Abstract
Assessment of breath acetone level may be an alternative procedure to evaluate change in fat metabolism. The purpose of the present study was to investigate the effect of insufficient carbohydrate (CHO) intake after sprint exercise on breath acetone level during post-exercise. Nine subjects conducted two trials, consisting of either reduced CHO trial (LOW trial) or normal CHO trial (NOR trial). In each trial, subjects visited to laboratory at 7:30 following an overnight fast to assess baseline breath acetone level. They commenced repeated sprint exercise from 17:00. After exercise, isoenergetic meals with different doses of CHO (LOW trial; 18% for CHO, 27% for protein, 55% for fat, NOR trial; 58% for CHO, 14% for protein, 28% for fat) were served. Breath acetone level was also monitored immediately before and after exercise, 1 h, 3 h, 4 h, and 15 h (on the following morning) after completing exercise. A significant higher breath acetone level was observed in LOW trial than in NOR trial 4 h after completion of exercise (NOR trial; 0.66 ppm, LOW trial; 0.9 ppm). However, breath acetone level did not differ on the following morning between two trials. Therefore, CHO intake following an exhaustive exercise affects breath acetone level during early phase of post-exercise.
Highlights
Muscle glycogen content has been recognized to be one of critical factors for determining endurance exercise performance [1,2,3,4]
Trial showed significantly following normal CHO intake after the sprint exercise (NOR trial) markedly decreased higher breath acetone level compared with NOR trial 4 h after completing the exercise
These findings indicate that breath acetone was strongly affected by CHO intake during higher breath acetone level compared with NOR trial 4 h after completing the exercise
Summary
Muscle glycogen content has been recognized to be one of critical factors for determining endurance exercise performance [1,2,3,4]. Betts et al [6] revealed that recovery of muscle glycogen content following an exercise session was accelerated by an adequate quantity (~1 g/body mass/h) carbohydrate CHO intake. Insufficient CHO intake following an endurance exercise session delayed recovery of muscle glycogen content, while low CHO intake facilitated fat metabolism (e.g., increased plasma-free fatty acid concentration and decreased respiratory exchange ratio) compared with high CHO intake [4,7,8]. Augmented fat metabolism during post-exercise period by insufficient CHO intake would reflect delayed recovery of muscle glycogen content. It may be associated with impaired endurance exercise performance during subsequent exercise. Assessment of fat metabolism during the early phase of post-exercise period is valuable
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