Effects of glucose ingestion at the onset of moderate-intensity, prolongedexercise in women as compared to men

To test glucose tolerance during exercise, the effects of oral glucose inge stion (0.5 g . kg(-1)) on plasma glucose and hormonal responses (insulin, c atecholamines) were investigated in 11 women [mean (SEM) age 21.6 (1.3) yea rs] and 10 men [22.0 (0.3) years] during cycle ergometer exercise (30 min a t 60% maximum oxygen consumption, (V) over dot O-2max) The two groups exhib ited similar (V) over dot O-2max values, when expressed per kg of lean body mass. Venous blood samples (5 ml) were withdrawn immediately before the ex ercise, during the exercise (at 3, 5, 10, 15 and 30 min) and at the 30th mi n of the recovery period. Glucose was ingested orally between the 2nd and t he 3rd min of the exercise. As compared to men, plasma glucose concentratio ns were lower in women during exercise (P < 0.05 at 3, 15 and 30 min) and a t the 30th min of the recovery period (P < 0.001), while plasma insulin con centrations were higher in women during exercise (P < 0.05 at 3, 15 and 30 min). The ratio of the area under the curve for glucose over the area under the curve for insulin was lower in women during exercise (P < 0.0002). A l inear relationship between glucose and insulin concentrations was found onl y for women during exercise (r = 0.615, P < 0.0001). No gender difference w as observed for the catecholamine concentration during exercise. In conclus ion, this study postulates that an oral glucose load given at the onset of a prolonged and moderate exercise bout induced lesser plasma glucose and gr eater insulin concentrations in women as compared to men. These data argue in favour of a greater glucose tolerance in women during exercise.