Effect of physical activity on bone mineral density assessed by limb dominance across the lifespan

Bone mineral density is higher in dominant vs. nondominant Limbs, implying that the greater use of dominant limbs in everyday activities results in th e deposition of more bone or that the dominant limb is genetically larger. The objective of the present study was to determine whether bone mineral de nsity differences between dominant and nondominant arms were greater in old er vs. younger women. To determine whether this was due to a greater lifeti me of preferential loading of the dominant arm, differences between dominan t and nondominant arms were compared to accumulated amounts of physical act ivities which emphasized use of the dominant arm. Bone mineral density of d ominant and nondominant arms was assessed by dual-energy X-ray absorptiomet ry in groups of younger (n = 35; age = 20.9) and older (n = 53; age = 57.4) women. The difference between arms was greater in the older vs. the younge r group (5.2% vs. 1.9%, respectively, P < 0.01). Within the older group, to tal lifetime energy expenditure during activities emphasizing loading of th e dominant arm correlated with the bone mineral difference between dominant and nondominant arms (r = 0.47, P < 0.01). This implies that a greater lif etime of preferential loading of the dominant arm in the older group result ed in a greater difference between arms. (C) 2000 Wiley-Liss, Inc.