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Purpose

This study was designed to determine whether serum leptin levels were affected by a 5-d military course after 3 wk of combat training.

Methods

26 male soldiers (mean age= 21+/-2 yr) were examined at the beginning of the training program and just at the end of the 5-d course. The combination of continuous heavy physical activity and sleep deprivation led to energy deficiency. Blood samples were analyzed for serum leptin, insulin, cortisol, adrenocorticotropin (ACTH), and testosterone; plasma was analyzed for free fatty acids (FFA), glycerol, glucose, and catecholamines.

Results

At the end of the 5-d course, there was a significant reduction in serum leptin (0.40+/-0.04 ng x mL (-1) versus 1.47+/-0.14 ng x mL (-1),< 0.001), ie, a mean decrease of 67.00+/-3.75%. Plasma norepinephrine and dopamine rose significantly from 296+/-17 ng x L (-1) to 672+/-48 ng x L (-1) and 23+/-3 ng x L (-1) to 40+/-5 ng x L (-1)(< 0.001 and< 0.01, respectively), whereas epinephrine remained unchanged. Serum concentrations of the anabolic hormone, insulin, fell from 31.17+/-3.03 microU x mL (-1) to 17.79+/-1.58 microU x mL (-1)(< 0.001), whereas plasma FFA and glycerol were increased (< 0.001,< 0.05, respectively). A statistically significant correlation appeared between the changes in leptin and insulin (r= 0.5306,< 0.01). Serum testosterone decreased significantly (< 0.001), whereas serum cortisol, ACTH, and plasma glucose were unchanged at the end of the course. The training program had no significant effect on mean body mass index.

Conclusion

A 4-wk strenuous military training program, which induced an energy deficiency, reduced serum leptin to …