EFFECTS OF DIFFERENT WORK INTENSITY ON MUSCLE OXYGEN CONSUMPTION DURING INTERMITTENT EXERCISE

Abstract

384 This study investigated an effect of different work intensity (maximal and VT work intensity) on changes in muscle oxygenation and on muscle oxygen consumption (muscle VO2) during the intermittent exercise. Eight healthy male subjects participated in this study. Determination of the maximal and VT work intensity resulted from incremental exercise test. The intermittent exercise consisted of; Ratio of work and rest periods during the intermittent exercise were 10 sec: 10 sec with 60rpm, total exercise time was 10 min. The changes of oxygenation were measured by near-infrared spectroscopy using continuous wave (NIRcws). In the present study, the changes of oxygenation resulted from the arterial occlusion at every 3rd repetitions of intermittent exercise. Thigh volume and the quadriceps femoris muscle mass were calculated from the formula by Jones and Pearson (1969). Oxygenation of VT work intensity exercise decreased until 50% level during exercise period and recovered from 90% level at rest period. Oxygenation of maximal work intensity exercise decreased until 20% level from resting level exercise period and recovered from 60% level at rest period. Muscle VO2 were 3.7± 0.23%/kg during resting condition, 20.6 ± 2.43%/kg during maximal work intensity and 27.5 ± 2.69%/kg during VT work intensity, respectively. In conclusion, the results obtained suggest that, during intermittent exercise, the maximal work intensity exercise more depend on anaerobic energy supply system than the VT work intensity exercise, considering that the maximal work intensity exercise restarted the exercise under the insufficient oxygenation condition (60%) compared to the VT work intensity exercise with sufficient oxygenation condition (90%).