Trends in physical fitness among adults from Macao SAR between 2001 and 2020

Monitoring temporal trends in physical fitness among adults offers insights into population health and informs preventive health strategies. This study examined such trends among adults aged 20–69 years from the Macao Special Administrative Region (SAR) between 2001 and 2020. Repeated cross-sectional population-representative data were collected in 2001, 2005, 2010, 2015, and 2020 (n = 20,653). Objectively measured data on body size and physical fitness were analysed. Trends in means were assessed using generalised linear models, with different adjustment and stratification strategies for sex, age, height, and weight. The ratio of the coefficients of variation and visual analysis of percentile curves were used to evaluate trends in distributional characteristics. Declines were observed in lower body muscular power (ES = $$-$$0.34), lower back strength (ES = $$-$$0.55), flexibility, (ES = $$-$$0.16), balance (ES = $$-$$0.21), and reaction time (ES = $$-$$0.32) among young adults aged 20–39 years. Middle-aged adults aged 40–59 years showed declines in cardiorespiratory fitness (ES = $$-$$0.28), balance (ES = $$-$$0.18), and reaction time (ES = $$-$$0.46). Small improvements were observed in cardiorespiratory fitness (ES = 0.20) for young adults aged 20–39 years and reaction time (ES = 0.25) for older adults aged 60–69 years. Sex-specific temporal trends were observed in cardiorespiratory fitness, flexibility, balance, and reaction time across age groups. Distributional analyses revealed a widening gap across the population in fitness levels, particularly among lower-performing and younger adults. These findings indicate a general decline in physical fitness among young and middle-aged adults, particularly males, in Macao SAR from 2001 to 2020. This highlights the need for age- and equity-focused interventions. Maintaining and improving adult fitness is essential for long-term health, functional independence, and active ageing.