[9530jh9054ven]

That doesn't seem to check. For his colleagues to be able to make a casual linkage between lowered cognition, tiredness, and irritability to him exercising, they must have observed said symptoms enough times and confirmed it with him more then twice in his life.

[DANmode]

The body is a mechanical filtration device.

If you are mostly sedentary, consume any form of what are toxins to a human (there's lot of kinds, don't get caught up on the buzzword), and then one day start working them all back out into your bloodstream at once, it makes sense to temporarily feel like garbage.