Effect of Bone on Vibration-Induced Muscle Strength Gain
Condition: Bone Mass; Effects of Vibration
Study type: Interventional

Summary: 
      The aim of this study is to investigate whether there is a relation between bone mineral
      density of lower limbs exposed to vibration and the muscle strength gain in the knee
      extensors and flexors, and a relation serum sclerostin level and the muscle strength gain in
      the knee extensors and flexors in healthy young adult women.

      Forty healthy young adult women are planned to include in this study. The participants
      meeting the criteria were randomized into two groups: the training group (20 cases) and the
      Control group (20 cases).

      The whole-body vibration (WBV) training group will be trained on a WBV platform (Power Plate)
      5 times a week for 4 weeks period. Participants will be asked to stand upright on WBV
      platform. Training volume and training intensity will be low at the beginning but progressed
      slowly according to the overload principle. The training volume will be increased
      systematically over the 4-week training period. The training intensity will be increased by
      increasing the amplitude (2-4 mm) and the frequency (40 Hz) of the vibration. The subjects
      will be asked to report negative side effects or adverse reactions in their training diary.
      In the Control group, sham stimulus will be performed by WBV platform 5 times a week for a 4
      weeks period.

      Plasma sclerostin level and, the right and left knee flexor and extensor muscles strength
      will be measured before and after training period. Isokinetic torque will be measured with
      the Biodex (Biodex System 3 PRO Multijoint System Biodex Medical Inc. Shirley/NY
      USA)extremity-testing system. The right and left lower limbs bone mineral density (BMD) and
      muscle strength will be measured before training period. The BMD will be evaluated by bone
      densitometer (Norland XR-46 DXA, USA). Sclerostin levels will be measured by human sclerostin
      ELISA kit.

      The rest muscle electrical activity of right and left knee flexor and extensor muscles will
      be evaluated at pre-vibration, post- vibration and, during vibration. The rest muscle
      electrical activity will be measured by Powerlab (data acquisition system, ADInstruments,
      Australia) device.
    

Detailed description: 
      Vibration has a strong osteogenic effect. Vibration-induced bone formation is neuronally
      regulated. Vibration can also effectively enhance muscle strength and power. Previous studies
      have shown that vibration increases muscle electromyographic (EMG) activity. Attempts to
      explain vibration-induced increases in EMG activity were based on the tonic vibration reflex.
      Tonic vibration reflex activates the muscle spindles, thereby enhancing the excitatory drive
      reflex of the alpha motoneurons. On the contrary, it was shown that the vibration treatment
      did not enhance the muscle spindle sensitivity and led to presynaptic inhibition of muscle
      spindle group Ia afferents. As an alternative to tonic vibration reflex, the recently
      described bone myoregulation reflex has been suggested to potentially explain the increased
      muscle strength and electrical activity induced by vibration. Based on the bone myoregulation
      reflex, bone is sensitive to mechanical stimuli and can send mechanical input signals to
      central nervous system and so can neuronally regulate the muscle activity.

      The cyclic mechanical loading to the bone stimulates the osteocytes. According to bone
      myoregulation reflex, the more the osteocytes are stimulated by the cyclic mechanical
      loading, the increase occurring in the muscle strength and activity may be more. The rate of
      osteocytes stimulated by vibration may be determined with serum sclerostin level. Sclerostin,
      the protein product of the SOST gene, is an osteocyte-specific cysteine knot-secreted
      glycoprotein that is a potent inhibitor of bone formation. Sost/sclerostin levels have been
      reported to be reduced by mechanical stimulation.
    

Intervention name(s): whole-body vibration (WBV); WBV (Sham stimulation)
Intervention type(s): Device; Device
Intervention description(s): The whole-body vibration (WBV) training group will be trained on a WBV platform (Power Plate) 5 times a week for 4 weeks period. Training volume and training intensity will be low at the beginning but progressed slowly according to the overload principle. The training volume will be increased systematically over the 4-week training period. The training intensity will be increased by increasing the amplitude (2-4 mm) and the frequency (40 Hz) of the vibration.; Sham stimulus will be performed by WBV platform 5 times a week for a 4 weeks period.
Other intervention name(s): Cyclic mechanical loading
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Bone; Muscle strength; whole-body vibration