Non-linear growth trends of toe flexor muscle strength among children, adolescents, and young adults: a cross-sectional study.

PURPOSE: There are only a few studies on the muscular strength of the foot in children and adolescents; thus, the developmental pattern and normative data of these populations during growth are unclear. We sought to elucidate the developmental pattern of the foot muscle strength among children, adolescents, and young adults compared with that of the hand.

METHODS

A total of 747 children, adolescents, and young adults participated in this study, and their maximum isometric toe flexor strength (TFS), hand grip strength (HGS), and foot length were measured.

RESULTS

TFS was correlated with HGS (r = 0.785), age (r = 0.659), height (r = 0.757), body mass (r = 0.737), and foot length (r = 0.594). Multiple regression analyses revealed that TFS was correlated with age (β = 0.243 in boys; β = 0.461 in girls), squared value of age (age2; β = - 0.296 in boys; β = - 0.260 in girls), and body mass (β = 0.256 in boys; β = 0.311 in girls) in both sexes, indicating a non-linear relationship between age and TFS development. In a regression model for HGS, age was a significant variable, but not age2. HGS increased linearly from childhood until young adulthood, whereas TFS increased from childhood until adolescence and then levelled off.

CONCLUSION

Our results demonstrate that TFS has a different developmental pattern compared with HGS.