Loss of muscle strength, mass (sarcopenia), and quality (specific force) and its relationship with functional limitation and physical disability: the Concord Health and Ageing in Men Project

OBJECTIVES: To determine the association between loss of muscle strength, mass, and quality and functional limitation and physical disability in older men. DESIGN: Cross‐sectional study of older men participating in the Concord Health and Ageing in Men Project (CHAMP). SETTING: Elderly men living in a defined geographical region in Sydney, Australia. PARTICIPANTS: One thousand seven hundred five community‐dwelling men aged 70 and older who participated in the baseline assessments of CHAMP. MEASUREMENTS: Upper and lower extremity strength were measured using dynamometers for grip and quadriceps strength. Appendicular skeletal lean mass was assessed using dual X‐ray absorptiometry. Muscle quality was defined as the ratio of strength to mass in upper and lower extremities. For each parameter, subjects in the lowest 20% of the distribution were defined as below normal. Functional limitation was assessed according to self‐report and objective lower extremity performance measures. Physical disability was measured according to self‐report questionnaire. RESULTS: After adjusting for important confounders, the prevalence ratio (PR) for poor quadriceps strength and self‐reported functional limitation was 1.91 (95% confidence interval (CI)=1.10–2.40); for performance‐based functional limitation the PR was 1.81 (95% CI=1.45–2.24). The adjusted PR for poor grip strength and physical disability in instrumental activities of daily living (IADLs) was 1.37 (95% CI=1.20–1.56). The adjusted PR for low skeletal lean mass (adjusted for fat mass) and physical disability in basic activities of daily living was 2.08 (95% CI=1.37–3.15). For muscle quality, the PR for lower extremity specific force and functional limitation and physical disability was stronger than upper extremity specific force. CONCLUSION: Muscle strength is the single best measure of age‐related muscle change and is associated with physical disability in IADLs and functional limitation.