Serum free testosterone, leptin and soluble leptin receptor changes in a 6-week strength-training programme

• Published in: British journal of nutrition Vol. 96; no. 6; pp. 1053 - 1059
• Main Authors: Ara, I., Perez-Gomez, J., Vicente-Rodriguez, G., Chavarren, J., Dorado, C., Calbet, J. A. L.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.12.2006
• Subjects: Absorptiometry, Photon; Adiposity; Adult; adults; Analysis of Variance; Biological and medical sciences; blood chemistry; body composition; body fat; duration; Exercise; Feeding. Feeding behavior; Free leptin index; Fundamental and applied biological sciences. Psychology; hormone receptors; Humans; lean body mass; leptin; Leptin - blood; Male; men; Muscle Strength; Obesity; Physical Education and Training; physical fitness; Receptors, Cell Surface - blood; Receptors, Leptin; strength training; testosterone; Testosterone - blood; Time Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Weight Loss; Free leptin index; Obesity; Exercise; Weight loss; Physical exercise; Physical training; Testosterone receptor; Nutrition disorder; Index; Change; Free leptin index: Obesity: Weight loss: Exercise; Vertebrata; Mammalia; Leptin; Serum; Nutritional status; Strength
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1017/BJN20061956

Strength training is usually associated with a reduction in fat mass and with muscle hypertrophy. The aim of the present study was to examine whether the serum free leptin index (FLI), measured by the molar excess of soluble leptin receptor (sOB-R) over leptin, is increased by 6 weeks of strength training. Eighteen male, physical education students were randomly assigned to two groups: a strength-training (n 12) and a control group (n 6). Body composition (lean body mass and body fat) determined by dual-energy X-ray absorptiometry (DXA), muscle performance and leptin, sOB-R, total testosterone and free testosterone concentrations were determined before and after training. Fat mass was reduced by 1 kg with strength training (P < 0·05). Lean body mass of trained extremities was increased by 3 % (P < 0·05), while the concentration of free testosterone in serum was reduced by 17 % (P < 0·05) after training. However, despite the reduction in fat mass and free testosterone, serum leptin concentration was not significantly affected by strength training, even after accounting for the differences in body fat. By contrast, for a given fat mass, the sOB-R was increased by 13 % (P < 0·05) at the end of the strength-training programme, although the molar excess of sOB-R over leptin remained unchanged. Therefore, the quantity of free leptin available to bind to the target tissues was not significantly affected by the short strength-training programme, which elicited a 7 % reduction in fat mass.