Ice and heat are treatment options that are commonly used in the setting of orthopedic injuries to promote healing and reduce pain. However, plenty of confusion and misinformation exist regarding their effects on the body and their role in recovery. The truth is that science tells us there are considerations for each.
Effects on the Body
Ice and heat differ in their physiological effects. Ice is a vasoconstrictor – it narrows nearby blood vessels and causes a temporary decrease in blood flow. Heat is a vasodilator – it expands nearby blood vessels and promotes blood flow to superficial tissues. Below is a table that summarizes some additional effects of each.
A common denominator between the two is pain; both modalities serve as effective analgesics, or pain relievers, and can help reduce pain in the short term.
Effects on Inflammation
As shown above, heat increases blood flow to the site of application and can increase edema formation; therefore, it is not advisable to use heat in the acute phase of an injury, as it may temporarily increase inflammation.
Ice is a bit more controversial in this regard. Ice can decrease capillary permeability, which means that it reduces movement of fluid from our capillaries to nearby tissues. While this may prevent future swelling from occurring, this does not reduce already-existing swelling at the targeted body part. Reducing current swelling levels can be achieved in three ways: pharmacologically (NSAIDS, etc.), compression, or elevation of the injured body part.
When Should I Use Them and For How Long?
Now that we know the differences between the two – when should you use them?
Because of heat therapy’s ability to reduce joint stiffness as well as increase collagen extensibility, you could use heat prior to initiating exercise with the aim of preparing local tissues for increased metabolic demand.
The use of ice is typically viewed in the context of following an injury. Research suggests that ice is most effective at reducing secondary tissue damage during the acute phase, or within hours of the onset of injury. Outside of the 24 hours following an injury, its effects are greatly reduced.
Now – for how long?
In short: you can achieve the desired physiological effects of both modalities in ~10-20 minutes.
A common suggestion you may he heard before regarding ice is “20 minutes on, 20 minutes off;” however, this adage isn’t necessarily true. No research exists to suggest that the desired effects of ice or heat are additive in nature. So, 20 minutes on, 20 minutes off for consecutive sessions is unlikely to provide you with any greater physiological benefit beyond the initial application. Also, several hours of use per day can keeps you sedentary, and less overall movement has a greater influence on tissue healing and recovery.
What Role Does All This Play in the Healing Process?
The effects of ice and heat on the healing process are not as significant as we once thought. Research suggests that these modalities he no significant ability to speed up tissue healing or improve clinical outcomes.
In summary:
Ice and heat are both cheap, simple, and safe analgesics – or pain relievers. Ice may assist with minimizing secondary tissue damage if used promptly (within hours) after injury; however, results are mixed. You should apply heat or ice for ~10-20 minutes at a time. No research suggests that the proposed benefits of these options are cumulative (i.e. using ice for longer periods of time does not mean you’re getting rid of more swelling) Neither ice nor heat significantly impacts the healing process or recovery time – for better or for worse!Article authored by Jaden Gillette, PT, DPT
Jaden Gillette, PT, DPT