Contrast therapy

Contrast therapy is the practice of moving back and forth between hot and cold exposure within a single session rather than doing either one on its own. A typical approach spends a few minutes in heat, such as a sauna or hot shower, then switches to a much shorter stint in cold water or a cool shower, and repeats that cycle a handful of times. Some people finish on cold for alertness, others finish on heat to wind down before bed.

The reasoning behind it is straightforward, heat causes blood vessels to widen while cold causes them to narrow, so alternating between the two is thought to act like a pump that moves blood and fluid through tired muscles more than either temperature alone. It does not require special equipment, an ordinary hot and cold shower can work, though a home sauna paired with a cold plunge makes the temperature swing more pronounced.

A sensible starting protocol is a few minutes of heat followed by about a minute of cold, repeated three or four times, since jumping straight to long cold exposure can be uncomfortable and counterproductive. As with cold water immersion on its own, anyone with heart problems, high blood pressure or circulation issues should get medical advice before trying contrast therapy, and easing in slowly is safer than starting with the most intense version you can find.