Effects of Rapid Weight Loss and Wrestling on Muscle Glycogen Concentration

OBJECTIVE: To examine the effect of energy restriction and wrestling on muscle glycogen content in highly-trained male wrestlers. DESIGN: Randomized, unblinded intervention trial. SETTING: McMaster University Nutrition and Metabolism Research Laboratory. PARTICIPANTS: 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. ASSESSMENT OF RISK FACTORS: 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. INTERVENTIONS: 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. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.