Stationarity of surface electromyographic signals on isokinetic knee extension test

The present work tested the stationarity of surface electromyographic signals on two phases of the isokinetic knee extension test: velocity overshoot and isokinetic load range. Sixteen adult males participated as volunteers performing three isokinetic sets of ten repetitions of dominant knee extension at 60^o/s. The segments of myoelectric signals relating to each phase were submitted to the method of Kwiatkowiski, Phillips, Schmidt, and Shin (KPSS) for stationarity investigation. Results showed that the isokinetic load range is the only phase where the myoelectric analysis can be reliable. Velocity overshoot behaved as a nonstationary phase.