Prediction of time-to-exhaustion in the first dorsal interosseous muscle from early changes in surface electromyography parameters.

Introduction: In this study we evaluated the precision of the time-to-exhaustion (T(lim)) prediction from the early changes in surface electromyography (sEMG) of the first dorsal interosseous muscle.

Methods: Thirty subjects performed an index finger isometric abduction at 35% of maximal voluntary contraction (MVC) until exhaustion. Ten participants performed the same exercise at 50% MVC 1 week later. Changes in sEMG parameters across time were modeled using the area-ratio and the linear regression slope. T(lim) was plotted as a function of each of these indices of change, and the coefficient of determination (R(2)) was determined.

Results: Null to moderate R(2) (0.22 and 0.56 at 35% and 50% MVC, respectively) values were calculated. The best T(lim) estimation led to a high prediction error (21.6 ± 15.0% of T(lim) for the 50% MVC task).

Conclusions: Although the prediction of time-to-exhaustion is an appealing research topic, these results suggest that it cannot be done solely from sEMG.