Abstract
BACKGROUND: Loss of muscle strength exerts a considerable impact on the quality of life and mortality of older adults. The present household survey study measured body composition and muscle strength with the aim of analyzing the roles of low lean mass, low muscle strength and obesity in stair negotiation ability and the effect of comorbidities on the relationship between body composition and functional capacity. METHODS: Body composition was assessed using bioelectrical impedance analysis and muscle strength was assessed with a hand grip dynamometer. The study population comprised individuals >55 years of age from a medium-sized Brazilian municipality. The sample included 451 participants. RESULTS: A total of 368 subjects were interviewed; their ages varied from 56 to 91 years. Among males, low muscle strength was associated with stair negotiation difficulty independent of muscle mass, age and obesity but muscle mass was not. However, when we analyzed comorbidities and body composition jointly, chronic lower limb pain and obesity were independently associated with stair negotiation difficulty but body composition and age were not. Among women, after comorbidities were included into the model, low muscle strength and obesity remained associated with stair negotiation difficulty as chronic lower limb pain and depression. The relationship between muscle function and comorbidities is discussed in this article.