Cold Plunge or Hot Pack: Hype or Helpful?
One of the most common questions and commonly used treatments for musculoskeletal health and recovery is the use of thermal modalities. Thermal modalities can include both hot and cold treatments and can range from heat packs, ice baths, cold plunges, etc. Use of these modalities are typically geared towards recovery, inflammation, performance adaptation, and mental health. What does heat and cold therapy actually do? Are different versions of cold therapy all the same in terms of results? Are there any contraindications? How does the evidence compare to the hype? First let’s define a few things:
Cold therapy, also known as cryotherapy, can include ice massage, ice packs, whirlpools, and cryotherapy devices.
Heat therapy, also known as thermotherapy, can include hot packs, paraffin baths, dry heat therapy, hydrotherapy, ultrasonography, microwave diathermy, and infrared radiation.
Delayed-onset muscle soreness (DOMS), is a type of ultra structural muscle injury, a result of eccentric (lengthening under contraction) muscle contractions or unfamiliar exercises. DOMS typically starts somewhere between 6 to 12 hours postexercise and can peak between 48 and 72 hours postexercise. DOMS will eventually subside after 5 to 7 days.
Now that we understand the two therapies and what we are typically trying to improve when applying them, let’s dive deeper into each:
The underlying principle behind heat therapy is to basically increase blood flow to the area, reduce any muscle stiffness, increase range of motion, enhance tissue flexilibty, and to of course alleviate pain. This focus on recovery helps prevent future injuries by allowing you to continue to train earlier instead of training on damaged tissue (even if it is purposely damaged from training). Heat can be also defined by the mode of transfer. Conduction (direct), convection (air/water), or radiation via conversion all create heat used for therapeutic purposes. You can continue to classify depending on the depth of penetration of the heat. Typically you are looking at superficial heat or deep heat. Looking at heat this way, you can see how it is a very versatile tool when it comes to managing musculoskeletal injuries.
The use of cold therapy or cryotherapy in the past has been used more for acute musculoskeletal injuries or even fatigue. Cold water bathing has been used for thousands of years through many cultures, but recently it has become popular as a way for athletes to attenuate the negative effects of strenuous exercise on future performance. Cryotherapy reduced muscle soreness and improves functional recovery. Cryotherapy is thought to decrease muscle damage and DOMS caused by training. It is proposed that cold exposure helps to vasoconstrict vascular tissue, leading to reduced inflammation and tissue metabolism, decreased cardiac output, and of course analgesia (recused pain sensation). Other various neuromuscular and hormonal changes also come along with cryotherapy. However, overall the supporting evidence remains limited.
One of the major benefits though for cryotherapy is the decrease in muscle swelling after completing strenuous exercise.Reducing this muscle edema can help contribute to injury prevention by restoring some tissue foundation which improves joint stability. DOMS reduced allowing you to get back to training earlier. Cold therapy basically limits the stress response symptoms of exercise (primarily signs of fatigue and restoring function to the muscle groups). There is also a quicker recovery of muscle strength after resistance training.
Although often the focus is often on the benefits when discussing these modalities, there are some risks. Cryotherapy can lead to decreased muscle oxygen saturation as a result of the vasoconstriction or narrowing of blood vessels. This may lead to muscle impairment and increased risk of injury if prolonged. Timing is also important, as cryotherapy can lead to reduced power output. Cryotherapy should not be used before training or activity/performance. There is also not enough evidence to say what is superior to what when discussing these modalities including cryotherapy.
Deciding which thermal modality to implement is dependant on the circumstance of the individual. Although heat and cold offer different results, they do both modulate blood flow, reduce muscle spasm, and offer a pain reduction effect (even if the mechanisms of action are different physiologically). For cold therapy, the mechanism of action for pain relief is a numbing effect to the area, thus reducing the sensation of pain. Hot therapy on the other hand offers a reduction in muscle tension, therefore reducing the discomfort associated with muscle injury. Muscle spasm is also associated with both hot and cold therapy. Cold therapy reduces muscle spasm through diminished nerve activity. Heat, on the other hand does through by dilating blood vessels, counteracting the spasm with relaxation. Both therapies also address inflammation by controlling blood flow. Cold therapy reduces inflammation through its vasconstrictive effects where heat helps inflammation through vasodilation, clearing out inflammatory byproducts from the injured area, allowing for more oxygen and nutrients involved in the healing process to be delivered to the area.
Cyrotherapy is often suggested or prescribed earlier on in an injury (during the acute phase). The goals earlier on may be reducing swelling, inflammation, or pain, which cold therapy addresses. It is thought that cold therapy allows for a faster recovery by minimizing tissue damage. Heat on the other hand, is often prescribed after that acute phase, once DOMS has subsided. Heat can counter act the muscle stiffness and tension, allowing for a smaller reduction in mobility due to DOMS.Think of heat as a tool with training, great before and great after as a recovery tool. Use ice sparingly and specifically early on in an injury to reduce further damage from swelling.
Overall, you can see how temperature can be a tool for both injuries and training sessions. Always check for skin irritation or damage when using both, especially extreme temperatures or prolonged direct skin contact. Always consult a licensed professional who can help diagnose and manage both injuries and training symptoms from an evidence-informed perspective, better yet from someone who has experience in your specific area of interest!
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