Great read.

But he's painting with a too broad brush. In other words, some people experience those symptoms, others don't. For instance, my fellow swimmer Brenden Sullivan swam in Tahoe at 38º F (well below 50) and didn't experience the can't-breathe symptoms).

Few people in the open water swim club that experience the loss of breath: most people get in the water & start swimming without problems. I do experience the loss of breath when the water temperature drops below 52º F:. In fact, I have to do backstroke for the first 50 yards before my breath normalizes. But I'm the only one I know who suffers like that.

Also, body fat makes a big difference, but muscle, not as much. I've seen too many body builders shiver in the sauna after swimming in the Bay. Body fat makes a big difference; big-time open water swimmers are not svelte.