Tomographical description of tennis-loaded radius: reciprocal relation between bone size and volumetric BMD

Abstract

Effects of long-term tennis loading on volumetric bone mineral density (vBMD) and geometric properties of playing-arm radius were examined. Paired forearms of 16 tennis players (10 women) and 12 healthy controls (7 women), aged 18–24 yr, were scanned at mid and distal site by using peripheral quantitative computerized tomography. Tomographic data at midradius showed that tennis playing led to a slight decrease in cortical vBMD (−0.8% vs. nonplaying arm, P< 0.05) and increase both in periosteal and endocoritcal bone area (+15.2% for periosteal bone, P < 0.001; and +18.8% for endocortical bone, P < 0.001). These data suggest that, together with an increase in cortical thickness (+6.4%, P < 0.01), cortical drift toward periosteal direction resulted in improvement of mechanical characteristics of the playing-arm midradius. Enlargement of periosteal bone area was also observed at distal radius (+6.8%, P < 0.01), and the relative side-to-side difference in periosteal bone area was inversely related to that in trabecular vBMD ( r = −0.53, P < 0.05). We conclude that an improvement of mechanical properties of young adult bone in response to long-term exercise is related to geometric adaptation but less to changes in vBMD.