What causes nausea during a workout? This happens especially when I work my legs.
The sight of a fat girl in spandex doing stiff legged deads in front of you?
The shunting of blood away from the GI tract (which the body does not consider “vital”), to both a)vital organs (heart, lungs and brain) and b)the muscle being pushed.
You hear of so much puking with legs because you are utilizing the largest muscle groups we have.
Hope this helps!
The huge rise in lactic acid levels. Try a SMALL amount of baking soda before your leg workout. 
To my knowledge this happens when the clearance of the lactic acid in your system doesn’t happen fast enough resulting in nausea. It usually happens when using high reps and short rest times and can be avoided or at least minimized by taking longer rest between sets.
I think it has to do with low blood suger levels. Post workout nutrition will solve that in a matter of 10-15 min.
The change In the bodies PH balance from
an over production of lactic acid.
You don’t know what work out nausea is until you’ve tried the Meltdown I & II workouts! Keep a trash can near by!
Just a clarification:
The blood shunting and lactic acid production (in this case) are not “either/or” and both contribute to the problem of nausea. As a tissue becomes more relatively hypoxic (due to decreased blood flow) you will also see greater lactic acid production.(In addition to what you’re seeing produced just from the exercising itself).
Mufasa
Injesting baking soda has been shown to have absolutely no effct on lactic acid levels. The body compensates for the added base, and it’s compensatory actions are counter-productive to the workout. You may relieve acid indigestion, though!