Shallow water blackout. It actually happens frequently enough in this exact circumstance, trying to lap the pool completely underwater, that there are PSAs specifically addressing it: https://www.youtube.com/watch?v=u_Mb7uictG4
In this case, he doesn't seem like a very strong swimmer so was probably completely gassed out, and the slight blood pressure drop from going vertical caused him to faint.
Shallow water blackout. It actually happens frequently enough in this exact circumstance, trying to lap the pool completely underwater, that there are PSAs specifically addressing it: https://www.youtube.com/watch?v=u_Mb7uictG4
In this case, he doesn't seem like a very strong swimmer so was probably completely gassed out, and the slight blood pressure drop from going vertical caused him to faint.
Yikes. TIL - hyperventilating can lower your CO2 and mostly CO2 triggers your desire to breathe.
So when you run out of oxygen- you don’t feel the need to breathe. Just pass out.