Muscle strength and functional mobility in relation to lean body mass in free-living frail elderly women.

OBJECTIVES: (1) To describe body composition of the frail elderly, (2) To relate lean body mass to muscle strength and functional ability, and (3) To assess temporal stability of strength measures and index of functional ability.

DESIGN: Cross-sectional study.

SETTING: Community-dwelling.

SUBJECTS: Thirty frail elderly women (81.5 +/- 7 y) recruited from residences or out-patient facilities.

METHODS: Total body fat and fat-free mass (FFM) were determined using multi-frequency bioelectrical impedance analysis and predicted from anthropometry. Handgrip strength, biceps and quadriceps strength, functional capacities (Timed 'Up & Go') as well as self-perceived health and functional status were measured. Reliability was assessed using two separate observations made one week apart by the same examiner.

RESULTS: Mean height, weight and body mass index were 1.52 +/- 0.04 m, 60.4 +/- 10.7 kg and 26.0 +/- 4.8 kg/m2 respectively. FFM (34.1 +/- 4.6 kg) was lower than previous reports for autonomous elderly females and associated with all measures of muscle strength (Pearson's r = 0.42-0.62, P < or = 0.02), but not with performance on the Timed 'Up & Go' or self-perceived health and functional status. Strength measures correlated significantly with different subscales of self-perceived functional capacities and were significantly lower among women with a low %FFM (n = 19) and those reporting pain (n = 11) as compared to other women. Excellent temporal stability for muscle and functional measures was observed (ICC = 0.80-0.90).

CONCLUSIONS: Muscle strength was strongly related to FFM in free-living frail elderly women especially in the absence of pain.