Age-specific comparisons in the rate of force development of toe pressure strength and its association with the timed up and go test

Key summary points Aim The aim of this study was to examine the association between Rate of Force Development (RFD) of toe pressure strength and the timed up and go test (TUG) by age group. Findings RFD of toe pressure strength in older adults was significantly lower than in younger adults. A significant association between TUG and RFD of toe pressure strength was found only in the older adults. Message The results encourage us to focus not only on maximal muscle strength but also on RFD with regard to toe pressure strength in older adults. Additionally, it was suggested that an approach to RFD of toe pressure strength could improve sitting, standing, and walking in older adults. Purpose It has recently been recommended that Rate of Force Development (RFD) be evaluated in addition to maximal muscle strength. There are no studies on RFD of toe pressure strength, and its importance in older adults and the extent to which it is associated with aging needs to be clarified. This study purpose was to examine the association between the RFD of toe pressure strength and timed up and go test (TUG) in an age-specific study. Methods This study is a cross-sectional study. Participants in the study included 159 younger adults (26.3 ± 13.1 years, 52% male) and 88 older adults (75.0 ± 6.2 years, 26% male). The RFD of toe pressure strength was determined from the force–time curve obtained during the toe pressure strength assessment, and the ability to exert maximum muscle force in the shortest possible time was assessed. Regression analysis was performed for each group to test the association between RFD of toe pressure strength and TUG by age. Results Younger adults showed no association between TUG and RFD of toe pressure strength, and significant association between TUG and RFD of toe pressure strength was found only in the older adults (standard regression coefficient = − 0.19, p = 0.048). Conclusion This study showed a significant association between TUG and RFD of toe pressure strength in older adults. These findings show that RFD is one of the functions that should be assessed, particularly in older adults. Furthermore, it was suggested that approaching RFD could improve gait, standing, and sitting movements.