Physical performance measures in screening for reduced lean body mass in adult females with obesity

Background & aims: Little is known about the reduction of lean body mass (LBM) in obesity, or how to identify it in standard clinical settings. We therefore aimed to assess the prevalence of low LBM in adult females with obesity, and to identify the reliability of simple tools for its screening in this population. Methods and Results: Dual-energy X-ray absorptiometry (DXA) body composition assessment was used to categorise 147 female participants with obesity as with or without low LBM, according to the new definition that takes into account both appendicular lean mass (ALM) and body mass index (BMI)—ALM/BMI <0.512. Participants were also administered the six-minute walking test, handgrip-strength test and 4-metre gait-speed test. Of the sample of 147 participants, 93 (63.3%) met the criteria for reduced LBM. Stepwise multivariate logistic regression analysis showed that the six-minute walking test was the only independent test associated with low LBM (OR = 0.992, 95%CI 0.987–0.998). Receiver operating characteristic (ROC) curve analysis found that the discriminating cut-off points of the tests considered were 470 m, 3.30 s (gait speed = 1.2 m/sec) and 23.5 kg respectively; the 4-metre gait-speed test seems to provide the best balance of sensitivity and specificity, and the greatest discriminatory power at 90% sensitivity. Conclusions: Treatment-seeking adult females with obesity display a great prevalence of reduced LBM. The six-minute walking test was the only independent test associated with low LBM, but the 4-metre gait-speed test seems to be the most accurate functional test for screening for this condition in that population.