Association of upper arm circumference at muscle flexion with lumbar spine bone mineral density

We investigated the association of upper arm circumference at muscle flexion with lumbar spine (L2-L4) bone mineral density (BMD) in 252 postmenopausal Japanese women (mean age, 62.0 +/- 7.6 years; range, 43-78 years) with right-side dominance. Age, age at menopause, years since menopause (YSM), weight, and height were recorded. Dominant upper arm circumference (cm) was measured at muscle flexion. Lumbar spine BMD was measured by dual-energy X-ray absorptiometry (DXA). Correlations between BMD and variables were determined using Pearson's correlation coefficient. Significant predictors of the lumbar spine BMD were determined using stepwise multiple regression analysis. Upper arm circumference, weight, and height were positively correlated with BMD (r = 0.397, 0.343, and 0.323, respectively), whereas YSM and age were inversely correlated with BMD (r = -0.415 and -0.392, respectively). On stepwise multiple regression analysis, YSM, upper arm circumference, and weight were significant predictors of BMD (R2 = 0.322, P < 0.0001). Predicted value of the lumbar spine BMD was calculated by the following formula: Predicted BMD = 0.249 - 0.0078 (YSM) + 0.016 (upper arm circumference) + 0.0046 (weight). Dominant upper arm circumference at muscle flexion in combination with YSM and weight is a useful predictor of lumbar spine BMD.