Handgrip strength across generations: An analysis of 1,158,069 Japanese children and adolescents from 57 years of national surveillance (1967-2023).

Abstract

Handgrip strength (HGS) is a widely used indicator of muscular strength that offers important insights into population health. While the literature has examined period effects-year-by-year changes in HGS- the authors are unaware of any study that has systematically investigated cohort effects, which may offer a more nuanced understanding of the generational shifts in HGS. This study aimed to examine the generational differences in the development of HGS among Japanese children and adolescents. Repeated, nationally-representative, annual, cross-sectional data on HGS were obtained from the Japan Sports Agency, covering 1,158,069 Japanese children and adolescents aged 10-17 years between 1967 and 2023. Temporal trends in absolute and relative HGS were estimated using sample-weighted regression models relating the year of testing to the mean HGS. To assess generational differences in HGS development, 10 synthetic birth cohorts were constructed at 5-year intervals from 1960 to 2005. Each cohort was tracked longitudinally in a repeated cross-sectional manner from age 10 to 17, allowing comparisons of both the annual strength velocity and the age at peak strength velocity across cohorts. A small but consistent decline in both absolute and relative HGS was observed over the 57-year period, with more pronounced declines observed since the 1990s (mean change per decade: boys, -1.6% [95% CI: -1.9%, -1.3%]; girls, -1.4% [95% CI: -1.7%, -1.2%]). Cohort analyses further revealed that the annual strength velocity was consistently lower at all ages in more recent cohorts (e.g., 2005 birth cohort) than in earlier cohorts (e.g., 1960 birth cohort), although the age at peak strength velocity remained steady. These findings suggest that children's HGS has progressively declined across generations, with more recent cohorts showing smaller age-related improvement. Given the well-established associations between HGS and multiple health outcomes, the observed decrease in HGS suggests a corresponding decline in population health.