Reliability and validity of a new measure of agility and equilibrium: the reaction balance test

Purpose. The evaluation has been limited to a single ability, such as agility or equilibrium, and has not been conducted in a series of movements. In addition, a measurement method that is less burdensome for the participants has not been established. In this study, we designed a new reaction balance test (RBT) that combines agility and equilibrium and examined its reliability and validity. Methods. The participants were 49 young people (17 males, 32 females). Their whole -body reaction time (WRT) and center of pressure (COP) during a 30 -second trial (COP30) of single -leg standing with open eyes were measured to determine their agility and equilibrium, respectively. Overall, 4 COP parameters were evaluated during COP30. For RBT, the participants were asked to quickly raise one leg after sensing a light stimulus and stand on the other leg for 10 seconds (COP10). The test evaluated their single -leg reaction time (SRT) and the same 4 parameters as those in COP30. Results. The intraclass correlation coefficients between agility (WRT and SRT) and equilibrium (total length [TL] at COP30 and COP10) were all > 0.81. In addition, no proportional error was observed for COP30 or COP10, only for TL of the nondominant leg. There were significant associations between WRT and SRT for agility and between COP30 and COP10 for equilibrium for TL. Conclusions. It was suggested that the reliability and validity of RBT could be improved by evaluating TL by using the dominant leg for agility and the non -dominant leg for equilibrium.