Discordance in the decline in regional lean and bone mass with advancing age

Abstract

To investigate whether regional mineral-free lean mass (lean mass) and bone mineral density (BMD) decrease equally with advancing age. Subjects were 420 premenopausal women and 239 postmenopausal women with right-side dominance. Age, height, weight, and body mass index were recorded. Lean mass of the arms, trunk and legs were measured by dual-energy X-ray absorptiometry (DEXA). BMD of the same segmental regions was measured by DEXA. Trunk and bilateral leg lean mass were inversely correlated to age (r = -0.240, P < 0.0001, -0.167, P < 0.0001, and -0.183, P < 0.0001, respectively), but arm lean mass did not decrease with aging. Regional lean mass was positively correlated to regional BMD (r = 0.284-0.449, P < 0.0001). BMD was inversely correlated to age in all segmental regions (r = -0.586 to -0.449, P < 0.0001). Decline in regional lean mass and decline in BMD with advancing age are discordant. Arm lean mass may not contribute to 'age-related decline' in arm BMD, because arm lean mass does not decrease with advancing age in the general population of women.