Hot or cold? Exploring what works best after exercise

Ice baths have become a popular recovery strategy among elite athletes and gym-goers, used to reduce soreness and speed up recuperation after exercise. However, a recent study published in the Journal of Thermal Biology suggests that ice baths may not be the best recovery method after all. My colleagues and I compared ice baths against heat-based recovery methods, finding that recovery is more complex than simply cooling down.

Strenuous exercise can cause damage to our muscle fibers, particularly after eccentric exercises like downhill running or lowering weights. This damage triggers an inflammatory repair response, which includes increased sensitivity of pain receptors, contributing to muscle soreness. To study the effects of different recovery methods, we recruited 40 healthy adults and had them perform a specific exercise that caused muscle damage.

Participants were randomly assigned to one of four recovery methods: cold-water immersion (10°C), hot-water immersion (42°C), hot-air exposure (similar to a sauna), or passive recovery (sitting and doing nothing). After 72 hours, we found that none of the recovery methods significantly restored muscle strength faster than others.

However, hot-water immersion participants had higher levels of heat shock protein 72 (HSP72), which supports repair processes and protects cells during stress. Heat-based methods were also associated with more favorable changes in biological markers linked to muscle damage and inflammation. Cold-water immersion did not improve any recovery markers but was more effective at reducing perceptions of muscle soreness.

Our study suggests that recovery cannot be measured using a single outcome. Feeling less sore does not always mean being physiologically recovered. Cold-water immersion may be more beneficial for reducing muscle soreness, while heat-based recovery may be better for stimulating the biological processes that help muscles repair and adapt.