Association Between Physical Literacy and Quality of Life Among Japanese Adults: The Mediating Role of Moderate to Vigorous Physical Activity

Background/Objectives: Physical literacy (PL) is increasingly being recognized as an important factor associated with physical activity participation and health outcomes. However, evidence remains limited regarding the association between PL and quality of life (QOL) in adults, particularly the statistical indirect association through moderate-to-vigorous physical activity (MVPA). Therefore, this cross-sectional study aimed to examine the associations among PL, MVPA, and QOL in Japanese adults and to assess the statistical indirect association between PL and QOL through MVPA. Methods: Japanese adults aged 18–64 years were recruited from a commercial online survey panel using age- and sex-quota sampling in 2023. After excluding incomplete or inconsistent responses and participants with missing or incomplete MVPA data, 861 participants were ultimately included. PL, QOL, and MVPA were assessed using the Physical Literacy for Life tool, World Health Organization QOL-26, and International Physical Activity Questionnaire, respectively. Associations among PL, MVPA, and QOL were examined using Pearson’s correlations, multiple linear regression, and mediation analysis with PROCESS macro (Model 4). Results: PL was positively correlated with MVPA (r = 0.257, p < 0.01) and QOL (r = 0.416, p < 0.01); MVPA was positively correlated with QOL (r = 0.248, p < 0.01). PL remained significantly associated with QOL after including MVPA and covariates (β = 0.374, p < 0.01). The statistical indirect association between PL and QOL through MVPA was significant (b = 0.0011, BootSE = 0.0003, 95% bootstrap confidence intervals: 0.0005–0.0018), indicating a modest indirect association through MVPA. Conclusions: PL was positively associated with QOL among Japanese adults, and MVPA partially explained this association in a statistical mediation model.