*2.4.2. Muscle activity and the amount of skeletal muscle output are reduced by more than 20 minutes of vibration stimulation*

Vibration stimulation on a sustained maximum muscle contraction case can reduce the firing frequency of the nerve cells involved in the maximum contraction, and subsequently the muscle output will decrease. In addition, more than 20 minutes of vibration stimulation on quadriceps femoris muscle can bring on a reduction in the peak torque and integrated EMG.

If you apply these findings clinically, it is possible to suppress the excessive and abnormal muscle activity that occurs as a compensatory motion during action, and subsequently to let the patient have efficient training.

However, in patients with osteoarthritis of the knee and also in patients who have undergone ACL reconstruction and therefore need onerous training, no decrease of the peak torque and integrated EMG occurs after the vibration stimulation. Abnormal gamma motor neurons are believed to be involved, and the abnormality results from reduced afferent nerve activity of the joints.

All in all, clinical application of vibration stimulation on patients with musculoskeletal disorders awaits further trials because there remain some unsettled issues.
