Why do I feel sick after exercise?

Why do some people vomit and defecate after strenuous exercise? Is there anything that can be done to stop this?
20 June 2013



I'd like to ask a question regarding a too intensive workout and a sometimes occurring sudden nausea during or afterwards. What makes this happen and what happens in the body? This thing happened to me when I began working out seriously about three years ago at the university. It never happened in the gym, but in intensive group exercise sessions, like cirquit training and boxercise. Back then I think it was about learning not to eat too much an hour or more before the exercise. However recently I felt nauseous and weak and I think this was just because of too much exercise, not eating wrong. The experience is quite strange, I feel dizzy, everything in my stomach attempts to get upwards and stuff in my gut starts to makes it's way down quickly - pardon the graphic description. Basically you need to think quickly where's the nearest loo, just in case.

So I'm interested what makes this happen, what kind of stress this is to the body and what the body gets from reacting this strongly?


David - I'm David Weston, a PhD student in neuroscience at the University of Cambridge. Feeling sick after exercise is something that most of us are pretty familiar with, especially if you exercise as infrequently as I do. But why does our body and our gastrointestinal system re-assert itself after a run around the block? Well, exercise is very physically demanding and your body reacts by increasing blood flow to your muscles and your heart and your lungs, and your brain to keep your body able to process energy and keep your muscles going. This diverts blood away from your visceral organs like your stomach and could deprive your gastrointestinal tract of the oxygen it requires to function. This symptom is called ischemia and is believed to be one of the reasons why you might feel sick after intense or prolonged exercise. Now, ischemia can in very severe cases damage the lining of your stomach and cause the bacteria in your stomach or the toxins that they produce to enter your bloodstream. So, some evidence also suggests that gastrointestinal distress is caused by what you eat and drink before exercise. One study found that foods with higher fat and protein content were linked with nausea and vomiting in triathlon runners. Other studies even suggests that taking aspirin before you exercise could increase your chance of gastrointestinal discomfort. Exercise also increases the levels of hormones released in the brain that control processes like thermoregulation, so your ability to maintain your body temperature. And this drives sweat to the surface of your skin and cools you, but can also result in dehydration. So, a loss of fluid can decrease your blood pressure and could lead to the kind of ischemia that I was talking about before.

Hannah - Thanks, David, and poor Ari is not alone in experiencing this phenomena. Jean Kennedy says that she just simply cannot do most forms of floor exercises. She apparently goes green with nausea if she does, whilst a second listener also had this to say on a matter.

Ross - Hi. I'm Ross from Birmingham. This is something that I've experienced it in the past and it can be quite uncomfortable. Having sought some medical advice, I found that eating properly, well in advance of exercise and being well hydrated before and during exercise that the problem went away.

Hannah - And David agrees with this advice.

David - Well, current research suggests that you can reduce the likelihood of nausea and vomiting by ensuring that you don't eat three hours before intense exercise. And also, keeping hydrated is key, so don't forget to drink plenty of water.



Try reading some of Mike Mentzer's work for he addressed your issue(s) clearly and to the point. Rather than myself extending my opinion, take it from the man who studied the subject intensively.

I hope this piece helps! Take some time away from working out and see how you feel after one week or so!

I do bodybuliding in the gym and in the last year or so i have been getting sick and dizzy atleast every 2 weeks while in a work out or after. I dont think. i should be getting this feeling since i train almost everyday and my diet is pretty well on point. Any one know why this would happen ? It only hapeens in summer time when its hot but i know guys in texas that train where its alot more hotter then were im at? Im just seeing what other people think. And ideas why this would happen to me?

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