Human Anatomy at Colby

Calvin Robbins: The Science Behind Run Til You Puke

February 23, 2015 · No Comments

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Have you ever heard of somebody exercising to the point of vomiting? Or have you done it yourself? I never have, but during the digestive system lecture of the BI 265 Human Anatomy and Physiology class this Jan plan I had a sudden realization as to why this happens.

While nausea may be a common feeling when working out due to food or liquids in the stomach being bounced around, that is not usually why we actually end up vomiting during hard exercise. In fact, one of the biggest causes starts with the respiratory system. The job of the respiratory system is to remove CO2 from the blood and replace it with O2. During exercise, cells produce CO2 as sugars are broken apart to make ATP, which the cell uses for energy. Some of the CO2 byproduct goes into the blood and attaches to hemoglobin, but the vast majority of CO2 is actually transported as carbonic acid, which induces respiratory acidosis. When a person is doing anaerobic activity, such as running at full speed for a long enough time, their lungs are unable to get all of this accumulating CO2 and carbonic acid out of the bloodstream thus creating increasingly acidic blood. It is not due solely to lactic acid as many people believe, but the inability to exchange enough gas in the lungs.

As the blood gets increasingly acidic, the body has to find a way to get rid of all of this acid. One of the main ways the body has of releasing acid, as you may have already guessed, is through vomiting. As you vomit, the hydrochloric acid used for digestion is expelled from the stomach, which is lined with highly vascularized rugae. As the acid is forced out of the stomach, the acidic contents of the blood are pulled out to replace the Hydrochloric acid that was lost from vomit. Following the same thought process, this is why excessive puking will produce alkalosis (high pH) in the blood.

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If you vomit frequently after heavy exercise you should take a few steps to achieve a healthier and more beneficial workout:

  1. Base your workouts on a heart rate range.  This will force you to stay within a set range for aerobic exercise, which can be roughly calculated based on your age. Usually 85% of max heart rate is the highest you should be going for an aerobic workout to prevent acidosis.
  2. Drink plenty of water; if you are vomiting due to dehydration, it is a much more severe issue than acidosis. Steadily drinking water before, during, and after exercise will help, as well as a small amount of sports drink to replace some of the ions lost during the work out.

It takes a lot of anaerobic exercise for the body to get to the point of vomiting. This kind of activity, contrary to what some may think, is very bad for your body, and is not something to strive for in a hard workout. Remember to drink plenty of water and keep a reasonable heart rate target in mind for a healthy and effective workout.

Categories: Human Health · Lab · Special Activities
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