Abstract
Delayed marriage and childbirth often result in individuals becoming grandparents in middle and older age, coinciding with significant physical transitions. This study examines the relationship between the intensity of grandparental childcare, measured in terms of time-commitment over the last year, and relative handgrip strength among South Korea adults aged 45-84. Data from 3,742 participants with grandchildren were analyzed using the 2008-2010 waves of the Korean Longitudinal Study of Aging. After applying propensity score matching, a final sample of 286 participants was analyzed with multivariate logistic regression model. Results showed that grandparents who provided childcare for an average of less than 40 h per week (Odds Ratio [OR] = 3.62) were more likely to have lower handgrip strength compared to those without caregiving experience. Additionally, those over the age of 65 showed a similar trend (OR = 2.76). Conversely, grandparents with positive self-rated health were less likely to exhibit lower handgrip strength than those rating their health as moderate (OR = 0.28). Grandparents who provided care for more than half the year were also less likely to have lower handgrip strength than those who provided less frequent care (OR = 0.26). This study highlights grandparental childcare as both a vital family support mechanism and a factor influencing physical health. Findings on caregiving intensity, particularly the role of moderate weekly childcare hours and longer terms involvement, underscore the importance of aligning caregiving commitments with grandparents' health perceptions and capacities. Developing guidelines for optimal childcare duration and recommending physical activities tailored to support grandparents' well-being would further promote healthy aging within a family-centered caregiving system.