When thermal therapy is applied to the area, it causes vasodilation (widening of the blood vessels) increasing blood flow to the area. This brings more inflammatory factors (cells responsible for healing), nutrients and oxygen to be able to improve the cells' functions.
Reducing Muscle Contractures
Thermal therapy reduces contractures by increasing the nerve firing initially due to the nerves sensing the temperature change. Then the relaxation of the components in the muscle (Golgi tendon organs and muscle spindles). This causes the muscle to relax because the nerves are not telling the muscle to contract any more.
Thermal therapy works by a theory called the pain gate theory by increasing the speed at which the nerves send non-painful messages to the brain which stops the brain from receiving the painful nerve message.
Improving Range of Motion
Heat allows the muscles to relax, reducing the likelihood of it restricting the joint’s flexion and extension. Synovial fluid, which is the lubricating fluid within the joint, becomes less thick and more liquid-like. This works like oiling a door hinge, allowing the joint to have smoother movement. Please see the range of motion page for explaining how the things stated improves/maintains range of motion.
More Efficient Warm up
Due to applying an external heat source it allows the substance that coats the individual muscle cells to become more liquid. As a result, it enables better lubrication of the cells allowing them to slide more efficiently. This is particularly beneficial for ridden horses. When a horse is ridden cold (without heat applied to their back first) it is harder for the horse to lengthen their back initially. This causes them to invert their spines known as a dipped back (postural lordosis). Having a rider on before before warmup also adds to the challenge, as they have to work harder to counteract the rider’s weight. Having applied heat prior to ridden work, it allows the spinal muscles to lengthen reducing the risk of muscle knots and tightness occurring. This helps gives you your proper outline with engaged core muscles! Please use this information under the advice of a fully qualified veterinary professional.