Effect of intense training on plasma leptin in male and female swimmers

Purpose: The purpose of this study was to determine whether fasting plasma leptin concentration was altered with an increase in training volume in com petitive male and female athletes. Methods: Intercollegiate male (N = 9) an d female (N = 12) swimmers were examined during the preseason and at two ti mes during the mid-season (mid-season 1 and mid-season 2) when training vol ume was relatively high (33,000 m.wk(-1)). Body composition (hydrostatic we ighing), energy intake and expenditure, and fasting plasma leptin concentra tion were measured. Results In the women, there was a significant (P < 0.05 ) decline in fat mass (2 kg) with the increase in training volume, which wa s not accompanied by a reduction in fasting leptin (12.8 +/- 1.5 vs 11.0 +/ - 1.2 vs 11.0 +/- 1.5 ng.mL(-1) for preseason, mid-season 1, and mid-season 2, respectively). In the men, there were no significant changes in body co mposition. body mass, or fasting leptin (4.4 +/- 0.8 vs 4.3 +/- 0.8 vs 4.6 +/- 0.8 ng.mL(-1), respectively). Conclusions: These findings suggest 1) pl asma leptin is not sensitive to an increase in training volume and 2) lepti n may not be indicative of changes in fat mass with an increase in training volume in female athletes. These data suggest that leptin may not be usefu l in monitoring relative training stress in athletes.