Abstract

This study examined the effects of a pre-experimental period of arm exercise followed by a 24-h carbohydrate (CHO)-poor intake, intended to reduce initial hepatic glycogen levels, on substrate and endocrine responses during prolonged CHO-loaded leg exercise. 7 subjects pedaled a cycle ergometer for 60 min at 62 VO2 max in the following conditions: 1) after leg CHO loading followed by a 60-min arm exercise and a 24-h CHO-poor diet (CHO L+P), and 2) after leg CHO loading only (CHO L). Greater blood concentrations of free fatty acids, glycerol, norepinephrine, and epinephrine were observed in the CHO L+P as compared to the CHO L conditions at min 60 of exercise. Insulin concentration was significantly lower in the CHO L+P condition at rest and during exercise. There were no significant differences during exercise between the two conditions in blood glucose, lactate, glucagon, and cortisol concentrations. It is concluded that changes in blood glucose concentration do not solely account for metabolic and hormonal adaptations during prolonged leg exercise and that a pre-experimental period of arm exercise and CHO-poor diet may provide a stimulus for such adaptations. It is suggested that the liver glycogen content may be involved in the regulatory mechanism. Verf.-Referat