C. Jaffré

Hypoleptinaemia in extreme body mass models: The case of international rugby players

Leptinaemia has been poorly studied in athlete populations with the consequences of athletic hypoleptinaemia yet to be examined. Our aim was to determine if systemic leptinaemia is influenced in high body mass athletes. We recruited 24 rugby players (21.5+/-4.7 years; 11.8+/-2.9h/week) and 26 controls (22.3+/-3.1 years; 1.9+/-1.4h/week). BMD (whole body (WB), limbs, lumbar spine and non-dominant femur) and body composition (WB Lean Mass (LM) and FM) were measured by Dual X-ray Absorptiometry. Circulating levels of serum leptin (ng/ml), adiponectin (microg/ml), insulin (ng/ml), osteocalcin (ng/ml) and CTx (ng/ml) were assessed by ELISA assays. BMD were significantly higher in rugby players vs controls, at all bone sites, yet after adjustments for body mass index. They had significantly higher LM and FM but no differences in %FM. They had significantly higher osteocalcin but lower CTx, insulin and leptin concentrations. Leptin levels were strongly correlated to %FM (r=0.85, p<0.0001), as well as to absolute FM (r=0.77, p=0.0002), in the rugbymen group. Rugby practice was associated to a bone remodelling process in favour of bone formation. There was a significant hypoleptinaemia in our rugby players, while their percent FM was equivalent and absolute FM significantly higher than the control levels. These data suggest that leptin is under control of physical activity and not just fat mass.

Activité physique et remodelage osseux : étude chez une population de jeunes gymnastes☆

Aims – Intensive exercise is known to improve the bone mass acquisition. One of the main explanations consists in the mechanical strains exerted on the skeleton. Little is known about the effects of physical exercise on the bone remodelling process. Methods and results – The bone remodelling rate evaluated in a group of young female (24 gymnasts and 21 controls), using a bone resorption marker, the CrossLaps peptides CTx. We measured in our subjects the bone mineral density at the whole body and at six regional sites. The bone density was statistically higher in the gymnasts compared to the controls at all the specific sites. The CTx level corrected by urinary creatinine was significantly higher in the gymnasts, reflecting a faster bone remodelling rate. Conclusion – Intensive physical activity could improve the bone mineral acquisition probably by a stimulation of the bone remodelling activity.