2012 Volume 24 Issue 2 Pages 191-196
[Purpose] This study examined the influence of aging on balance function through the reaction time of the ankle joint muscles. [Methods] Forty-nine subjects were classified into 3 age groups: aged 20 to 30 (group Y, 19 subjects); aged 60 to 74 (YO, 12); and over 75 (OO, 18). Functional reach (FR), single-leg standing with eyes closed (SLS), and plantar flexor strength, were measured. For the electromyogram responses, reaction time (RT), premotor time (PMT), motor time (MT) and anticipatory postural adjustments (APAs) were evaluated. [Results] Significant differences in FR and SLS were observed between Y and YO, and OO. In the standing position, significant differences in PMT were observed between Y and OO, and in MT among all age groups. For the APAs, significant differences were observed between Y and OO, and in the strength between Y and YO, and OO. Balance items appeared to correlate with the reaction time in the standing position. [Conclusion] The results of this study verify that the balance function declines with age. We demonstrated that a delay in central processing and slower muscle contractions are key factors in the age-related decline of the balance function.