Lately I've been doing hot-cold contrast bathing. The reason: to train the weak autonomic nervous system of a modern office worker.
This post describes how I do it and what it does for me.
Method
Why do people who are good at their jobs love saunas? I'm following what I remember from that book.
The core is repeating heat stimulus → cold stimulus → rest.
- Heat stimulus Sit in the sauna. I check my pulse and stay until my heart rate goes up a bit. That's roughly 3 minutes, and then I get out.
- Cold stimulus Stay in a cold plunge at 18 degrees Celsius or below for about 30 seconds, then get out. This is the most painful part. So at first, even holding out for just 5 seconds is fine. By the way, most public bathhouses don't really have a cold pool at around 18 degrees.
- Rest Simply lie down on a bed and let your heart rate settle. About 4 minutes.
At first, do just 1 set, and add more sets as you get used to it. I'm currently doing 3 sets.
Effects
- As I said, it trains the autonomic nervous system. Since you're forcibly alternating tension and relaxation, it trains switching between the sympathetic and parasympathetic nervous systems. There's no solid evidence for this.
- It feels like my mind gets reset. It could be the usual effect of a cold shower. Or maybe my body is just startled by the cold water.
- You get used to cold water. This feeling is better than you'd expect. Once you're used to cold water, you don't always need to shower with hot water. It feels like I'm getting stronger. The effect shows up fairly quickly.