Age-Related Variations of Muscle Mass, Strength, and Physical Performance in Community-Dwellers: Results From the Milan EXPO Survey

Objectives: Declining muscle mass and function are hallmarks of the aging process. The preservation of muscle trophism may protect against various negative health outcomes. Age-and sex-specific curves of muscle mass, strength, and function, using data from a large sample of community-dwelling people, are necessary. Material and methods: Two surveys (Longevity Check-up and Very Important Protein [VIP]), conducted during EXPO 2015 in Milan, consisted of a population assessment aimed at evaluating the prevalence of specific health metrics in subjects outside of a research setting (n = 3206), with a special focus on muscle mass, strength, and function. Muscle mass was estimated by using mid-arm muscle circumference (MAMC) and calf circumference of the dominant side. Muscle strength and function were assessed through handgrip strength testing and repeated chair stand test, respectively. Results: The mean age of 3206 participants in the Longevity Check-up and VIP surveys was 51.9 years (SD 15.6, range 18-98 years), and 1694 (52.8%) were women. Cross-sectional inspection suggests that both calf circumference and MAMC decline nonlinearly with age and the rate of decline varies by gender. These measures are stable until 50 years and then begin to decrease slightly with age, with the effect being more evident in men than in women. The main effect of the age category was observed in muscle strength and physical performance parameters. Muscle strength declined significantly after 45 years of age, both in men and women (P <.001). The muscle quality of the upper extremities, defined as handgrip strength divided by MAMC, declined significantly with aging, as well (P <.001). The time to complete the chair stand test was similar from 18 years to 40 to 44 years, and then a linear decline in performing the test across age groups was observed, with an increased time of more than 3 seconds, both in men and women (P <.001). Conclusions: Muscle mass and strength curves may be used to extract reference values for subsequent use in research as well as in the clinical setting. In particular, the analyses of trajectories of muscle parameters may help identify cutoffs for the estimation of risk of adverse events. (C) 2016 AMDA - The Society for Post-Acute and Long-Term Care Medicine.