Sometimes when I’m running a little too hard for a little too long, I’ll feel sick to my stomach. A few times in high school, and a number of times in the Army, I’ve seen people run until they puke. Why exactly does this happen? I know, it’s because out-of-shape people are exercising too hard, but what exactly is going on in the body when this happens? I notice the only time I start to feel sick to my stomach when I run is when I’m starting to breathe really hard–some connection there?
On a related note, what’s up with those stitches people get in their sides when running? I usually only get them in my right side–is that normal?
Thanks in advance. 
i believe the stitches are due to strain. specifically, strain to the ligaments which hold your liver in place. the liver is so damn big that when you run, it jostles up and down a bunch. double plus is you’re a heavy drinker.
as to the nausea, i wish i knew.
jb
Fairly certain that stitches aren’t strain, but rather are anerobic metabalism (or something similar, it’s been a while ).
I too would like to know the hard exercise=puking business.
Could the puking be mild dehydration?
Well the fact that yopu are concuming all the ready sugar in your body and draining your body’s resources of oxygen account for the light-headedness.
As to the nausea: I think it is just from making the stuff in your stomache bounce up and down so much. People who are not used to exercising, have weak stomache mucles or have a large amount of matter in their bellies when they go jogging are more likely to feel this way.
IMHO of course