On the second session of the second day of doubling up, I noticed a gawdawful ammonia smell. Like seriously... cat pee strength ammonia. It took me several minutes to realize:
OMG~ It's coming from me!! I'm sweating ammonia!
I looked around on the intertoobs when I got home and showered. It seems it's not so uncommon for some folk with protein heavy diets and is a natural result of the rapid breakdown of proteins during extreme workouts. I'm pretty confident that I'm eating enough calories to build muscle, which makes the odor incidental to my diet if I don't make changes in that area. An apple an hour before the final workout seemed to make quite a difference but I could still smell the fumes. I stay very well hydrated; I don't have any symptoms of kidney issues.
Any personal trainer or fitness buffs want to weigh in - is there anything else I should consider?