A portable vibrator for muscle performance enhancement by means of direct muscle tendon stimulation

The unit was able to produce desired vibration characteristics (amplitude: 0.2-2 mm; frequency: 30-200 Hz). Test day, strapping force and joint angle had no significant effect on these characteristics (p > 0.05). Both amplitudes (0.5 and 1.2 mm) and all three frequencies (30, 65 and 100 Hz) tested, significantly enhanced EMG activity (p < 0.05), with 1.2 mm and both 65 and 100 Hz resulting in significantly greater enhancements (p < 0.05). Joint angle had no significant effect on these EMG results (p > 0.05). The day-to-day repeatability of EMG response was shown to be high (r = 0.76-0.90).