Health,  Science,  Wellbeing

A new way of thinking about ice packs for sore muscles

By Roberta Attanasio

We all know ice packs—many of us reach for them soon after an injury to reduce pain or inflammation. Think of strained muscles, sprained ankles, and so on. But is this the right approach to accelerate healing?

A 2019 article from The Washington Post states: “Today, ice packs have become as ubiquitous as aspirin—they’re a fixture in every athletic training facility and sold in drugstores throughout the country. Cold baths and ice tubs have also become one of sport’s most popular recovery aids. Nearly every high school, college and pro trainer’s room has at least one ice tub, and over the last 10 or 15 years they’ve become an essential post-workout or injury ritual for athletes in every sport.”

However, the article goes on to cite Gabe Mirkin, who decades ago helped popularize its use. Mirkin said that there’s no question that icing can reduce pain at least temporarily, but it comes at a cost. “Anything that reduces your immune response will also delay muscle healing. The message is that the cytokines of inflammation are blocked by icing—that’s been shown in several studies.” Instead of promoting the process of healing and recovery, icing might actually impair it.

Indeed, research in animal models from the past few years show the detrimental effects of icing on muscle regeneration following injury. But despite what we know, ice packs continue to be extremely popular.

Check inside the freezers or coolers at most gyms, locker rooms or athletes’ kitchens and you will find ice packs. Nearly as common as water bottles, they are routinely strapped onto aching limbs after grueling exercise or possible injuries. The rationale for the chilling is obvious. Ice numbs the affected area, dulling pain, and keeps swelling and inflammation at bay, which many athletes believe helps their aching muscles heal more rapidly.”

Now, results from a study (published March 25, 2021) may help, once again, to re-evaluate the very popular icing habits. The study, carried out in mice, shows that icing blunts the efficiency of muscle regeneration by perturbing the molecular environment within the injured tissues. So what happens exactly? Icing slows down the inflammatory process.

Inflammation is the body’s initial response to any infection or injury or infection—it is indeed the first line of defense of our immune system. It involves the coordinated action of a variety of pro-inflammatory cells and molecular mediators that all together fight off invading microbes and clean up bits and pieces of damaged tissue and cellular debris. The inflammatory response is then dampened by the anti-inflammatory process, which uses other cells and mediators to rebuild new healthy tissue.  

The researchers compared the inflammatory process occurring in damaged tissue that was treated with ice to the inflammatory process occurring in damaged tissue that was not treated with ice. They found that, in absence of ice treatment, active pro-inflammatory cells rapidly reached the injured tissue. Notably, in only a few days, most of the damaged muscle fibers had been removed. Then, proinflammatory cells, along with specialized muscle cells that rebuild tissue, reached the initially damaged muscle. After two weeks, the muscle was completely healed.

In contrast, these processes were noticeably delayed in iced muscles and, after two weeks, the researchers still found signs of tissue damage.

Inflammation is accompanied by four characteristics and unpleasant signs—pain, swelling, redness and heat. Most people use ice to reduce these signs. Without being aware of it, they might slow down healthy inflammatory responses, thus prolonging the presence of pain and other signs.

Takamitsu Arakawa, senior author of the study, told The New York Times: “Damaged, aching muscles know how to heal themselves and our best response is to chill out and leave the ice packs in the cooler.”

One Comment

  • Amanda

    Great article!

    It completely makes sense that by icing sore muscles and slowing down the immune response, muscle recovery occurs slower than wanted. I noticed the article only mentions ice packs and I’m not sure if that has a different effect than water immersion recovery, but one article I found from 2020 claims there is no benefit or hinderance of recovery when using water baths for recovery.

    This study attempted 4 types of recovery baths and compared them to only active recovery. The baths tested were cold water, neutral water, and contrast water (alternating between hot and cold water). The researchers used biomarkers MCP-1, myoglobin, and hs-CRP in addition to monitoring white blood cell (leukocyte) concentrations to assess recovery. They found white blood cell concentrations were unchanged between immersion therapies. MCP-1, myoglobin, and hs-CRP levels were also unchanged between the therapies. Overall, compared to active recovery only, there were no significant differences to support stating immersion therapy improves or hinders muscle recovery post exercise.

    It seems that this is an extremely interesting idea considering almost every athlete I know does this. When attending physical therapy, every session was ended with icing. Icing seems to go hand in hand with exercise. It seems to me that if it does in fact hinder recovery, it is something the health and fitness industry should seriously look into. For now, it seems like it is still up in the air.

    The study used: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674333/

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