First we’ll consider cold therapy, technically known as cryotherapy. Researchers at the University of Kentucky reviewed 15 large scale studies containing over 300 college athletes. After periods of high level performance, a group of these athletes were given 5 minute, full body ice baths. They reported a 20% decrease in DOMS symptoms over their non-icing counterparts—quite a substantial finding.
For those of us unable (or unwilling) to take post-workout ice baths, what about using ice pack? As research would have it, these can be effective as well. Blood flow is certainly a sign of healthy muscle tissue, but too much isn’t necessarily a good thing. Elevated blood flow after an intense workout is an integral part of both inflammation and muscle soreness. Athletes who applied ice effectively reduced excessive blood flow by about 50% after icing for 10 minutes. This study didn’t ask specifically about muscle soreness, yet cryotherapy using ice packs almost certainly reduces symptoms.
So it would appear that cryotherapy does indeed help reduce the severity of muscle soreness. This being said, it’s important to note that icing does nothing to speed muscle recovery times. To date, rest, hydration, and proper nutrition are the only proven ways to accomplish this.
Upon examination, post-workout heat fared far worse than cold. Several large studies have shown that applying heat to muscles after a workout does nothing to prevent DOMS. While it may feel good, it doesn’t appear to help. On a slightly more positive note, one small study did demonstrate that heat may offer modest benefits to low back pain. This only applied to chronic, non-acute, mechanical back pain, and the relief reported was only mild to moderate.
But there’s more. As noted above, ice reduces excessive blood flow after exercise, reducing overall inflammation. Heat does the exact opposite. When applying heat incorrectly or for too long after an intense workout recovery times may be lengthened. Even so, many trainers tell their athletes that heat in the form of hot packs, saunas, and hot tubs can be helpful. When not used on acute injuries, they believe it loosens up tight muscles before and after workouts. Whether or not this is true has not been rigorously studied.
Further muddying the waters, current research has demonstrated that long-term use of cryotherapy can slow healing. While it will certainly contribute to sore muscles, inflammation is actually a central part of the healing process. To control inflammation to aggressively, as the thinking goes, is to inhibit the healing process.
So what does this mean for you? According to University of Kentucky trainer Joseph Ross, moderation is the key. “Does icing help? Absolutely. If you’ve got an acute injury, then it’s great. Just don’t ice the same joint every day, after every workout. Excessive icing may increase your chances of injury,” he says.
As for using heat after a workout? “I tell my athletes to take a hot shower and call it quits,” he says. “I have yet to see any real benefit to heat therapy. There’s no evidence to support it. Hot tubs are great for you and me, but won’t help an elite athlete after high intensity exercise. And never apply heat to an acute injury. This will do nothing but increase pain and inflammation.”
In conclusion, ice has been shown to both decrease muscle soreness and has a well-established role in treating acute injuries. Conversely, heat may take the edge off of chronic low back pain but may lengthen recovery times. What’s more, using it on a new injury isn’t advisable. Says Ross, “use common sense. Just keep heat off of an acute injury and you’ll be fine. And remember that muscle soreness is temporary. It may hurt a little, but will go away on its own with no help at all.”