Why heat, then cold

Heat first, to slow down

Every KELD session moves from warm to cold. The sauna comes first: a Finnish-style sauna at 80 to 90°C, or a hot bath at 38 to 40°C if that is what you have. Eight to twelve minutes is enough. The breath gets longer, the shoulders drop, and the noise of the day starts to fade.

Sit on the lower bench at first, where it is cooler, and breathe slowly through the nose. Leave when you have had enough. The timer is a guide, and the body has the final say.

Then the cold, briefly

Cold water at 10 to 15°C is cold enough. A plunge, a lake or your coldest shower all work. The first few seconds bring a sharp gasp, which is a normal reflex. Your job is to answer it with a long, slow out-breath and stay where you are.

Thirty seconds is a good start. Over a few weeks most people build to one or two minutes. Staying calm while everything in you wants to get out is the practice. It is also the part people carry into the rest of their week.

Why the round ends in the cold

A full session runs two or three rounds of heat and cold, then five minutes sitting still somewhere warm. Most people describe this last part as the clearest they feel all day: awake, quiet and warm from the inside.

Research into contrast bathing is still developing, and many studies are small. So we talk about how it feels and how to do it safely, and leave the bigger promises to others.

How it fits into a week

In the Contrast program you do three or four of these sessions a week, with two short lifting days between them. Each session takes 45 to 55 minutes, including the sitting at the end.

Check with your doctor before you start if you have a heart condition, high blood pressure, or take medication that affects either. Never take a cold plunge alone.