I’ve said this before, but inflammation is a necessary response to injury . It’s the inflammatory response that increases blood and lymphatic flow to and from the injured tissues, bringing healing nutrients and inflammatory mediators and removing damaged refuse. It’s the inflammatory response that makes injuries hurt, which prevents us from using and re-injuring the injured area. And yeah, the inflammatory response can get out of hand and do more damage than the initial insult, but it’s ultimately how our bodies heal damaged tissues and recover from injuries. If we didn’t have an inflammatory response, we’d never get anywhere. This was the crux of a very interesting blog post  by Kelly Starrett in which he questioned the typical use of ice after injury. In short, Kelly says that putting ice on a healing tissue is counterproductive because it halts or at least disrupts inflammation, which is really how we heal.
Do we want to use ice in order to reduce the inflammation incurred after a soft tissue injury?
Let’s establish what we mean by “inflammation” after an injury. We’re really talking about the inflammatory process, which includes pro-inflammatory and anti-inflammatory processes. It begins with the release of inflammatory mediators that cause vasodilation, or widening of the bood vessels, at the injury site. This allows more blood to arrive, and with it leukocytes and macrophages (types of white blood cells) to clean up the site and moderate the inflammation. More fluid at the site also means swelling, or edema, which, along with the increased sensitivity to pain, restricts movement and allows the inflammatory process to progress. But once that fluid is filled with waste products from cellular cleanup, it needs to be drained. That’s where the lymphatic system comes in. The lesser-known circulatory system, the lymphatic system removes all the waste products and excess fluid buildup caused by the inflammatory process. When the waste fluid is drained, healing can commence.
Since the lymphatic system doesn’t have a big multi-valved muscle in the center of the chest controlling the flow of fluid through its vessels, we need to get the lymph draining smoothly through other means, like elevating, compressing, or moving the tissue. What about icing? Kelly and his guest in that video above say that icing an injury promotes fluid build-up and restricts lymphatic flow. To reduce swelling, they like compression over icing, because the former doesn’t affect the lymphatic flow in a negative way.
How do these claims play out?
Icing a specific areas definitely disrupts the overall inflammatory process , lowering both inflammatory and anti-inflammatory cytokines. Icing muscles after a sprint workout, for instance, seemed to reduce levels of IGF-1 (an anabolic marker that usually increases after injury/exercise and improves healing/recovery), IL-1ra (an anti-inflammatory cytokine), and IL-1β (an inflammatory cytokine) while increasing levels of IGFBP-1 (a catabolic marker that breaks down tissue). Those are just markers, though, and an ankle sprain is not a sprint  workout. But still – the responses to exercise and injury are based on the same inflammatory and anti-inflammatory mediators. If one’s affected, the other likely is, too.
As for lymph flow, it’s been shown (albeit in a reference I can’t fully access ) that prolonged application of ice to tissue enhances the lymphatic vessels’ permeability, causing “backflow” of waste fluid back into the injured area , worsening edema, and potentially extending healing time.
So, is that that? Icing is bad?
Not so fast. With some injuries, it’s been shown to help. Clinicians are actually using cold therapy to induce hypothermia  and reduce brain injury and mortality while improving the outcome in patients who’ve just had a stroke. Or after something like pelvic surgery (which is a traumatic controlled injury of sorts), cold therapy can improve erection function and reduce incontinence . Following “primary injury” (the stroke) the application of cold is preventing “secondary injury” (brain damage) to the surrounding tissues originally uninvolved in the initial injury. Though this secondary injury phenomenon also exists with soft tissue injuries , and ice therapy seems to work in its prevention, the window of opportunity for intervention is pretty small – perhaps just the first thirty minutes  after the initial trauma.
Icing your ankle right after a really bad sprain to prevent secondary injury seems to make sense, but does it help with swelling and overall healing?
A 2004 literature review  on the ability of cryotherapy to affect soft tissue injury healing looked at 22 eligible randomized controlled studies to determine if ice was actually helping, and the results were mixed at best:
- Ice alone was better for pain after knee surgery when compared to no ice, but swelling and range of motion were not affected.
- Ice was no more effective than rehab in reducing swelling, pain, and range of motion.
- Ice and compression were better than ice alone at pain reduction.
