In the lake my arms had lost all memory of swimming, but in the safety of a pool they could recall what to do. I was in the water for about half an hour and swam 700m with brief rests. Even a few bilateral breathing lengths.
I was pleasantly surprised by my pace which dipped below 2:30min/100m. My impression is that I've lost endurance by forgetting how to manage with reduced respiratory gas exchange.
Let's hope I can move my shoulders tomorrow.