PURPOSE:Evaluate anthropometric measures and serum markers of myostatin pathway activity following different weight reduction protocols in wrestlers. METHODS:Subjects were randomly assigned to a gradual weight reduction (GWR) or rapid weight reduction (RWR) group. Food logs were collected for the duration of the study. Anthropometric measurements and serum samples were collected following an 8 hour fast at baseline and following the weight reduction intervention. Subjects reduced body mass by 4%. The GWR group restricted calories over 12 days while the RWR group restricted calories over two days. A series of 2x5 RM ANOVAs were conducted to examine differences in nutrient consumption while separate 2x2 RM ANOVAs were conducted to examine differences in anthropometric measures and serum markers. When applicable, Tukey post-hoc comparisons were conducted. Significance for all tests was set at p<0.05. RESULTS:There were no between group differences for any anthropometric measure (p>0.05). Subjects in the GWR and RWR group each experienced a significant reduction in body mass, fat mass, lean mass, and percent body fat (p<0.05). There were no between group differences in serum markers of myostatin pathway activity (p>0.05), but subjects in the RWR condition experienced a significant increase in serum myostatin (p<0.01), a decrease in follistatin (p< 0.01), and an increase in myostatin to follistatin ratio (p<0.001). CONCLUSION:Although there were no between group differences for any outcome variables, the serum myostatin to follistatin ratio was significantly increased in the RWR group, possibly signalling the early stages of skeletal muscle catabolism.

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