A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity

Abstract

Background:Whole-body vibration (WBV) induces reflex muscle activity andleads toincreased muscle strength. However, little is known about thephysiological mechanisms underlying theeffects ofwhole-body vibration onmuscular performance. Tonic vibration reflex is themost commonly cited mechanism to explain theeffects of whole-body vibration onmuscular performance, although there is noconclusive evidence thattonic vibration reflex occurs. Thebone myoregulation reflex is another neurological mechanism usedto ex-plain theeffects ofvibration onmuscular performance. Bone myor-egulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. Aims:Theaimof thisstudy wasto assess whether bonetissue affect-edvibration-induced reflex muscle activity andvibration-induced muscle strength gain. Study Design:A prospective, randomised, controlled, double-blind, parallel-group clinical trial.Methods:Thirty-four participants wererandomised intotwogroups. High-magnitude whole-body vibration wasapplied intheexercise group, whereas low-magnitude whole-body vibration exercises were applied in thecontrol group throughout 20sessions. Hipbone min-eraldensity, isokinetic muscle strength, andplasma sclerostin levels were measured. Thesurface electromyography datawere processed to obtain theRoot Mean Squares, which were normalised bymaxi-mal voluntarily contraction. Results:Intheexercise group, muscle strength increased intheright andleftkneeflexors (23.9%, p=0.004 and27.5%, p