Effects of Rapid Weight Loss and Wrestling on Muscle Glycogen Concentration

Abstract

To examine the effect of energy restriction and wrestling on muscle glycogen content in highly-trained male wrestlers. Randomized, unblinded intervention trial. McMaster University Nutrition and Metabolism Research Laboratory. Twelve highly trained male wrestlers volunteered as subjects and were randomly assigned to one of two groups (Group A, n = 6; Group B, n = 6) as defined below. All subjects were free of medical conditions that would preclude participation in the study and all had performed rapid weight loss at least three times/year with no medical complications. Group A: simulated wrestling tournament, four 5-min wrestling bouts ( > 7 h) following a 5% body weight loss and 17 h repletion period; Group B: 5% weight loss through energy restriction (1,141 kcal/day), exercise, fluid restriction, and dehydration methods (sauna) > 72 h. Group A: muscle glycogen content before and after wrestling tournament and plasma lactate after each bout; Group B: muscle glycogen before and after weight loss. Group A: no significant effect on muscle glycogen concentration, yet large increases were observed in blood lactate concentrations (up to 14.7 mmol/L); Group B: weight loss resulted in a 54% (p < 0.018) reduction in muscle glycogen concentration. The weight loss methods commonly performed by wrestlers resulted in large decreases in muscle glycogen concentration that were largely reversed during the 17-h repletion period between weigh-in and the start of the competition; participation in a wrestling tournament did not have a significant impact upon biceps brachii glycogen concentration when ad libitum feeding is allowed between matches.