Purpose: To investigate the predictive ability of muscle cross-sectional area (MCSA) and body mass on bone mineral content, compressive bone strength index (BSI c ), and the polar stress-strain index (SSI p ) of the forearms and lower legs of middle-aged adults. Methods: A total of 53 healthy adults (37 male, 16 female; mean age 50.4; SD 2.1 y) were scanned with peripheral quantitative computed tomography (pQCT) to measure radius and tibia total and cortical bone mineral content, BSI c , SSI p , and forearm and lower-leg MCSA (BSI c : 4% distal; SSI p and MCSA at 65% and 66% radius and tibia shaft sites, respectively). Multiple regression models adjusted for sex and height were used to assess the relative variance in radius or tibia bone outcomes predicted by body mass and/or forearm or lower-leg MCSA. Results: Forearm MCSA independently predicted total bone-mineral content, BSI c , and SSI p in radius (r partial ¼ 0.59, 0.56, 0.42). Body mass was a negative predictor of radius BSI c (r partial ¼ À0.32) and did not predict other radius outcomes when both body mass and MCSA were forced in the models. In the lower leg shaft, MCSA, and body mass predicted bone content and strength similarly when independently added to the models with sex and height. Conclusions: Forearm MCSA was a dominant predictor of radius bone content and estimated strength. In the tibia, both body mass and lower-leg MCSA contributed to predicting bone content and estimated strength.Key Words: body weight; bone and bones; tomography scanners, X-ray computed; radius; muscle, skeletal; tibia. RÉ SUMÉObjectif : É tudier la capacité pré dictive de la mesure de l'aire de la fibre perpendiculaire à son sens longitudinal d'un muscle (mesure dite de la « MCSA ») et du poids corporel sur le contenu miné ral osseux, sur l'indice de force de compression de l'os (BSI c ) et sur l'indice tension-extension polaire (SSI p ) de l'avant-bras et de la portion infé rieure de la jambe chez les adultes d'â ge moyen. Mé thode : Au total, 53 adultes en bonne santé (37 hommes, 16 femmes; â ge moyen : 50,4 ans; é cart-type de 2,1 ans) ont subi une tomographie pé riphé rique quantitative par ordinateur (pQCT) en vue de mesurer le contenu total et cortical en miné raux du radius et du tibia, le BSI c , le SSI p et la capacité pré dictive de la section transversale de l'avant-bras et de la portion infé rieure de la jambe (BSI c : 4 % distal; SSI p et MCSA de 65 % et de 66 % pour le radius et le tibia, respectivement). De multiples modè les de ré gression adapté s en fonction du sexe et de la grandeur des participants ont é té utilisé s pour é valuer les variations relatives dans les ré sultats pour le radius ou le tibia projeté s à l'aide de la mesure du poids corporel et de la capacité pré dictive de la section transversale du muscle l'avant-bras ou de la portion infé rieure de la jambe. Ré sultats : La MSCA de l'avant-bras a permis de pré dire, à elle seule, le contenu miné ral osseux total, le BSI c et le SSI p du radius (r partiel ¼ 0,59, 0,56, 0,42). Le poids...

MTI for longitudinal studies in older postmenopausal women should be at least 2-6 years at the radius and tibia, with specific monitoring of the total and trabecular area, total density, and bone strength at the radius and total and trabecular density, total area, and bone strength at the tibia.

Muscle density may serve as a physiological marker in the assessment of lower leg muscular health and fall risk in community-dwelling elderly women. These results are limited to our study population who were mostly Caucasian. Prospective studies are required for verification.

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