The association between muscle mass and change in physical functioning in older adults: a systematic review and meta-analysis of prospective studies.

PURPOSE

The aim of this review is to investigate the prospective association between muscle mass and physical functioning in older adults, and to explore sources of variability in this association.

METHODS

Three databases were searched for prospective, observational studies investigating any assessment of muscle mass and functional decline in older adults (mean age 65 + years). 72 studies were included. Meta-analyses using results of the most adjusted statistical models were performed using Review Manager version 5.3.5.

RESULTS

Most studies were conducted in the community setting (n = 64) and used incident ADL limitations/disability as outcome (n = 44). Across studies, 6 body composition methods and 34 different parameters of muscle mass were used, including ratios. Average follow-up time was 46 months. For low versus higher muscle mass (n = 25), the overall odds ratio (OR) for functional decline was 1.23 (95% CI 1.10-1.37, I = 70%). Per SD higher muscle mass (n = 15), the overall OR was 0.89 (0.83-0.96, 76%). In general, no associations were observed when no adjustment for body size, or for body height only, was made. Associations were generally stronger when muscle mass was expressed as ratio of body weight, BMI or fat mass, or when more accurate body composition methods or objective performance tests were used.

CONCLUSION

In contrast to earlier reviews, this updated review shows that lower muscle mass is associated with higher risk of functional decline in older adults. Earlier observed variability in this association is explained by body composition method, body size adjustment, and type of physical functioning outcome.