Reliability of Time-to-boundary Measures Estimated from Center of Pressure during Single-leg Standing by Healthy Young Adults

抄録

[Purpose] Time-to-boundary (TTB) measures estimate the time it would take for center of pressure (COP) to reach the boundary of the base of support if COP were to continue on its trajectory at its instantaneous velocity. This study aimed to determine the reliability of TTB measures obtained from healthy young adults during single-leg standing. [Subjects and Methods] Thirteen young adults (11 male, 2 female) performed three, 30-second trials of single-leg standing on a force plate. Ground reaction forces were recorded at a sampling frequency of 50 Hz and the data from 10 to 20 seconds were analyzed. TTB measures were absolute minimum, mean of minimum and SD of minimum in the ML and AP directions. Traditional COP measures were mean velocity, SD of COP, range of COP in the ML and AP directions and root mean square area. [Results] The intraclass correlation coefficient (ICC_2.1) of TTB measures were ranged from 0.50 to 0.69 and those of the COP measures ranged from 0.17 to 0.64. [Conclusion] The reliabilities of TTB measures were slightly better than those of the traditional COP measures. Acceptable reliability of all TTB measures can be achieved when 3 trials are averaged during the same testing day.