Associations between toe grip strength and hallux valgus, toe curl ability, and foot arch height in Japanese adults aged 20 to 79 years: a cross-sectional study

BACKGROUND The associations between toe grip strength (TGS) and foot structure are not well known, although foot structure is inferred to affect TGS. This study investigated the associations between TGS and hallux valgus angle (HVA), toe curl ability, and foot arch height (FAH). METHODS This study analysed 227, 20 to 79-year-old, community-dwelling participants. TGS, HVA formed by the first metatarsal bone and the proximal phalanx of the hallux, toe curl ability (percentage) calculated as (foot length-flexed foot length)/foot length, and FAH (percentage) calculated as navicular height/truncated foot length were measured. To elucidate associations between TGS and foot structure, a correlation analysis and stepwise multivariate linear regression analyses were performed, based on the participant's sex. Pearson's correlation coefficients for TGS with age, height, weight, HVA, toe curl ability, and FAH were also calculated. In the stepwise, multivariate linear regression analyses, the independent variable was TGS and the dependent variables were those that significantly correlated with TGS, as shown by the Pearson's correlation coefficients. The significance level was set at 5%. RESULTS According to the Pearson's correlation coefficients, in men, TGS was significantly correlated with age, height, toe curl ability, and FAH. According to the stepwise multiple regression analysis, TGS correlated with age and toe curl ability (adjusted R(2)=0.22). In women, TGS was significantly correlated with age, height, and toe curl ability (adjusted R(2)=0.40). CONCLUSIONS TGS was associated with toe curl ability in both men and women. However, TGS was not associated with HVA and FAH in men or women. The results of this study may lead to the development of effective interventions to improve TGS. However, factors other than structure of the foot require more detailed investigation to clarify the factors contributing to TGS.