Sex- and age-specific normative values of lower extremity muscle power in Italian community-dwellers

Background: Muscle power is associated with health-related parameters. Simple equations were validated to estimate lower extremity muscle power measures based on the time to complete the five-repetition sit-to-stand test. The present study was conducted to provide lower extremity muscle power estimates and produce centile values in a large and relatively unselected population across a wide age spectrum. Methods: Data were from the Longevity Check-up 7+ (Lookup 7+) project, an ongoing initiative conducted in unconventional settings (e.g., exhibitions, shopping centres and health promotion campaigns) across Italy to foster adoption of healthy lifestyles. Absolute, relative, allometric and specific muscle power measures of the lower extremities were estimated using validated formulas. Cross-sectional centile and normative values for muscle power measures from 18 to 81+ years were produced for the two sexes. Smoothed normative curves for men and women were constructed using the lambda-mu-sigma method. Results: From 1 June 2015 to 31 October 2021, 13 515 participants were enrolled of whom 12 864 were eligible for the present study. Mean age was 55.9 years (standard deviation: 14.8 years; range: 18-98 years), and 7217 (56.%) were women. Absolute, relative, allometric and specific muscle power declined significantly with age. Specific patterns of decline were observed according to sex and muscle power parameter. Absolute muscle power peaked at 41-50 and 31-40 years in men and women, respectively. Afterwards, a decline rate of approximately 12% per decade was observed, regardless of sex. Relative muscle power showed the largest reduction with age, such that it was 40.6% and 46.4% smaller in men and women older than 80, respectively, compared with those aged 18-30 years. Age-related changes in allometric and specific muscle power measures were similar between men and women. Conclusions: Data from the Lookup 7+ project indicate that lower extremity muscle power estimated using simple equations is significantly associated with age. Sex-specific patterns of decline in absolute and relative muscle power were observed with age. Allometric and specific muscle power declined at a similar rate in men and women.