Heat Therapy For Muscle Relaxation 

Introduction

The process of thermotherapy, often known as heat therapy, entails applying light heat on injured or damaged areas of the body.  Heat therapy application on these injured areas changes the tissue's temperature, so as a result, the tissues become more extensible. Not only do patients claim to feel less pain, they also claim quicker recovery.  This results from the heat applied causing vasodilation in the area, increasing blood flow and thus, enhancing blood circulation. The extensibility and metabolic rates of the tissues therefore rise. The targeted tissues recover quickly. The surroundings remain unaffected by the heat.¹

Vasodilatation causes increased blood flow in response to an increase in temperature in the skin or soft tissue. Heat promotes the rate of catabolism, improves the uptake of oxygen, speeds up tissue repair, and activates enzymes like collagenase.²

Purpose

The objective of thermotherapy is to gradually change the tissue temperature in a specific area to trigger a particular biological reaction. Most thermotherapies are developed to target a specific tissue volume while causing the least amount of damage to neighbouring or surrounding tissues.²

Types

Moist heat: this heat comes from steaming towels, hot baths, and moist heating packs. When compared to dry heat therapy, the application of moist heat for treatment is far more successful because it produces relief in a shorter amount of time.

Dry heat: Dry heat sources such as heating pads, infrared lights, saunas, and dry heating packs can all be used to provide therapeutic heat. Depending on the severity of the condition, heat therapy can be used on a particular area of the body or the entire body. Saunas and hot water baths are examples of treatments that use heat to treat the full body. Athletes typically need this kind of heat therapy after sporting events have concluded.⁵

The selection of heat therapy is primarily a question of taste. For example, when body fat exceeds 25% of body weight, moist heat is generally more beneficial. The best product or service may be found through trial and error and experimentation with the wide range of possibilities accessible.¹

Mechanism of action

The sympathetic nervous system comprises two branches that regulate skin blood flow: the cholinergic active vasodilator system and the noradrenergic vasoconstrictor system. Major components of thermoregulatory responses across the majority of the human body are influenced by these dual sympathetic neural control mechanisms.

Falling core and skin temperatures during hypothermia cause reflexive increases in sympathetic active vasoconstrictor nerve activity, which lowers skin blood flow and preserves body heat. Increasing core and skin temperatures under heat stress trigger reflexive increases in sympathetic active vasodilator nerve activity, which in turn increases skin blood flow.

Heat-sensitive calcium channels mediate the impact of heat on pain. These channels increase intracellular calcium in response to heat.

Action potentials are produced as a result, stimulating sensory nerves more intensely and making the brain feel hot.

Previous research has indicated that the interchange of Ca²⁺ and Na⁺ ions in brain cells may be influenced by temperature. The application of cooling has been shown to raise pain tolerance (PTO) as well as pain threshold (PTH). Vasodilation is the consequence of the release of chemical mediators like prostaglandins and histamine when the temperature of the surface tissue rises. Since other physiologic and metabolic factors have a major influence on skeletal muscle blood flow, these vasodilatory mechanisms do not significantly affect skeletal muscle blood flow. The best way to improve blood flow to skeletal muscle is to exercise.

Preparations and safety measures

Patients can take the following easy measures to get ready for this therapy:

• Find out from the physiotherapist if you can resume using your regular prescription drugs
• Cut back on fluids on the day of the procedure
• Avoid alcoholic and caffeinated drinks two days before the surgery
• On the day of treatment, have light meals for breakfast or lunch
• Arrive one hour early for the operation and take some time to unwind
• Bring a friend or family member to help with transportation after treatment.⁶

Application technique

Hot packs, steam baths or rooms, saunas, heat wraps, towels, and sunshine can all be used to heat the superficial tissues. Electrotherapy, which uses infrared radiation, shockwaves, and ultrasound,  allow heat to be generated in the deeper tissues.

Exercise in warm water, known as hydrotherapy, aqua therapy, or balneotherapy, is a popular and successful treatment that helps a lot of individuals who suffer from excruciating musculoskeletal or neurologic disorders. By affecting thermal receptors and mechanoreceptors, the temperature of the water may inhibit nociception and affect spinal segmental processes. It has an anti-inflammatory action and promotes the homeostasis of the cutaneous barrier.

