Author(s): ZHANG, X., ZHU, J.R., MENG, Q., WANG, J.J., FAN, C.Q., FENG, Q., Institution: CHINA INSTITUTION OF SPORT SCIENCE, Country: CHINA, Abstract-ID: 1208

INTRODUCTION:
Low muscle strength is a well-established biomarker of functional capacity, disability risk, and healthy aging. As populations undergo rapid urbanization and demographic transition, secular changes in muscle strength may substantially affect future health burden. However, long-term regional patterns remain insufficiently understood in large developing countries.To examine 20-year age–period–cohort (APC) trends in low muscle strength among Chinese adults and to explore regional disparities across seven major geographical areas.
METHODS:
Data were derived from five waves of the National Physical Fitness Surveillance conducted between 2000 and 2020 (n = 854,897). Survey waves represented five calendar periods: 1998–2002, 2003–2007, 2008–2012, 2013–2017, and 2018–2022. Adults aged 20–69 years were categorized into ten five-year age groups (20–24 to 65–69 years), generating 14 birth cohorts from 1935–1939 to 2000–2004.China was divided into seven geographical regions: Northeast, North, South, Northwest, East, Central, and Southwest China. Handgrip strength was used to define low muscle strength according to standardized national criteria. Weighted logistic regression models estimated regional risks, and APC modeling was applied to disentangle independent age, period, and cohort effects, allowing identification of net drift and generational shifts.
RESULTS:
Marked regional divergence was observed over the 20-year period. South China demonstrated the most pronounced increase in prevalence, rising from 2.8% in 2000 to 6.6% in 2020 (+3.8 percentage points), shifting from the lowest to the highest national level. In contrast, North China showed minimal fluctuation (4.1%–4.8%). Northeast and North China experienced overall declines, whereas East and Central China showed modest increases. Northwest China remained relatively stable at a comparatively favorable national level, while Southwest China consistently maintained a relatively high prevalence across two decades. Significant interregional differences were present in each survey year (p < 0.001).
APC analyses revealed positive net drift in all regions except Northeast and North China. The steepest annual increase was observed in South China (6.531%, 95% CI: 5.510%–7.561%), followed by East (3.095%), Central (2.217%), Northwest (1.998%), and Southwest China (1.336%). Age effects demonstrated progressive risk accumulation with advancing age, while cohort patterns suggested deterioration among more recent birth cohorts in several regions, particularly in rapidly urbanizing areas.
CONCLUSION:
Over two decades, low muscle strength among Chinese adults has exhibited substantial regional heterogeneity and emerging cohort-related deterioration. These findings highlight the urgent need for region-specific resistance training promotion and muscle-strengthening strategies, particularly in areas undergoing rapid socioeconomic transition. Addressing generational declines in muscle strength may be critical for mitigating future functional impairment.