title: 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 and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity.
  
  
  OBJECTIVE
  The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain.
  
  
  METHODS
  A prospective, randomised, controlled, double-blind, parallel-group clinical trial.
  
  
  METHODS
  Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction.
  
  
  RESULTS
  In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035).
  
  
  CONCLUSIONS
  This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity.
  
  
  BACKGROUND
  ClinicalTrials.gov: NCT01310348.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Bağcılar Training and Research Hospital, İstanbul, Turkey.
authors.forename: Muharrem
authors.initials: M
authors.lastname: Cidem
authors.affiliation: Department of Physical Medicine and Rehabilitation, Bağcılar Training and Research Hospital, İstanbul, Turkey.
authors.forename: Ilhan
authors.initials: I
authors.lastname: Karacan
authors.affiliation: Department of Physical Medicine and Rehabilitation, İstanbul University İstanbul Medical Faculty, İstanbul, Turkey.
authors.forename: Demirhan
authors.initials: D
authors.lastname: Diraçoğlu
authors.affiliation: Department of Physical Medicine and Rehabilitation, İstanbul University İstanbul Medical Faculty, İstanbul, Turkey.
authors.forename: Aysel
authors.initials: A
authors.lastname: Yıldız
authors.affiliation: Department of Biochemistry, Bağcılar Training and Research Hospital, İstanbul, Turkey.
authors.forename: Suat Hayri
authors.initials: SH
authors.lastname: Küçük
authors.affiliation: Department of Physical Medicine and Rehabilitation, İstanbul University Cerrahpaşa Medical Faculty, İstanbul, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Uludağ
authors.affiliation: Department of Physical Medicine and Rehabilitation, İstanbul University Cerrahpaşa Medical Faculty, İstanbul, Turkey.
authors.forename: Kerem
authors.initials: K
authors.lastname: Gün
authors.affiliation: Department of Physical Medicine and Rehabilitation, Bağcılar Training and Research Hospital, İstanbul, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Ozkaya
authors.affiliation: Department of Physical Medicine and Rehabilitation, İstanbul University Cerrahpaşa Medical Faculty, İstanbul, Turkey.
authors.forename: Safak Sahir
authors.initials: SS
authors.lastname: Karamehmetoğlu
keywords: Bone mineral density; electromyography; muscle training; sclerostin; tonic vibration reflex