Basal plasma leptin levels in healthy elderly males are related to physical fitness without impact on bone metabolism

Investigated the relationship between leptin levels or bone remodelling and physical fitness level in healthy elderly participants. Twenty women and 18 men (mean age 72.7 years, range 59-90) performed a maximal incremental exercise test to evaluate their maximal oxygen uptake (VOmax). Basal blood concentrations of bone biochemical markers (BM) and leptin were analysed. Women presented higher values of leptin than men (+34.7%, P=0.024), but no difference related to gender was observed for the other biological parameters. Leptin levels were positively correlated with Body Mass Index (BMI) in both genders. Whether adjusted or not for BMI, leptin was negatively correlated with VOmax only in men (r=-0.55, P=0.02 and r=-0.57, P=0.01, respectively). No relationship between VOmax or leptin and BM was observed, except for leptin and osteocalcin in men (r=-0.66, P=0.015). Our data suggest that neither physical fitness nor leptin level seems to have a noticeable effect in the regulation of bone cell activity in healthy elderly participants. In this specific population, physical fitness plays a crucial role on leptin secretion, independently of BMI variation, and this action appears to be sex-dependent.