Inter-arm asymmetry in bone mineral content and bone area in postmenopausal recreational tennis players

Abstract

Objective: To determine whether long-term recreational tennis participation is associated with increased bone and muscle mass in the dominant compared to the non-dominant arm, in postmenopausal tennis players. Methods: Dual-energy X-ray whole body scans were performed in 10 postmenopausal tennis players (mean±S.D.; 59.7±4.8 years) and 12 postmenopausal non-active women (62.8±7.2 years) matched for age and height. Tennis players started in this sport at 31.4±8.8 years, and had been playing for 26.8±6.8 years, at least 3 h per week. In addition, shoulder isokinetic muscular strength was also evaluated. Results: Tennis participation resulted in a lower whole mass and fat mass in both arms (P<0.05). Dominant arm muscle mass and shoulder joint isokinetic strength were essentially similar in both groups, however, the tennis players showed 8% greater bone mineral content and 7% greater osseous area in the dominant than in the non-dominant arm (P<0.05). No inter-arm differences were found in bone mineral density. A relationship was observed between the length of tennis participation and the degree of inter-arm asymmetry in bone mineral content (r=0.81, P<0.01) and bone area (r=0.78, P<0.01). However, the BMD of the arms was essentially similar in both groups. No differences were observed in femoral and lumbar bone mass and density between groups. Conclusions: Long-term tennis participation is associated with increased bone mass, but not BMD, in the dominant arm of postmenopausal tennis players. The magnitude of the inter-arm asymmetry of postmenopausal tennis players is proportional to the length of tennis participation.