Taking Control of My Cold Plunge Experience

I’ve been toying with leaving a negative Google review for the medical spa where I do my cold plunge.

Conceptually, the spa has it right: For appointments, you call them with the time you’d like to come in and the temperature you want. Their tub is really designed for home use, not a commercial setting, so the underpowered pump warms or cools the water at a rate of about one degree every 10 minutes. You save a ton of time having the spa sort all this out before you arrive.

In reality, during the six weeks I’ve been doing cold plunges, not once have I found the tub within three degrees of what I’ve asked for.

While I blame lazy staff for failing to make the temperature adjustments, the good news is that I’ve figured out shortcuts to save time. I’ve taught myself how to program their machine and I’ve learned a lot about the thermodynamics of water.

First, body heat warms water significantly in a small tub. As a result, if you want to spend several minutes in water at 45 degrees, you need to start with the temperature at about 43.5. You also need the machine to continue cooling the water while you’re in the tub — you can’t set it and forget it. My strategy at this point is to crank the chiller down to its lowest setting of 37 degrees and to climb in when the water falls to 43.0. I’m sure I’ll break the whole thing soon.

Second, if you want to maximize the benefits from cold — which is the point after all — you must move continually in the tub to break up the thermal layer around your skin. As a survival tactic, do the opposite: If you ever find yourself stuck up to your neck in chilly water, sit perfectly still with your hands on your thighs and you’ll be fine.

While I have probably found my low temperature limit, I am fascinated by cold plunge enthusiasts who push the physics of cold water. For starters, most chilling pumps have a bottom setting of 37 degrees, meant for experienced plungers and Navy Seals. For an even colder experience, you can pour straight ice into an insulated container and let it partially melt for a plunge just above freezing. Then there’s the special challenge for people who have a backyard cold plunge in wintry environments. On YouTube, you can see people clearing the snow off the lids of their tubs, and breaking up the ice that has sealed their tops shut. A padded lid can indeed keep the water above freezing for a time; eventually though you must add biodegradable antifreeze to keep the water liquid.

Here in Miami, I don’t worry about these kinds of problems. On 90-degree days with 90% humidity, a cold plunge is actually kind of refreshing. Nevertheless, I’m sure that when I’m walking home after a plunge, I look awfully strange. Very rarely in South Florida do you stroll past a person with bluish lips and chattering teeth.