The association between age- and sex-related differences in muscle strength and physical performance in Chinese older adults: a 5-year prospective cohort study

The global demographic shift towards an aging population highlights the increasing prevalence of age-related health concerns, such as sarcopenia, predominantly observed in older adults. This study aimed to evaluate the prevalence of muscle strength and physical performance in older Chinese adults and to elucidate the association between handgrip strength (HGS), the Timed ‘Up and Go’ (TUG) test, and various anthropometric indices (i.e., height, weight). Participants were enrolled from the China Action on Spine and Hip Status (CASH) study (NTC 01758770). Data were gathered through handgrip strength assessment, the TUG test, anthropometric measurements, and EQ-5D evaluations. All measurements were repeated after an interval of five years. An adjusted linear regression model was employed to examine the relationship between percentage changes in HGS and TUG and changes in anthropometric variables, including height, weight, body mass index (BMI), and EQ-5D in both sexes. The study included 125 participants, with 75 women (60%) averaging 67.6 years (SD 5.0) and 50 men (40%) averaging 69.0 years (SD 5.4). Over the five-year period of the study, HGS showed significant decrease, while TUG and EQ-5D showed significant increases when comparing the group aged below 70 years (n = 49) (HGS: -1.5 ± 21.0) with those aged 70 years and above (n = 26) (TUG: 33.8 ± 27.2; EQ-5D: 50.7 ± 27.7). In contrast, male participants did not exhibit any significant differences across all variables, including height, weight, BMI, HGS, TUG, and EQ-5D, when comparing the under-70 age group (n = 32) with those aged 70 or over (n = 18). There were no significant associations between the five-year percent changes in height, weight, BMI, and EQ-5D in both women and men, with the five-year percent changes in HGS (p > 0.05). The five-year percent changes in TUG were significantly correlated with changes in weight (β = 1.1, 95% CI: 0.1-2.0, p < 0.05) and BMI (β = 1.1, 95% CI: 0.1–1.9, p < 0.05) only in females. However, the percent changes in TUG for males did not significantly differ in relation to the five-year percent changes in height, weight, BMI, and EQ-5D in men and in height and EQ-5D in women (p > 0.05). In conclusion, our study demonstrated a significant decrease in HGS for individuals aged 70 and above. Notably, while the five-year percent changes in TUG in females were associated with weight and BMI, this may suggest a greater vulnerability of older women to poorer physical performance outcomes compared to men. Future research should focus on identifying key demographic groups and developing tailored intervention strategies to mitigate declines in physical function with age.