Metabolic responses to exercise on land and in water following glucose ingestion

Summary Although aerobic exercise after a meal decreases postprandial blood glucose, the differences in glucose response between land and aquatic exercise are unclear. Thus, we examined the effect of different modes of exercise with same energy expenditure following glucose ingestion on carbohydrate metabolism. Ten healthy sedentary men (age, 22 ± 1 years) participated in this study. All subjects performed each of three exercise modes (cycling, walking and aquatic exercise) for 30 min after ingestion of a 75-g glucose solution with 1–2 weeks between trials. The exercise intensity was set at 40% of the maximum oxygen uptake that occurred during cycling. The velocity during walking and the target heart rate during aquatic exercise were predetermined in a pretest. The plasma glucose concentration at 30 min after exercise was significantly lower with aquatic exercise compared to that with cycling and walking (P<0·05). However, there were no significant differences among the three exercise modes in respiratory exchange ratio. On the other hand, serum free fatty acid concentration with aquatic exercise was significantly higher at 120 min after exercise compared with that after walking (P<0·05). These results suggest that aquatic exercise reduces postprandial blood glucose compared with both cycling and walking with the same energy expenditure. Aquatic exercise shows potential as an exercise prescription to prevent postprandial hyperglycaemia.