Lower serum leptin concentrations in rugby players in comparison with healthy non-sporting subjects - relationships to anthropometric and biochemicalparameters

Leptin is a protein hormone synthesized by adipocytes. Its serum concentrat ions reflect the total body fat content. Serum leptin concentrations are si gnificantly higher in obese than in lean people and in women than in men. H owever little information about the influence of physical activity on serum leptin concentrations is available. We have compared the body weight, the body mass index (BMI), the body fat content (measured by caliper as skinfol d thickness) and the serum concentrations of leptin, triglycerides, total, high density and low density lipoprotein (LDL) cholesterol in 14 top rugby players and 10 healthy controls. We found that serum leptin, total and LDL cholesterol concentrations were significantly lower in the rugby players gr oup than in the control subjects. The body weight and BMI were significantl y higher in the rugby players, while the body fat content was only slightly (non-significantly) higher in the control group. The serum leptin concentr ations in both groups positively correlated with the BMI and body fat conte nt and also with LDL concentrations in the control group. The serum leptin concentrations in the rugby players were lower than in the non-sporting sub jects despite a similar body fat content in both groups. We would therefore suggest the possibility that regular hard physical training decreases seru m leptin concentrations not only by the decrease of total body fat content, but also by a separate mechanism, which is not directly dependent on the c hanges in the amount of body adipose tissue.