Latency of Vibration-Induced Reflex Muscle Activity
Condition: Effects of Vibration
Study type: Interventional

Summary: 
      Whole Body Vibration (WBV) applies thrust force in opposite direction to gravity to body.This
      mechanical stimulation induces reflex muscular activity. Tonic vibration reflex (TVR) is most
      commonly cited mechanism to explain WBV-induced reflex muscular activity (WBV-IRMA), although
      there is no conclusive evidence that TVR occurs. The bone myoregulation reflex is another
      neurologic mechanism used to explain the effects of vibration on muscular performance.

      Investigators hypothesized that latency of WBV-IRMA is different from latency of TVR. Primary
      aim of this study is to determine latency of WBV-IRMA. Secondary aim is to investigate
      whether WBV-IRMA is explained with TVR.

      Twenty healthy young adult men are planned to include in this study. Participants will stand
      upright with their knees locked during WBV. PowerPlate Pro5 will be used for WBV. WBV with
      high amplitude at 25,30,35,40,45 and 50 Hz will be applied. Surface electrodes will be placed
      on both the soleus muscles. To measure TVR latency, piezo-electric accelerometer will be
      placed on the achilles tendon and this achilles tendon will be stimulated with spring based
      mechanical reflex hammer. Our pilot study was showed that motor unit potentials (MUAP)
      occurred in a 1:1 response with vibration. After confirmation of this finding, WBV-IRMA
      latency will be measured in the present study. To measure WBV-IRMA latency, piezo-electric
      force sensor will be placed between heel and WBV platform. Exact moment of initial strike of
      heel when thrust force expressed by WBV begin to be transferred to body will be determined.
      The time between moment of the initial strike and corresponding MUAP is defined as "WBV-IRMA
      latency". Piezo-electric stretch sensor will be placed between knee and malleol to simulate
      muscle spindle. The reflex muscle activity of soleus muscles will be measured by PowerLab
      (data acquisition system, ADInstruments, Australia) device.

      This project is planed to be completed in 1 months.
    

Detailed description: 
      Whole-body vibration (WBV), as a method of exercise training, is becoming increasingly
      popular in physical therapy, rehabilitation, and professional sports, and is increasingly
      used in beauty and wellness applications due to its beneficial effects on the
      neuromusculoskeletal system. These benefits include improved strength, power, flexibility,
      jump height, and balance. However, little is known about the physiological mechanisms
      underlying the effects of WBV on muscular performance, although the presence of reflex muscle
      activity during WBV has been shown. Tonic vibration reflex is the most commonly cited
      mechanism to explain the effects of WBV on muscular performance, although there is no
      conclusive evidence that TVR occurs. Studies have reported that direct vibration applied to a
      muscle or tendon stimulates muscle spindles, thereby causing a tonic vibration reflex to
      occur. As highlighted by these studies, muscle spindle discharges are sent to the spinal cord
      through Group Ia afferents during muscle or tendon vibration. There, they activate
      motoneurones that cause the muscle to contract. However, it has been reported that the
      sensitivity of the muscle spindle decreases or does not increase and that presynaptic
      inhibition occurs in Group Ia afferent fibers with vibration.

      The bone myoregulation reflex (BMR) is another neurologic mechanism used to explain the
      effects of vibration on muscular performance. BMR is a reflex mechanism in which osteocytes
      exposed to cyclic mechanical loading induce muscle activity. Osteocytes embedded in the bone
      matrix are interconnected by numerous dendritic processes, forming a wide, mechanosensitive
      cellular network. Osteocytes exposed to cyclic mechanical loading send mechanical input
      signals to the central nervous system, influencing the neuronal regulation of muscle
      activity.

      Investigators hypothesized that latency of WBV-IRMA is different from latency of TVR. Primary
      aim of this study is to determine latency of WBV-IRMA. Secondary aim is to investigate
      whether WBV-IRMA is explained with TVR.

      Twenty healthy young adult men are planned to include in this study. Participants will stand
      upright with their knees locked during WBV. PowerPlate Pro5 will be used for WBV. WBV with
      high amplitude at 25,30,35,40,45 and 50 Hz will be applied. Surface electrodes will be placed
      on both the soleus muscles. To measure TVR latency, piezo-electric accelerometer will be
      placed on the achilles tendon and this achilles tendon will be stimulated with spring based
      mechanical reflex hammer. Our pilot study was showed that motor unit potentials (MUAP)
      occurred in a 1:1 response with vibration. After confirmation of this finding, WBV-IRMA
      latency will be measured in the present study. To measure WBV-IRMA latency, piezo-electric
      force sensor will be placed between heel and WBV platform. Exact moment of initial strike of
      heel when thrust force expressed by WBV begin to be transferred to body will be determined.
      The time between moment of the initial strike and corresponding MUAP is defined as "WBV-IRMA
      latency". Piezo-electric stretch sensor will be placed between knee and malleol to simulate
      muscle spindle. The reflex muscle activity of soleus muscles will be measured by PowerLab
      (data acquisition system, ADInstruments, Australia) device.

      This project is planed to be completed in 1 months.
    

Intervention name(s): whole-body vibration (WBV)
Intervention type(s): Procedure
Intervention description(s): whole-body vibration (4 mm amplitude, 25,30,35,40,45,50 Hz)
Other intervention name(s): Cyclic mechanical loading
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: whole-body vibration; latency; reflex response; muscle