- Of eight studies that compared the two, there was little difference between ice and compression and compression alone.
They conclude that “based on the available evidence, cryotherapy seems to be effective in decreasing pain,” but evidence is scant for any further conclusions. Another review using many of the same studies had similar findings , noting that the vast majority of the available studies purporting to examine the effect of cryotherapy on soft tissue injury employ surgery patients with open injuries. The authors stress the need for more research using patients with closed soft tissue injuries – sprains, strains – rather than surgery patients.
And that’s the big problem: there simply isn’t a lot of real, hard research on how icing affects the types of commonplace injuries people actually get. And why would there be? “Everyone knows” that you ice a sprained ankle. That’s just what you do. What’s there to study? Thus, most of the research on “soft tissue injury” either preemptively accepts icing as efficacious or uses surgery patients with open soft tissue injuries when what we should really be looking at are people with ligament, tendon, and muscle strains and sprains.
One thing to consider is that ice is rarely used in isolation. RICE, the acronym that everyone seems to follow after an injury, stands for “rest, ice, compression, elevation.” It’s the standard advice you’ll hear from most PTs and docs: rest the affected area, apply ice, compress it, and elevate the tissue. Thus, many studies that seem to show efficacy for cryotherapy also use compression, making it difficult to disentangle the two. Is it the ice or the compression, or the combo of both doing the work?
Indeed, some evidence suggests that compression is key. I was unable to find many studies that compared compression alone, icing alone, and doing nothing, but there are several studies showing major benefit for compression and icing over icing alone. Most recently , subjects recovering from recent ACL surgery received either icing or compression+icing. The compression+icing group had better pain relief and a marked reduction in pain medication usage when compared to the icing group. However, an earlier meta-analysis  found that while cryotherapy after ACL surgery seemed to help with pain, it did not improve range of motion or drainage. In other words, it was good for pain but did nothing to actually speed the healing process or get patients back to action. And in the one study  I did find that isolated compression and icing, compression bested both types of icing – continuous cryotherapy and intermittent ice pack application – in the reduction of post-foot-or-ankle-injury swelling.
The problem with RICE, as I see it, isn’t that icing is in there, it’s that people focus way too much on the icing and do it way to the exclusion of compression, while totally misinterpreting the rest and elevation recommendations. You’re not supposed to stay completely immobile and sedentary with your iced leg up on the couch for weeks while watching bad TV. After the initial downtime, you need to move! As soon as you’re able to move without pain, you should be mobilizing  the affected tissue. Don’t go hiking  on a broken leg or swollen ankle or anything, but don’t assume inactivity is best. Keep your movements  pain free and unloaded to begin with. Rotate that sprained ankle. Flex and extend that hurt elbow. And so on. If you’re going to ice, keep it short and sweet and immediately after the initial injury. Err on the side of moderation. Most studies indicate that the coldest temperatures are less effective at reducing swelling and may even increase it, while the “cooler” temperatures were better at reducing swelling.
So, to answer the initial question: it depends.
Clearly, people aren’t losing limbs and whittling away their connective tissue despite the prevalence of icing after injury, so I don’t think the situation is that dire. It goes both ways, of course; people aren’t going to turn into shattered husks of their former athletic selves just because they neglected to ice an injury or two.
Ultimately, I don’t think icing is as unequivocally detrimental to the healing process. It can certainly reduce pain and, if that’s the only way for you to get the tissues moving, that’s a good thing (as long as you don’t move too much too fast and end up re-injuring the weakened tissue). And it can likely prevent secondary tissue damage, particularly if you apply it shortly after an acute injury. But the extended, constant, day-in day-out cryotherapy that some of us feel is absolutely necessary anytime a tissue feels less than perfect? No. It seems clear to me that compression and mobilization of the injured area are likely more important and effective than ice.
I don’t want anyone to subject themselves to a laboratory limb contusion or anything, but I’d be real curious as to how you Primal folks handle your injuries. Do you ice them? Do you let the inflammatory cards fall as they may, confident that the composition of your tissue fatty acids will provide a suitable inflammatory response?
Let us know how it’s been working out for you in the comment section! If there are any physical therapists or coaches out there, I’d be particularly interested in your take on this.