Warmth may also improve blood flow and ease tense muscles. Through the reduction of peripheral oedema and the attenuation of sympathetic nervous system activity, the hydrostatic impact may also alleviate pain.²

Risk

These are some risks to be aware of:

• "Warm" temperatures should be used during heat therapy rather than "hot" ones. You risk burning your skin when using temperatures that are too hot.
• There's a danger that using heat therapy when you’re ill could increase the likelihood of the spread of infection. 
• It is not recommended to apply heat directly to a small region, such as using heating packs, for longer than 20 minutes at a time. If you notice any increase in swelling, discontinue the therapy immediately. Make an appointment with your doctor if, after a week, heat therapy hasn't helped reduce any pain or discomfort or if the pain worsens.³

Precautions

Although heat therapy works well to relieve pain, heating pads can be hazardous if not used correctly. Here are some safety guidelines to prevent harm.

• Avoid directly placing a warm gel pack or pad against your skin. To prevent burns, wrap it in a towel before putting it on your skin
• Don't use a heating pad to sleep
• Use a heating pad on its lowest setting at first, then gradually raise the heat intensity
• Use of a heating pad with a damaged or fractured electrical cord is not advised
• Avoid using a heating pad on skin that is injured³

Indication

• Thermal therapy may help individuals with osteoarthritis of the knee. Additionally, it lessens oedema and enhances muscle performance.
• Rheumatoid arthritis (RA): Aids in the restoration of joint function and strength.
• Stress-related Patients: Those suffering from hyperthermia may benefit from thermal therapy. Additionally, it can assist in calming the body after stressful occurrences.
• Chronic back pain: Thermal therapy is beneficial for those with chronic back pain. The circulatory nerves surrounding the injured tissues are triggered by the heat. Higher blood flow to the back facilitates quicker recovery from illnesses.
• Tennis elbow: The patient experiences significant injury to their elbows as a result of prolonged wear and strain. For the greatest amount of pain relief, physiotherapists recommend combining heat and cold therapy for these individuals.

Contraindications

• A patient experiencing serious soft tissue injuries 
• A patient exhibiting significant skin bruising or oedema
• Patients with dermatitis
• Patients with multiple sclerosis (MS)
• Individuals with diabetes
• People suffering from Deep Vein Thrombosis (DVT)
• Individuals suffering from circulatory disorders⁶

Post-treatment care

The therapist may advise against using the heat for longer than fifteen to twenty minutes. For five minutes, the heat-affected region needs to be covered with a cloth. It is imperative that the patient adheres to the doctor's advice and does not stop the heat therapy suddenly. The area that has received heat therapy cannot be doused with water thereafter. If there is any discomfort, it needs to be reported to a physician.

Depending on their health, patients require different amounts of time to recuperate. Depending on the ailment being treated with heat therapy, the patient's recovery from chronic pain often takes 20 to 30 minutes. Sometimes the relief doesn't start to take effect for almost an hour.‎

Summary

In conclusion, heat therapy stands as a valuable modality for muscle relaxation and pain relief. Through the application of heat, physiological responses such as vasodilation occur, leading to increased blood flow to the affected area, which in turn promotes tissue oxygenation and nutrient delivery while aiding in the removal of metabolic waste products. Additionally, heat therapy can help alleviate muscle stiffness by decreasing muscle spasm and improving tissue elasticity, ultimately enhancing range of motion and flexibility.

Furthermore, the analgesic effects of heat therapy can provide significant relief from muscle soreness and discomfort. By stimulating sensory receptors and inhibiting pain transmission, heat therapy effectively reduces the perception of pain, offering both immediate and long-term benefits for individuals seeking relief from muscular tension and discomfort.

It is important to note, however, that while heat therapy offers numerous advantages, it may not be suitable for all individuals or conditions. Caution should be exercised in cases of acute inflammation, open wounds, or impaired circulation, as heat application could potentially exacerbate these conditions.

Overall, when employed judiciously and following best practices, heat therapy serves as a safe, accessible, and effective modality for promoting muscle relaxation and enhancing overall well-being.