One of the most common things people do when they sprain an ankle, twist their knee, or undergo some other acute soft tissue injury is slap a bag of ice on there. If you ask them why they’re icing the injury, it’s to “stop inflammation and reduce swelling.”
Is this a good idea?
Although we tend to denigrate it, inflammation is a necessary response to injury: the inflammatory response increases blood and lymphatic flow to and from the injured tissues, bringing healing nutrients and inflammatory mediators and removing damaged refuse. The inflammatory response makes injuries hurt and swell up, 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, particularly if we have a poor baseline inflammatory status, 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.
If icing stops or impedes all that, this makes me question the ubiquitous advice to ice any and all soft tissue injuries.
What does icing injuries do?
To understand whether we should ice our injuries, we must first understand what icing does—specifically—to injured tissues and whether it impedes or aids healing and recovery.
Icing disrupts inflammation
Icing a specific areas definitely disrupts the overall inflammatory process, lowering both inflammatory and anti-inflammatory cytokines.1 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-1? (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.
Icing reduces pain
The most consistent effect of icing is pain reduction. Everyone agrees on that. Not everyone agrees whether it’s good or bad.
Icing slows blood flow to the tissue
Icing slows down blood flow to the site of the the injury.2 While icing proponents claim that adding and removing ice causes a rebound increase in blood flow, there’s not much evidence for it.3
Icing has differing effects on lymph flow
It’s been shown that prolonged application of ice to tissue enhances the lymphatic vessels’ permeability, causing “backflow” of waste fluid back into the injured area, worsening swelling, and potentially extending healing time.4 It’s also been shown that applying cold (1°C) water to the ankle for 30 minutes increases lymph flow at the ankle.5 Short term icing might increase lymph flow (and reduce swelling), while “prolonged” icing could have the opposite effect.
Icing has little to no effect on swelling
Icing by itself doesn’t seem to consistently reduce swelling.6 Combining cold with compression and movement, however, may reduce swelling, but is it the ice or the compression and movement? Prolonged icing at too low a temperature may even increase swelling (by increasing lymph backflow into the injured tissue).
Icing reduces “secondary injury” to tissues
Following “primary injury” (the acute trauma) the application of cold is said to prevent “secondary injury” to the surrounding tissues originally uninvolved in the initial injury. Ice or cold water application can slow the metabolic rate of the damaged tissues, lowering the risk of secondary injury. Though icing seems to work against secondary injury in soft tissue injuries, the window of opportunity for intervention is pretty small—perhaps just the first thirty minutes after the initial trauma, albeit in animals undergoing “crush injury” (which is exactly what it sounds like).78
Should we ice injuries?
As you can see, the effects of icing on injured tissues are a little confusing and appear to be contradictory.
It lowers blood flow, which should reduce swelling, but doesn’t really reduce swelling on its own according to research.
It can sometimes cause lymphatic backflow into the tissues, but it can also sometimes improve lymphatic drainage and flow.
It definitely reduces pain, though it’s unclear how helpful that is.
One unmitigated good is that icing right after the acute trauma can probably prevent or limit secondary injury to surrounding tissues.
What does the research say about actual results in humans? Does icing actually help healing and recovery of soft issue injuries? 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:9
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 icing on soft tissue injury employ surgery patients with open injuries.10 The authors stress the need for more research using patients with closed soft tissue injuries—sprains, strains—rather than surgery patients.
That’s not to say there isn’t any research in favor of icing:
There is an old study from the 70s that found a combination of compression and icing in the first 48 hours after an ankle sprain was superior to compression alone for recovery. The icing+compression group were back to full activity after 9 days, while the compression group took 14 days to recover.11
Another ankle sprain study found that in subjects with Grade 4 ankle sprains (very painful and serious), those who iced their injuries within 36 hours of the injury took about 14 days to recovery, compared to 30+ days for subjects who used ice or heat after 36 hours. That’s an enormous difference.12
A study out of Finland randomized a group of adults with soft tissue sports injuries to either a cold gel or a placebo gel. The cold gel group recovered more quickly and experienced less pain than the placebo group.13
What is icing good for?
Reduces pain: This can help an injured person get back to movement quicker. The more pain-free movement you can engage the injured tissue in, the faster you’ll recover and the better you’ll heal. Motion heals.
Reduces the risk of secondary tissue injury: Applied to the injured tissue right after the injury and up to 36 hours post injury, ice can reduce tissue temperature and metabolism enough to lower secondary tissue damage.
What is RICE?
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 icing injuries 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?
The problem with RICE, as I see it, isn’t the icing. It’s that people focus way too much on the icing, ignore the compression, and totally misinterpret 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.
They also forget about movement.
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. Start doing light bodyweight squats as soon as you knee can handle it. And so on. Movement is far more important than ice.
If you ice, how long should you ice an injury?
If you’re going to ice, keep it short and sweet and immediately after the initial injury. Ice injuries for 10-15 minutes every two hours for the first 24 hours, and that’s it. If it’s a really bad injury, you can extend that another 24 hours.
Colder isn’t always better. 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.
How I ice an injury
Imagine you sprain your ankle. It’s pretty painful. You can’t put too much weight on it, you’re limping heavily, there’s some swelling. What should you do?
Here’s what I do (leaving out any crazy devices or therapies):
Ice pack or cold (not ice water) water immersion for 10 minutes every 2-3 hours when awake, ASAP. I want to start as soon as possible after the injury. I don’t do it when I’m sleeping, of course.
After it comes out of the cold, I wrap it. Compression.
As long as it doesn’t hurt, I start rotating that ankle. I dorsiflex. I plantarflex. I do circles. As long as nothing hurts, I move that ankle. Motion is key.
I elevate. Not too high, but I keep it up off the ground.
24 hours later, I stop the cold but keep the compression and unloaded movement going.
When I can finally put weight on it, I walk. I make sure to walk as slowly as I need to avoid limping. Proper movement patterns are important to maintain. Walk normally no matter how slow you have to go.
That’s it. That’s how I use ice with acute injuries.
Ultimately, I don’t think icing is the most important part of acute injury recovery. 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 a very serious acute injury. But the extended, constant, day-in day-out icing 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 more important and effective than ice, and that kind of prolonged icing can even be detrimental.
How do 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.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.