Heat or Cold? What’s Best to Use After an Injury?
Heat or Cold? What’s Best to Use After an Injury?
To RICE or Not to RICE After an Injury
Most of us have been injured at one time or another, and more likely than not, the instruction we received was to “RICE” it: rest, ice, compress, and elevate the injured area. We do this because we’ve been told that it is the best response to help reduce pain and inflammation and to help the injury resolve more quickly.
But is this really the case? What is really happening in the body, and what does the research say?
The truth is that there is very little evidence examining the use of RICE post-injury, but the literature examining icing post-injury shows that this method may not be the best way of caring for injuries (Long et al, 2005, van den Bekerom et al, 2012).
What Happens After an Injury?
After an injury occurs, inflammatory chemicals are released from the injured tissue, causing blood to rush to the area, and with it white blood cells that begin cleaning up the injured tissue. This causes swelling and increased sensitivity to pain. Eventually, the waste gathered by the white blood cells will leave the area via the lymphatic system, at which time the swelling dissipates.
The swelling, stiffness, and pain should be considered a positive response. Although it may be frustrating, this response keeps us from further injuring the area and also helps to initiate healing.
The Use of Cold Post-Injury
Cryotherapy, as it is called when we use cold or ice, will initially (in the first 20 minutes post-injury) cause blood vessels in the area to constrict to a depth of 1-2 cm, blood to flow more slowly, and a reduction in the chemical mediators that cause blood vessel dilation (Long et al., 2005).
After about 30 minutes, however, homeostasis will take over, and blood flow will begin to return to normal again (Belanger, 2003).
There are still many questions that need answering however, such as: What drop in body temperature is therapeutic? Are 20 minutes enough to have a therapeutic effect?
These results seem to support using ice to prevent inflammation, at least for injuries that are fairly superficial (those close to the surface).
The big question is, do we really want to prevent inflammation and swelling?
One school of thought that has increasing evidence that inflammation (and with it, pain and swelling) is an evolved reaction by the body to prevent further injury and to kick-start the healing process. If this theory is correct, then our immediate reaction of icing an injury is actually detrimental to the healing process, since ice may restrict blood flow as well as slow lymphatic drainage.
The one effect of cryotherapy that has been well proven is temporary pain reduction via slowed nerve conduction velocity. Given this information, we then must decide whether reducing pain temporarily is worth the potential for slowed healing.
The Use of Heat Post-Injury
So what about heat? We often use a heat pack to help relax muscles but tend to avoid it immediately post-injury, likely because we don’t want to increase the inflammation. However, if what we’ve just learned is true, is this really correct?
Should we instead be using heat to promote inflammation, therefore speeding up the healing process?
In fact, there is some evidence that heat may speed healing by increasing circulation and blood flow, as well as increasing metabolic activity. Robertson et al. (2006) examined this hypothesis and found that there is an increase in circulation and metabolism, but, much like cryotherapy, it is primarily the superficial tissues that are affected.
In deeper tissues, blood flow and metabolism change very little. Because the body is so good at maintaining a constant tissue temperature in the muscles and organs (homeostasis), tissue temperature never gets high enough to have this effect for the deeper structures (Cameron, 2003).
Overall, it appears that there is little evidence that heat can truly speed healing, however, as with ice, the heat seems to work well in decreasing pain. This happens via the pain-gate theory. Interestingly, whether to use heat or cold for pain management seems to be individual. Some patients report that ice seems to work better, others prefer heat (Denegar et al., 2010).
Patients and clinicians alike often use contrast baths to repeatedly cause dilation and constriction of the blood vessels. The hope is that this will help both “pump” swelling out of an area, and also bring blood flow to an area.
So are either of these mechanisms true? Unfortunately, once again there is very little evidence that contrast baths decrease swelling, but if we assume that the above is correct, we may be able to have some effect on blood flow.
In truth, the mechanism that works best to “pump” swelling out of tissues is muscle contraction, as well as compression. Excess fluid in the tissues moves into the lymph system, and by moving and engaging muscles, this fluid is pushed back to the lymph nodes.
So What Should You Do After Injury?
Our bodies are generally well-adapted to dealing with an injury, and though we’d like to speed up healing, neither ice nor heat has great evidence for doing this. This doesn’t mean that either is useless however, both have been shown to do well for reducing pain, each via different mechanisms.
So what should we do after an injury?
- Protect the injured area.
- Let your body go through its inflammatory process.
- Manage your pain.
- Eventually, use movement and compression to decrease swelling.
As always, a physiotherapist can assess and advise you after you’ve had an injury.
Physiotherapists are highly trained healthcare professionals who help people recover from injury.
Book an appointment with one of Innovation Physical Therapy’s experienced physiotherapists by calling one of our 6 clinics located throughout Edmonton and Sherwood Park including Riverbend, Meadowlark, Belvedere, Namao, Sherwood Park or our newest clinic in West Henday.
Cameron, M. 2003, Physical Agents in Rehabilitation: From Research to Practice, 2nd ed, Saunders, St. Louis.
Denegar, C.R., Dougherty, D.R., Friedman, J.E., Schimizzi, M.E., Clark, J.E., Comstock, B.A., Kreamer, W.J. 2010, “Preference for heat, cold, or contrast in patients with knee osteoarthritis affects treatment response”, Clinical Interventions in Aging, vol. 5, pp. 199-206.
Long, B., Cordova, M., Brucker, J., Demchak, T. & Stone, M. 2005, “Exercise and quadriceps muscle cooling time”, Journal of Athletic Training, vol. 40, no. 4, pp. 260-263. Robertson, V., Ward, A., Low, J. & Reed, A. 2006, Electrotherapy Explained: Principles and Practice, 4th edn, Butterworh Heinemann Elsevier, Edinburgh.
van den Bekerom, M. P. J., Struijs, P. A. A., Blankevoort, L., Welling, L., van Dijk, C. N., & Kerkhoffs, G. M. M. J. (2012). What Is the Evidence for Rest, Ice, Compression, and Elevation Therapy in the Treatment of Ankle Sprains in Adults? Journal of Athletic Training, 47(4), 435–443.