Motor unit plasticity is currently incorporated into many professional and collegiate training regiments. Motor unit plasticity can be measured in many ways, the most important of which being neural firing frequency, EMG amplitude, muscle force output, pre-synaptic inhibition, and synchronization. Firing frequency is defined as the number of neuronal signals sent per second on one motoneuron. This frequency is measured in Hertz. Maximum firing frequency in humans typically ranges from 100–200 Hz. Studies incorporating electromyography have proven that adaptation mechanisms occurring as a result of resistance training can drastically increase the maximal firing frequency of a motoneuron. Firing frequency has been shown to
Vibration fatigue that are in correlation with those expected during the service-life of the product. To shorten the testing time, the amplitudes are amplified. The excitation spectra used are broad-band and can be evaluated most effectively using vibration-fatigue methods. Vibration fatigue Vibration fatigue is a mechanical engineering term describing material fatigue, caused by forced vibration of random nature. An excited structure responds according to its natural-dynamics modes, which results in a dynamic stress load in the material points. The process of material fatigue is thus governed largely by the shape of the excitation profile and the response it produces. As the profiles