Effect of Radius on Alpha Motor Neuron Excitability
Condition: Osteoporosis
MeSH terms: Osteoporosis
Study type: Interventional

Summary: 
      This study hypothesize that radius subjecting to mechanical loading may affect excitability
      of alpha motor neuron innervating muscle, based on its bone mineral density. If this
      hypothesis is valid, it can be firstly suggested that the relationship between bone mineral
      density and muscle strength is bidirectional.

      A total of 80 voluntaries are planned to include in this study.

      After forearm vibration is applied, bone mineral density (BMD) and bone mineral content (BMC)
      will be measured in all cases. Alpha motor neuron excitability (H/M ratio, recruitment),
      background muscle activity will be evaluated by electromyography at pre-treatment,
      post-treatment and, during treatment in cases.

      Forearm vibration will be applied by forearm vibration device (FAV). FAV with mechanical
      loading will apply forearm. Cases will sit on armchair. Two intervals of FAV will be applied
      at a frequency of 45 Hz. Each interval will consist of 60 second of FAV followed by rest.

      The right radius BMD and BMC will be evaluated by bone densitometer (GE-LUNAR DPX PRO).

      Motor unite potentials at rest, Hoffman reflex, F response, M response will be measured by
      electromyography at right flexor carpi radialis. Medtronic Keypoint Portable 2 channel
      electromyography and Neurotrac ETS device will be used.
    

Detailed description: 
      It is usually reported that there is a parallelism between changes in the bone structure and
      function and the muscle structure and function. Sarcopenia is frequently observed in
      osteoporotic patients. Bone formation increases or bone resorption decreases with exercise.

      To date, the effect of bone on the muscle activity is not investigated. One of the most
      important functions of bone bear mechanical loads include body weight. Bone must be strong
      enough to resist the mechanical loading. Mechanisms need to protect bone when bone is subject
      to excessive mechanical loading. These mechanisms may mainly focus on strengthening the bone
      and/or changing vectorial properties of mechanical loading applied bone.

      The vectorial properties of mechanical loading applied bone may be controlled by muscle
      contractions. Bone contains wide mechanoreceptor net constructed by osteocytes.
      So,distribution of the mechanical loading on bone cross-sectional area is possible to
      perceive. It may be also possible that inappropriate distribution of mechanical loading on
      bone crosssectional area is optimized by muscle contractions. To get this regulation, there
      should be a mechanism that muscle activity is controlled by central nervous system based on
      mechanical loading distribution on bone cross-sectional area. We previously showed that bone
      can regulate muscle activity, based on its bone mineral density. According to this study
      result, it can be suggested there may exist a mechanism that bone sensing mechanical stimuli
      can send the signals to central nervous system and neuronally regulate muscle activity (bone
      myo-regulation reflex). (It is also well known that load-induced adaptive bone formation is
      neuronally regulated. Taken together, a general mechanism, bone reflex, may be defined that
      bone subjected to loading can neuronally regulate bone formation and muscle activity)

      This study hypothesize that radius subjecting to mechanical loading may affect excitability
      of alpha motor neuron innervating muscle, based on its bone mineral density.
    

Intervention name(s): Forearm vibration
Intervention type(s): Procedure
Intervention description(s): Mechanical loading with forearm vibration will be applied right radius in all groups.
Other intervention name(s): Cyclic mechanical loading
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: bone; motor neuron excitability; forearm vibration; Mechanical Loading