Petrofsky, J.S., et al. 2015. Cold vs. heat after exercise—Is there a clear winner for muscle soreness. Journal of Strength and Conditioning Research, 29 (11), 3245–52.
Intense exercise—or simply pushing ourselves much harder than usual—often causes delayed-onset muscle soreness (DOMS), which typically starts about a day after exertion and peaks on the third day postexercise (see Figure 1 for DOMS characteristics). People have used heat and cold to treat muscle soreness for over a thousand years (Petrofsky et al. 2015), yet to this day we still aren’t sure of the best way to minimize DOMS.
Petrofsky and colleagues revisited this question with a well-designed experimental study that offers intriguing insights on using heat or cold to treat DOMS.
Hot/Cold Treatments for DOMS
To minimize swelling and muscle pain, cold is traditionally applied via ice massage, cold packs or cold-water hydrotherapy (Petrofsky et al. 2015). Scientists have not determined the optimal amount and duration of cold therapy.
Heat treatments for muscle soreness include hot packs, diathermy (high-
frequency electric current to generate deep heat), ultrasound (sound waves to generate deep heat) and warm-water hydrotherapy. Petrofsky and colleagues say heat therapy relieves muscle soreness because extra heat enhances muscle tissue metabolism, leading to faster recovery. Heat therapy tends to make the muscle soreness less painful as well.
This study recruited 100 healthy, nonsmoking men and women (aged 20–29; BMI <40 kg/m2), who were randomly assigned to one of five groups:
- control (no treatment)
- cold packs immediately after exercise
- cold packs 24 hours after exercise
- heat wraps immediately after exercise
- heat wraps 24 hours after exercise
For cold therapy, cold packs were centered over the belly of the quadriceps muscle of each leg for 20 minutes. For heat therapy, low-heating wraps were applied to the quadriceps muscle of each leg for 8 hours. Note, with this type of heat therapy the heat is only 105.8 degrees Fahrenheit, and the heat wrap
is worn for 8–12 hours. The advantage is that it provides deep heat by being left on so long.
The authors highlight that standard clinical practice therapy guidelines were followed. The participants did not participate in any sports-like activities, had no previous training in squats and did not take drugs that would interfere with a muscle soreness assessment.
Inducing and Measuring DOMS
Researchers used three supervised rounds of squats to produce DOMS in the study participants. Each bout lasted 5 minutes, with a squat every 3 seconds. Soreness was assessed before exercise and 1, 2 and 3 days after exercise.
The assessments helped determine how the DOMS regimen affected maximal extension and flexion muscle strength of the knee (measured in a seated position) over a range of 90–125 degrees of motion. Additionally, each participant subjectively evaluated his or her soreness/pain on a scale from zero to 10 (zero for pain-free through 10 for “very, very sore”). This visual analog scale allowed a subjective assessment of muscle soreness, a factor that could not be directly measured.
The researchers also measured blood myoglobin, an objective biomarker for muscle soreness.
The control group, which received no therapy after the squats, showed a 23.8% drop in muscular strength on the day after exercise. The immediate heat and cold groups showed a much smaller 4.5% drop in strength. When therapy was applied 24 hours after exercise, cold did slightly better than heat.
As we might expect, the visual analog scale revealed that the control group felt the most pain, showing that (from a subjective viewpoint) no intervention is the worst way to treat DOMS. The two immediate therapies elicited the lowest pain ratings (with cold slightly outperforming heat). There was no significant difference in the heat and cold groups 24 hours after exercise.
Heat and cold applied immediately after exercise did the best job of minimizing loss of muscle myoglobin. The immediate-heat group saw the most improvement in myoglobin.
Overall, this research suggests that both immediate and 24-hour cold and heat help to prevent muscle soreness. For reducing pain, cold therapy performs better than heat, whether applied immediately after exercise or 24 hours later, according to the visual analog scale. For personal trainers, this may be the most telling message: Clients will have the lowest perceived soreness if they immediately apply cold packs to the target area for 20 minutes. Plus, it’s relatively easy for clients to do.