Handgrip Strength Is Inversely Associated With the Progression of Kidney Damage in a General Japanese Population: A Prospective Cohort Study.

Background Handgrip strength is an indicator of muscle function and a predictor of health outcomes. However, only a few studies have examined the association between handgrip strength and the development of kidney damage. This study aimed to investigate the longitudinal association of handgrip strength with kidney damage in a general Japanese population. Methods This prospective cohort study enrolled participants with normal kidney function who attended annual health check-ups in Ibaraki Prefecture, Japan, between April 2016 and March 2020. Clinical information, including data from blood and urine tests, physiological examinations, and handgrip strength tests, was collected at enrollment. Lifestyle information was also collected via a self-administered questionnaire. The study participants were followed up for the progression of kidney damage until March 2023. Relative handgrip strength was calculated by dividing the handgrip strength by the body mass index to adjust for differences in body mass. A Cox proportional hazards model was used to examine the relationship between relative handgrip strength and the progression of kidney damage. Results A total of 4304 participants with normal kidney function were enrolled in this study. During the mean follow-up period of approximately 4 years (SD 1.8 years), 15.4% of the participants developed kidney damage. After adjusting for covariates, higher relative handgrip strength was associated with a lower risk of kidney damage in men (HR = 0.63, 95% CI: 0.43 - 0.90; p = 0.012), but no significant association was observed in women. Conclusions Higher relative handgrip strength is associated with a lower risk of kidney damage in men. This finding highlights the importance of muscle strength in preventing kidney damage.