Prolonged muscle vibration reduces maximal voluntary knee extension performance in both the ipsilateral and the contralateral limb in man

Abstract

Previous studies have shown that prolonged vibration of the rectus femoris decreases maximal voluntary knee extension performance in the ipsilateral leg. In the present study, measurements of maximal voluntary isometric knee extension contractions with the ipsilateral (right) leg and the contralateral (left) leg were made immediately before and after vibration treatment. Significant reductions in maximal force and maximum rate of force generation occurred in both the ipsilateral and contralateral legs following 30 minutes of continuous vibration at both 30 Hz and 120 Hz, with 30 Hz causing the greatest ipsilateral effects. However, although the level of neural activation (iEMG) of the vibrated muscle (right rectus femoris) was reduced following 30 Hz vibration ( P=0.026), there were no significant changes occurring in a synergistic muscle (right vastus lateralis) or in either contralateral muscle. It was concluded that muscle vibration may act through spinal reflex pathways to influence the homonymous motoneuron pool. The effects on contralateral force but not specific muscle iEMG suggest an effect on heteronymous motoneuron pools or an effect acting on central descending drive to contralateral muscles. These findings may have implications for the rehabilitation of patients with an immobilised limb.

The Use of Vibration Training to Enhance Muscle Strength and Power

“…In the first cular disease and those that investigated the po-method, vibration is applied directly to the muscle tential for neuromuscular disorder associated belly [9,13,14] or the tendon [8] of the muscle being with long-term (years) exposure to vibration in trained, by a vibration unit that may either be held the occupational environment.…”

“…[8,9] Finally, the authors did not adtivities as well as for the preservation and improve-dress the effect of different vibration characteristics ment in functional aspects of daily life. Resistance (method of application, frequency and amplitude) or training is presently the most popular way to im-the time-effect (acute, acute-residual and chronic) of prove muscle strength and power.…”

Electromyographic assessment of muscle fatigue during isometric vibration training at varying frequencies

“…Direct application of vibration to the muscle has been reported to cause larger degrees of fatigue, probably due to the increased neuromuscular demands placed by vibration [8]. Previous work using vibration applied to hand muscles has also suggested an effect of vibration frequency on motor unit synchronization causing fatigue [10].…”

“…2, the EMG signal is detected by N r rows (7) and N c columns (8). Assuming the same signal shape s(n) to be present in each (bipolar) channel, the ML method is developed under the hypothesis that the signal x rc measured at the channel (r, c) in the r th row and c th column of the electrode grid can be modeled as…”

“…Whole body vibration platforms are the most widely adopted devices for vibration training and have been suggested to be an effective modality to exercise the lower limbs [5], [6]; alternative devices have also been proposed for the upper limbs [7]. Vibration training has been shown to enhance muscle strength and power, mainly due to the neuromuscular demands of such vibrating loads on skeletal muscles [8], [9], [6], [7]. These results seem to be partly due to a neuromuscular phenomenon named tonic vibration reflex (TVR) [9], [10].…”