Plasma leptin concentrations in physically active men and women in relation to fat mass, fat free mass and selected biochemical variables
Journal Title: Biology of Sport - Year 2006, Vol 23, Issue 1
Abstract
The plasma leptin concentration depends on many factors with a substantial role played by physical activity. The aim of this study was the evaluation of the effects of body fat and fat free mass as well circulating glucose and cortisol on plasma leptin concentrations in active men and women. A total of 26 physical education students (13 men and 13 women)- took part in the study. Their physical activity during the study was only thatrequired by theie study program. No one was engaged in high-performance sports. Fasting blood samples were taken from the antecubital vein into lithium heparin tubes and centrifuged to separate plasma specimens. Plasma leptin levels were determined using radioimmunoassay and commercial kits (Linco, USA). Cortisol was determined by means of ELISA method and IBL kits (Germany). Glucose was assayed by the oxidase method using Randox commercial kits (Randox Laboratories, Great Britain). Body fat was estimated using the BIA method (RJL System INC., USA). Despite the lack of difference in fat mass between sexes circulating leptin in women (6.5 ng•ml-1) was significantly higher than in men (2.4 ng•ml-1). Plasma leptin concentrations in both men and women were not correlated with circulating glucose and cortisol. Moreover, neither in men nor in women were they correlated with the percent of body fat. In contrast, in men plasma leptin levels were significantly correlated with fat mass expressed in kilograms (r=0.56; p<0.05). In women circulating leptin was significantly and inversely correlated with the ratio of fat-free mass to fat mass (r=-0.71; p<0.006). Our results indicate that the effect of body fat on plasma leptin concentrations differs in active men and women, probably due to pronounced fat-free mass effects on plasma hormone levels in women but not in men.
Authors and Affiliations
G Lutosławska, B Wit
Keywords
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