for S-sec periods. There were no significant differences between the values of peak power and mean power obtained before and after the training. During the Wingate test, blood volume decreased after the onset of exercise compared to resting level within 7-10 sec. However, there was no significant difference between changes in blood volume before and after the training. On the other hand, muscle oxygenation indicated a linear decrease from the onset of exercise to 7 sec, and showed a constant level from 8 sec to 30 sec. The minimum level of muscle oxygenation did not change substantially after the training, while there was a significant difference in regression coefficient of regression slope from the start of exercise to 7 sec (p<0.05). This result suggests that levels of oxygenated hemoglobin and /or myoglobin decreased slowly, indicating that the same value as maximal power with lower oxygen utility was obtained after the training than that obtained before the training. It is thinkable that muscular mechanical efficiency improves due to altitude training. To clarify this finding it is necessary to bserve differences in effects on the oxygenation of skeletal muscles between sea level training and altitude training.
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