Heat Therapy Vs. Cold Therapy
Which Should you Use?
Sprain an ankle? Pull a muscle? Feeling stiff and achy? Heat therapy and cold therapy are two easy and readily available methods to self treat an injury, but which one should you use?Both heat and cold therapies are relatively safe, cheap and easy to perform. They both provide modest relief from pain and inflammation.
A word on inflammation:
Inflammation is a natural process by which our bodies protect and heal themselves. In certain cases (laceration), inflammation is essential to close a wound and prevent an infection. In other cases (tendinitis), inflammation may run “rampant” and also affect healthy tissues. Heat and Cold therapies do not prevent inflammation, but merely affect the symptoms of inflammation.
Below is a short guide to both Hot and Cold therapies followed by a lengthy explanation of the physiology for those of you that are interested in more detail.
Cold therapy in a nutshell: (Sharp, Stabbing, Sudden pain) Use ice and compression immediately following an injury (the sooner the better) to reduce pain. Ice can be beneficial for the first 24-48 hours following an injury for pain relief (sharp, stabbing, burning), after that it provides little benefit. Chronic overuse injuries (tendinitis, rotator cuff injury) can be iced multiple times throughout the day to manage pain.
Application: The most effective application I’ve come across is to ice an injury until it is numb (less than 3 minutes with raw ice, 10-15 min with gel pack), and repeat once the tissues warm up again, as often as needed. Research has shown little benefit to ice beyond pain control.
Heat therapy in a nutshell: (Stiff, Achy, Muscle pain) Use heat therapy on injured tissues only after the acute stage has subsided (48 hours post injury) or if the nature of the injury is muscular/arthritic. Heat should be applied for 20 minutes at a time with at least an hour between applications. Contrary to popular belief, dry heat is more effective at deep penetration than moist heat. Heat should be avoided by people with infections, circulatory issues, or cancers. Heat may aggravate inflamed tissues and make the pain more intense, which is why it is not recommended with a fresh sprain. Research shows heat therapy is slightly more beneficial due to it’s “relaxation” properties that helps tissues lengthen and release “knots”.
Application: Full body heat (sauna, hot tub) is great for non-specific or arthritic joints but shouldn’t be used more than 30 minutes to prevent body temp spikes. Local heating (microwavable heat packs, bean bags) target specific areas and are more easily accessible, use them for 10-20 minutes over an area and get movement into those tissues before reapplying (45-60 minutes).
More in-depth look at Hot Vs. Cold:
Cold Therapy in depth: Cold therapy aims to reduce the metabolic rate of the tissue it is applied to by constricting blood vessels and numbing pain fibers, superficially (close to the skin). The decreased blood flow leads to less nutrient and gas exchange, slowing down metabolic processes. When an injury occurs, damaged tissue releases chemicals into the body to trigger inflammation and pain sensation. Inflammation is how the body responds to prevent further damage (pain with use) and repair (red, swollen). This is where ice can be most useful to numb pain. The cold will NOT penetrate deep enough to prevent inflammation, but will decrease the sensitivity of pain receptors in the area.
One should also take into account something called the Hunting Response. When cold is applied for long periods, there is a sustained constriction to local blood vessels. After ten minutes or so, there is a reactive dilation of the blood vessels and the whole process repeats, this cycle is known as the Hunting response and may limit the effectiveness of cold therapy when used for prolonged periods. Of the limited research available on cold therapy, there is little evidence to suggest ice is effective beyond pain control but little to suggest it isn’t doing something else at the cellular level. Combining ice and compression was found to be the most effective at limiting functional loss and decreasing recovery time, although not by much.
Heat Therapy in depth: Heat therapy effectively increases the metabolic rate of an area of tissue by dilating the blood vessels as it penetrates the skin. The increased blood flow brings in more oxygen/nutrients, loosens collagen, and helps clear waste products. Heat therapy is most effective for arthritis or soft tissue injuries. These types of injuries carry along the “stiffness, achy, tight” feelings that have progressed over days to weeks. Heat is also great for helping along an injury after the acute stage has passed and you move towards rehabilitation. Following an injury, the first 24-48 hours should focus on rest, compression, and cold therapy. Once the pain begins to subside, heat can be introduced to help the body “clean up” what’s left and regain function. Prior to exercise, heat therapy will loosen muscle tension and increase blood flow, potentially reducing the risk of injury. The research into heat therapy has found a correlation with lower disability and faster recovery times over the span of five days compared to controls (the largest study was for low back pain). This same study found less efficacy for using cold therapy in the same protocol. Local heating will not penetrate more than a few cm below the surface of the skin, so deeper muscles may not get as much benefit.
For Delayed-Onset Muscle Soreness (DOMS), heat therapy tends to be more effective at providing relief compared to cold. There were two studies looking at cold therapy for DOMS; one found it to be effective, one didn’t (I didn’t read the studies). For the most part, DOMS is unstoppable, the most effective method of relieving it is to move.