Low lean tissue mass and physical performance as markers of sarcopenia in older men and women

Background: While declines in muscle mass and function occur in all individuals with advancing age, the extent and rate of decline vary in the general population. We aimed to determine the prevalence of low lean tissue mass combined with poor physical function as an indicator of sarcopenia among older men and women residing in southeastern Australia. Methods: The study involved men and women aged 60+ years from the Geelong Osteoporosis Study (GOS). Skeletal muscle mass was measured as total lean tissue mass by dual energy x-ray absorptiometry (DXA) and expressed as a percentage of body weight to generate the skeletal mass index (SMI); low lean mass was defined as SMI T-score <-1. Low muscle function was based on performance using “timed up-and-go” scores >10s. Physical activity scores were determined using a validated questionnaire for the elderly and falls were self-reported for the previous year. Associations between sarcopenia, physical activity and falls were determined using multivariable regression techniques. Results: Among 624 men, 233 had low SMI, 169 had low muscle performance and 81 had both, thus meeting criteria for sarcopenia. Among 436 women, 143 had low SMI, 179 had low muscle performance and 70 had both. A general age-related increase in the observed prevalence of sarcopenia appeared to be driven by an age-related increase in low performance. Sarcopenia was associated with lower physical activity scores. No association was detected between sarcopenia and falls for men but an association was observed for women (age-adjusted OR 1.87, 95% CI 1.11, 3.14). Conclusion: In our population, the prevalence of sarcopenia was 10.6% (95% CI 7.7, 13.4) for men and 14.5% (95% CI 10.8, 18.3) for women. Men and women with sarcopenia were habitually less active and, for women, sarcopenia was associated with increased likelihood of falls.