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.”