To have your swim across the English Channel officially recorded by the Channel Swimming Association, you have to jump through a number of hoops long before the actual 21-mile crossing: passing a medical exam, picking a date with appropriate tides, booking a boat pilot to accompany you. Pilots on the official list are currently taking reservations three years out. You also need to complete a verified six-hour swim in water temperatures of 60 degrees Fahrenheit or less—which, as it happens, is right around the recommended temperature range for post-exercise ice baths.
In a recent issue of the International Journal of Sports Physiology and Performance, French researchers tested swimmers at a Channel Swim Camp in Brittany, where attendees were attempting to tick off their six-hour swims. Unfortunately for the swimmers, water temperatures were around 55 degrees Fahrenheit. A total of 14 swimmers agreed to swallow ingestible thermometers to measure their core temperature during and after the swim, offering some sobering insights into what happens during—and, of particular interest to the scientists, after—prolonged…
