ABSTRACT

　The purpose of the present study was to examine the effect of feeding status before endurance exercise on the incidence of hypoglycemia after pre-exercise ingestion of carbohydrate, and to elucidate the characteristics of individuals with high susceptibility to hypoglycemia after pre-exercise ingestion of carbohydrate. Sixteen subjects performed 60min cycle ergometer exercises at 75%VO₂max in overnight fasted and fed (3h after breakfast) states in random order. In both conditions, they consumed 500ml of a beverage containing 150 g of glucose 30min before the start of exercise. The criterion of hypoglycemia was set at 70mg/dL. In both conditions, mean plasma glucose levels did not drop below 70mg/dL 15min after the start of exercise. In the fed state, plasma glucose levels dropped transiently below 70mg/dL in 7 subjects, who showed substantially higher VO₂max, while plasma glucose levels remained above this level in the other subjects. On the other hand, 5 subjects developed transient hypoglycemia in the fasted state and their serum insulin levels at the onset of exercise and insulinogenic index were significantly higher than that in the other subjects who did not demonstrate a decline in plasma glucose. In conclusion, the present study demonstrated that pre-exercise ingestion of carbohydrate 30 min before endurance exercise causes hypoglycemia in several individuals regardless of feeding status. Furthermore, subjects with higher aerobic fitness and enhanced insulin secretory capacity seem to be more prone to hypoglycemia following pre-exercise carbohydrate ingestion under fed and fasted conditions, respectively.

DESCENTE SPORTS SCIENCE Vol.38/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE