Background
Age-related decline in muscle strength is associated with adverse clinical outcomes including fragility fracture. However, no previous study has compared its prevalence, and demographic and lifestyle associates, in comparable populations in different geographic regions. We considered this here.
Methods
We used 2 community based cohorts; UK study participants (1572 men; 1415 women) were recruited from the Hertfordshire Cohort Study, while Japanese participants (520 men; 1028 women) were recruited from the ROAD study. Lifestyle questionnaire data from the two cohorts were harmonised. Age-related muscle strength decline was measured in both studies using a dynamometer, with low values classified as grip strength of <30kg in men and <20kg in women.
Results
The median age of UK participants was 65.8 (IQR 63.5 – 67.8) years in men and 66.5 (IQR 64.5-68.7) years in women, while in Japan this was 68 (IQR 58-76) years in men and 67 (57-74) years in women. The prevalence of age-related muscle strength decline in the UK was 3.0% in men and 10.3% in women, lower than Japan (11.5% men and 16.1% women). In both cohorts, women were at greater risk of muscle strength decline (UK: OR 3.73, 95% CI 2.66,5.23, p<0.001; Japan: OR 1.47, 95% CI 1.07-2.01, p=0.02), while greater height was protective (p<0.001). Smoking was not associated with muscle strength decline in either cohort, though drinking alcohol was protective in Japanese women (OR 0.60, 95% CI 0.38-0.95, p=0.03). Age at leaving education was a predictor of age-related muscle strength decline in both cohorts, particularly in Japan, where more time spent in education was protective in both genders (p<0.001); in the UK, this was significant in women only (p=0.01).
Conclusions
Despite a different prevalence of age-related muscle strength decline in comparable cohorts in UK and Japan, the anthropometric and lifestyle determinants of the condition were very similar.