Cooling Induces Motor Facilitation With Sympathetic Activation
Condition: Cryotherapy Effect
Study type: Interventional

Summary: 
      Cryotherapy has beneficial effects such as motor facilitation, increase isometric force
      generation, and reduce spasticity.

      It is known that the muscle spindle has sympathetic innervation. Muscle spindle sensitivity
      increase with sympathetic activity. This research has three hypotheses: First, short-term
      cold application to the skin increases sympathetic activity. Second, there is an increase in
      muscle spindle sensitivity with increased sympathetic activity. Third, the effect of
      short-term cold on muscle spindle sensitivity continues until the skin temperature returns to
      normal. The purpose of this research is to test these hypotheses.
    

Detailed description: 
      Cryotherapy is a frequently used treatment method in sports medicine and rehabilitation due
      to its beneficial neuromuscular effects. Its main beneficial effects are motor facilitation,
      increase isometric force generation, and reduce spasticity. The motor effects of cryotherapy
      may differ depending on the duration of application, the coolant used agent (ice, ice water,
      coolant spray, etc.), and the thickness of the subcutaneous adipose tissue. The short-term
      cold application increases the force of contraction with motor facilitation. As the cold
      application period gets longer, the effects of the cold that inhibit motor functions such as
      gamma motor neuron inhibition, muscle spindle inhibition, and muscle conduction block come to
      the fore.

      It is known that the muscle spindle has sympathetic innervation. It has been reported in
      recent studies that mental arithmetic, cold application to the skin, isometric contraction of
      remote muscles, and ischemia increase muscle spindle sensitivity through increased
      sympathetic activity. However, there are very limited studies showing that cold application
      increases muscle spindle sensitivity through increased sympathetic activity. On the other
      hand, in terms of determining treatment and rehabilitation strategies, it is important to
      know how long the effect of the cold application on muscle spindle sensitivity continues.
      However, it is not clear how long the effect of the cold application on muscle spindle
      sensitivity lasts after the cold application ends. There is a widespread belief that the
      motor facilitation effect of cryotherapy can occur with the stimulation of cutaneous cold
      receptors. Considering this view, it can be thought that the effect of the short-term cold
      application on muscle spindle sensitivity continues until the skin temperature returns to
      normal. This research has three hypotheses: First, short-term cold application to the skin
      increases sympathetic activity. Second, there is an increase in muscle spindle sensitivity
      with increased sympathetic activity. Third, the effect of short-term cold on muscle spindle
      sensitivity continues until the skin temperature returns to normal. The purpose of this
      research is to test these hypotheses.
    

Intervention name(s): Brief skin cooling
Intervention type(s): Other
Intervention description(s): Brief skin cooling will be applied to the hand using the cold-bath immersion
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: muscle spindle; sympathetic outflow; motor facilitation