What is the hardest swim set you have ever done?

The toughest swim, which almost did me in, was a 50M fr split request in a 200M fr event.  The 50 went very good, taking maybe 2 breaths, however I had to legally finish the rest of the swim to get credit. I was ok at 100 but wasn’t recovering and started gasping. The seed time I thought was plenty slow enough (20 seconds slower than actual time) but I was the only one still swimming at 175M.  I rolled on my back at that point with feet sinking and loosing muscle control. It was a mental pursuit to avoid grabbing the lane line.  Finally finished with everyone waiting. 

The toughest swim, which almost did me in, was a 50M fr split request in a 200M fr event.  The 50 went very good, taking maybe 2 breaths, however I had to legally finish the rest of the swim to get credit. I was ok at 100 but wasn’t recovering and started gasping. The seed time I thought was plenty slow enough (20 seconds slower than actual time) but I was the only one still swimming at 175M.  I rolled on my back at that point with feet sinking and loosing muscle control. It was a mental pursuit to avoid grabbing the lane line.  Finally finished with everyone waiting. 

Oh man, it hurts to reading that!  I know exactly what you went through, because that happened to me on a 100 breaststroke race.  I hadn't yet been diagnosed with dysautonomia, so I didn't understand what was happening.  Adrenaline had over-flooded my system, and I lost muscle control like you did.  My body locked up on me about 10 yards before finishing.  Those were the hardest last 10 yards I have ever swum.

Exactly  
Good you have the dysauto under control now

That last 15m lasted about 30 seconds and the only thing that kept me from drowning was the split request