I don't think I'm alone in my ever worsening "clickbait fatigue". "Dairy Causes Cancer!" (says one study. All the other studies disagree). "Diabetes Cured!" (In mice). "New Drug Cures Flu in 24 Hours!" (Maybe in a few years). The example we're discussing here is that "Icing Injuries Is Harmful!". The real answer is that it's not that simple.
(Quick note: feedback on this blog is that the academic research can be a little difficult to understand. If at any time while reading this you just want to get to the real world implications, feel free to skip to the last section for a summary.)
So on this topic, the first point to be made is that all the studies regarding ice having a negative effect on injury healing were done on mice or rats. That's where all these revelations are coming from. However, it is well understood in the scientific community that it cannot just be assumed that the same experiment would have the same result in humans as it does in mice. These studies are simply one of the first steps of experimental procedure. Once something is effective in mice, it is highlighted for further study. I don't mean to just dismiss these studies, as they are important. They just aren't as conclusive and life changing as the authors make it sound.
Here is a quick background on ice and injury. An acute injury will often involve some inflammation (a.k.a swelling) after the event, particulary in things such as muscle or ligament strains. Icing was historically used as a means of limiting this swelling a little bit. This was seen as desireable as some of the cells included in the inflammatory process are thought to literally increase the level of pain you experience, as a psycho-physiological means of getting your brain to protect this newly injured area. Swelling was even seen as harmful, which is not true. Inflammation is a helpful little process whereby the body is healing itself. It is the laying down of new tissue to replace the damaged, and if allowed to do so alongside other little behaviour changes, you will end up with a muscle or whatever structure back to it's full strength and ready for life as it used to be.
So, we've established why inflammation is not a bad thing. As a result, some healthcare professionals are moving to change our mindsets about two inflammatory control aspects of healthcare we have traditionally used. The first part is to avoid non steroidal anti-inflammatory medication (the most common being ibuprofen) in acute injury. This is true, especially when discussing broken bones. There is some evidence these medications may adversely affect the healing of the body by acting on inflammation at a cellular level.
The other new recommendation is to avoid icing. It is a controversial opinion which has even been shared by the british journal of sports medicine social media team. It's controversial because it instills fear. "You're doing it wrong." It's controversial because it's a little over-simplified and reminiscent of click bait, which obviously not a good thing in healthcare. So rather than just accepting that "ice is bad", I decided to see if there was any validity to the claim that icing an injury was harmful by looking at the papers cited as evidence, in detail.
Physiopedia, which is like wikipedia for physios, said this:
ice may potentially disrupt inflammation, angiogenesis and revascularisation
ice may potentially delay neutrophil and macrophage infiltration
ice may potentially increase immature myofibers
this can result in impaired tissue regeneration and redundant collagen synthesis
The British Journal for Sports Medicine, said this:
Even if mostly analgesic, ice could potentially disrupt inflammation, angiogenesis and revascularisation, delay neutrophil and macrophage infiltration as well as increase immature myofibres. This may lead to impaired tissue repair and redundant collagen synthesis.
You'll notice these excerpts are worded in almost exactly the same way. That's because both publications took their comments directly from the same study; Singh et al. 2017 - Effects of topical Icing on Inflammation, Angiogenesis, Revascularization and Myofiber Regeneration in Skeletal Muscle Following Contusion Injury.
Now here is exactly what Singh et al. said in the first paragraph of their closing section (marked "discussion" for anyone that's not used to reading scientific journals):
"These findings suggest that, although icing may mildly suppress inflammation and some aspects of angiogenesis/revascularization, these effects are not sufficient to retard muscle regeneration after contusion injury."
They went on to question whether frequently applying ice may exacerbate this effect and make it more meaningful in clinical outcome, as they only applied ice once, for 30 mins after the injury, Luckily, someone did this (3 x 30 min applications 2 hours apart) and said:
"In summary, clinical-like cryotherapy reduces the inflammatory process through the decrease of macrophage infiltration and the accumulation of the inflammatory key markers without influencing muscle injury area and extra cellular matrix remodeling." Ramos et al. 2016 -Cryotherapy Reduces Inflammatory Response Without Altering Muscle Regeneration Process and Extracellular Matrix Remodeling of Rat Muscle.
The study which Singh et al. feels needs more attention is Takagi et al. 2011 who reported smaller myofiber cross sectional area at 28 days post treatment in their experimental group. Admittedly this would be a concerning finding if it were bulletproof, but the fact is the Takagi and Singh experiments were similar apart from the fact that Singh clarified that the rats were in a cage and free to move around, while Takagi didn't. It may be that a lack of movement in the test subjects in Takagi's experiment was the reason for sub-optimal healing, rather than their icing protocol.
In human acute injury, ice has not been shown to have any consistent benefits, apart from the reduced use of medication for pain management. It has not been shown to cause any harm either. A different type of pain that has been studied with cold therapy is delayed onset muscle soreness, which everyone will have experienced after a hard gym session or the like. In these symptoms, cryotherapy may help speed up recovery.
So to summarise. Icing has not been shown to have any meaningful long term impact on recovery. However, there are three situations which I can see in which you may NOT want to use ice to manage swelling:
If you are concerned by the findings that ice may reduce the speed of healing in the short term.
If you feel more research is needed, but in the meantime would rather be cautious.
If you are planning on a rushed return to your goal activites (e.g. sport) in less than 28 days (which I would never recommend without a full physio assessment first).
In the other camp, these are the situations in which you may still want to use ice:
You have high pain levels/significant swelling, and want to avoid using anti-inflammatories, as recommended by current research.
You will abide by tissue healing timelines before return to full activities (which is about 6 weeks minimum, if rapid onset swelling and/or pain developed following your injury).
You feel the above criticisms of icing are tenuous, as they ignore the fact that in the long run, defined as 28 days post injury, icing did not have a meaningfully negative effect on healing.
My final word will be that if you do develop some swelling because of an injury, or even in a body part that you have previously injured or had long term problems with, make sure you see a healthcare professional. Usually swelling means something is happening or has happened that needs to be addressed, but these things are usually much easier to deal with if you address them early.
Be Well,
Mike.