Relationship between balance ability and rate of force development of toe grip strength in young adults

Toe grip strength is used to evaluate toe muscle strength associated with dynamic and static balance ability. Although maximum voluntary contraction (MVC) has been widely measured as an outcome of toe grip strength, recent recommendations evaluate not only MVC but also the rate of force development (RFD), an index of instantaneous muscle strength exertion. The RFD, which measures the gradient of muscle strength change at regular time intervals following muscle exertion, is crucial for responding to the unexpected centre of pressure sway. In this study, we aimed to examine the relationship between balance ability and the RFD of toe grip strength.

A total of 23 healthy young men and 24 healthy young women (mean age, 20.5 years) participants were recruited. Their balance was measured by dividing the total trajectory length (mm) by the rectangular area (mm²)of the centre of pressure while standing on one leg for 40 s. Toe flexor strength, MCV, and RFD were measured using a toe grip dynamometer and normalised to body mass.

A significant negative correlation was observed between the RFD of toe grip strength and the rectangular area of the centre of pressure in the male group (-0.57 at RFD50, p < 0.005). In the female group, no association was noted between the RFD and centre of pressure parameters (-0.18 at RFD50, p = 0.411).

The RFD of the toe flexor strength may play a significant role in maintaining postural stability during one-leg standing in healthy young men.