This is a very science-y book by a Danish author with a PhD in metabolism studies who is researching the effects of cold-water swimming. And when she says cold, she means cold—there are lots of (beautiful) photos of people dunking in slushy water and holes carved into the ice. While the definition of cold water could be anything under 15C/59F, she mostly seems to be writing about water temperatures of 5C/41F and below, which is far colder than anything I’ve been in (my coldest so far is about 8C/46F and I don’t have any particular desire to go colder).

Nonetheless, cold is cold, and I was interested in her explanations of what’s happening in your body when you submerge yourself in frigid liquid. I can’t say I understood it all, but I feel like I got the gist of what physical systems kick into action, what you can do to acclimatize to cold water, and how all of this may or may not be mentally and physically beneficial.

That “may or may not” is key here, because much of this book is (scientifically based) speculation; there are a lot of instances of “maybe,” “possibly,” and “this requires more research.” The truth is that it’s not really clear exactly how or even whether cold water can help any number of conditions; there’s tons of anecdotal evidence, but the hard scientific evidence is lacking. I’m personally wary of anything being promoted as a panacea, which cold-water swimming often is—not necessarily in this book, though it walks a fine line, I think. I was also suprised to find some long-debunked myths repeated here, like the notion that you lose 80 percent of your body heat through your head (you really don’t!). I didn’t expect that here.

That aside, there are some nice takeaways, and it was an intriguing insight into a different cold-water swimming culture—one that involves much colder water and many more saunas than we usually have here in England!

Further reading…