Should I hit the hot tub after a treatment?

This is one of the questions that we as therapists will constantly be asked, and for good reason too. Should I apply heat after an injury or ice? And what is actually happening when I apply a heat pack and how long should I keep it on for?

Well firstly, research has shown that levels of the stress hormone cortisol will drop after a relaxing soak in the tub. So if nothing else, it will have the effect of making you feel better and less stressed for that time! But what is happening physiologically? Applying heat causes the blood vessels to dilate allowing more blood to flow into the area. With a chronic injury where the muscle can be tight and surrounded by scar tissue this is perfect. The heat will help soften and loosen the muscles around the injury allowing them to move more freely. This would have a negative effect with an acute injury, a sprain or a bruise for example. So in this case the traditional advice is to apply cold. Cold constricts your blood vessels to limit swelling, which is helpful in the early stages. Research shows that applying cold for roughly 8 minutes is optimal for this response. If you are familiar with people like Wim Hof – ‘the ice man’ – you will have heard of the benefits of daily exposure to the cold and that is a subject for another time!

There is also, well supported, research for the use of heat immediately before exercise. A 2005 study found that pre-heating calf muscles with a heat pack allowed for greater ankle flexion. The heat pack in this scenario was applied for 15 minutes and towels between the pack and the skin ensured that it didn’t exceed “comfortably warm” levels. If we think of the muscles as a spring, and we want to get as much power from that spring before using it we would be ill advised to stretch it out like an accordion. Running it under a hot tap would create the effect that we would be looking for. Look what squash players do with the ball before a game to get it to move quicker right away.

Overall, the clinical evidence on the use of heat suggests a few guidelines. Use it before exercise rather than after, and don’t use it on a fresh injury. So should you hit the hot tub the evening after a treatment? If you can, why not, but be sure to drink water as you’re in the tub, preferably out of a tap and not the tub! Yuk!