The Truth Behind the Hot and Cold Compress Debate
The Low Down on the Heat vs Ice Debate
Heat or Ice? Which Should I Apply to an Injury?
When it comes to pain relief most of us are familiar with using heat or ice. Sprain and ankle? Apply an ice pack. Back sore from doing yard work all day? Lie on the heating pack. While you may have heard clear cut instructions on when to use heat and when to use ice, the real answers actually lie a bit more in the gray area. To gain some clarity on this topic, keep reading as we sort through the heat versus cold therapy debate. In this article when we reference heat we are talking about superficial heat which includes things such as hot packs or heating pads while cold therapy typically refers to ice packs.
WHAT EFFECT DO HEAT AND ICE HAVE ON THE BODY
It seems appropriate to kick off this inquiry with a deeper look at the physiological effect that hot and cold have when applied to the body. Afterall, the reason we apply these modalities in the first place is because we hope they will have a healing impact on the body.
When an injury occurs, tissue damage and inflammation typically follows. Pain, tenderness to palpation, sometimes bruising and difficulty moving or bearing weight through the injured body part can result. On a molecular level recovery from an injury involves tissue destruction, repair and then remodeling of connective tissue, muscle tissue, and blood vessels.
When ice or cold therapy is applied to an injured tissue, the cooling effect reduces swelling and slows the arrival of inflammatory mediators. It is also thought to reduce tissue metabolism and secondary tissue damage while also having an anesthetic effect that reduces pain (Swenson et al.,1996, Malanga et al., 2014). Heat or thermotherapy warms the skin and underlying tissues and has a vasodilating effect which brings more blood to the area and may promote healing by bringing more nutrients and oxygen to the injured area. It also has a pain-mediating effect and increases the elasticity of connective tissue (Malanga et al., 2014).
WHAT DOES THE EVIDENCE TELL US?
While we understand the physiological mechanisms of applying heat and ice, many of the recommendations we have about when to use each modality are based on anecdotal evidence. In 2015 Petrofsky et al. specifically examined the use of heat and ice to manage post-exercise muscle soreness and damage. They found that cold therapy immediately or 24 hours after exercise was more beneficial in reducing soreness than heat but wasn’t better than heat to mediate muscle damage. In 2014 Malanga et al., did a literature review of a large number of individual studies and reviews evaluating the effectiveness of heat and ice to treat acute musculoskeletal injuries and delayed onset muscle soreness. Their review found that many of the studies were of poor quality and found conflicting evidence in some cases. They concluded, however, that ice was more effective to treat acute injury with inflammation and heat for muscular pain and soreness and joint pain and stiffness.
As you can see the research is still somewhat unclear about the benefits of using heat versus ice in some scenarios. Typically individuals with joint pain and stiffness such as those with osteoarthritis prefer to use heat to manage their symptoms. If you have sustained an acute injury, especially if there is inflammation, using heat would not be recommended as it can worsen the inflammation. For muscle soreness after exercise or activity the literature is mixed and it's probably effective to use either modality based on your preference or experience in the past.
WHAT ABOUT USING ICE ON ACUTE INJURIES?
As mentioned above, it’s probably not wise to apply heat to an acute injury as the vasodilative effect can worsen inflammation. More recently, however, researchers and rehab professionals have been questioning whether using ice to stop the inflammatory process in an acute injury is actually helpful or harmful (Zi-Ru Wang and Guo-Xin Ni, 2021). The RICE approach to acute injury (Rest, Ice, Compression, Elevation) has been standard practice for quite some time but has recently come into question for quite a few reasons. The conventional wisdom of using ice immediately after injury is one of these reasons as we consider whether inflammation after acute injury is the big bad wolf we always made it out to be.
The inflammatory response actually serves an important role in injury recovery. Inflammation is the process of flooding the injured area with fluids containing white blood and other cells whose jobs it is to destroy bacteria and eat up dead and dying cells. This step is needed before tissue repair can begin. So if we think about inflammation as the first step to injury repair then it stands to reason that we should think twice about interfering with this process as it actually delays recovery.
For now we need more high quality studies to fully understand how and when cold therapy should be used with acute injuries. When injuries are severe and swelling is a limiting factor for recovery then ice or cold therapy is still likely a smart option to get control of inflammation so rehabilitation can progress. If the injury is mild or moderate, shortening the duration or frequency of applying ice may be something you want to consider so the body’s natural healing process can proceed.
BOTH ICE AND HEAT SHOULD BE USED WITH CAUTION
While the aim of both heat and cold therapy is to heal injured or painful tissues, when used incorrectly both of these modalities can cause injury. Here are some precautions and contraindications for each therapy (Seidel et al., 2021, Malanga et al., 2014). These lists are not exhaustive so you should always check with your doctor if you are unsure if these treatments are safe for you:
Cold Therapy
Frostbite, skin burns and neuropathy of superficial nerves can occur if ice or cold therapy is applied for too long
It should be used with caution in those with hypertension, mental or cognitive impairment, or decreased sensation
It should not be used in those with cold hypersensitivity, cold intolerance, Raynaud’s disease or over areas of vascular compromise or open wounds,
It can cause short term changes in joint position sense, muscle strength and neuromuscular control post-cooling
Heat Therapy
When used incorrectly and without proper protection heat therapy can cause skin burns or ulcerations
It is contraindicated in those with peripheral vascular disease, bleeding disorders, local malignancy, acute inflammation or trauma, edema, infection, open wounds, over large scars, those with impaired sensation (neuropathy) or impaired ability to communicate/cognitive impairments
It should be used with caution in those with diabetes and multiple sclerosis
THERE IS MORE WORK TO BE DONE
While there is still more work for scientists and researchers to do to settle the debate between heat and ice once and for all we hope you found some clarity after reading this article. Using heat and ice to manage pain or inflammation can be helpful in the early stages of injury recovery or exacerbation but don’t forget that active recovery is one of the best tools to promote healing and the physical therapists at Evolve are here to walk you through that process.
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