Feel Sick After Exercise? A Scientist Explains Why, And How to Prevent It

We exercise to feel better. While some of us get highs after a workout, some of us leave the gym feeling sick. It can still be uncomfortable even though it is only temporary.

There are a few good explanations for why this may be happening, so if this happens to you, there is probably no reason to be alarmed.

Blood flow to the working muscles, brain, lungs, and heart increases when we exercise.

The increase in blood flow is caused by the sympathetic part of the autonomic nervous system, which helps regulate all of our bodily functions. It widens the arteries so they can carry more blood.

The sympathetic nervous system, which normally drives our fight or flight mechanism, simultaneously narrows the blood vessels going into our gastrointestinal system during a strenuous workout by up to 80 percent.

There is a limited amount of blood in the body, and the increased oxygen demand by some tissues can only be met by altering the amount of blood going to other tissues.

It is possible that blood supply will be reduced in areas that don't need as much oxygen at that time. Whether or not you have recently eaten can be the case.

Let's say you just ate a meal and are about to head to the gym or run. The food stretches our stomach, causing the release of acid and enzymes needed to digest it.

Increased demand for oxygen and blood flow to the stomach and other gastrointestinal tissues can be caused by the stomach muscles becoming more active. Blood flow to the gastrointestinal structures increases when there is a change in the autonomic nervous system.

It is possible that the conflict in the body from different tissues may be the reason for nausea after a workout. As demand changes, the body has to adjust its blood flow to the tissues.

When we work out, blood needs to go to the muscles, heart, lungs and brain, meaning blood flow is reduced in less active tissues. When blood flow is reduced in this area, it causes feelings of nausea.

The stomach and other abdominal organs can be compressed during exercise, which may contribute to feelings of nausea. As the heart rate and oxygen demand in tissues increases, so the body draws larger volumes of air into the lungs is an issue in squatting.

This causes the abdominal organs to push down harder. The abdominal wall is one of the muscles that help further squeeze the abdominal organs. It can result in nausea and vomiting even on an empty stomach.

The stomach lining can be damaged due to the decrease in blood flow and oxygen available to the organ, according to some evidence. This would cause nausea.

In extreme circumstances this can cause bleeding of the stomach lining in endurance and long distance athletes.

When to eat

You are more likely to experience nausea if you exercise immediately or up to an hour after eating.

It takes approximately two hours for food to be broken down by the stomach and enter the small intestines, so if you experience nausea after workouts, it might be best to wait at least two hours after a meal.

If you eat before a workout, you may experience nausea. High fiber, fat, and even high protein foods are linked to a greater chance of nausea after a workout.

The digestibility of supplemental protein, particularly the shakes, is slower. The stomach tries to digest it during a workout.

Certain fats, particularly saturated ones, may cause nausea differently, with animal models showing they irritate and damage the lining of the gastrointestinal tract, which can cause vomiting in the brain.

Consuming sports drinks and other high-carbohydrate drinks is linked to nausea during and after a workout. These drinks stay in the stomach for a longer time than other drinks.

There are a couple of things you can do if you experience nausea after a workout. First, change or reduce your workout, and build up intensity slowly. The longer the workout, the more blood is drawn away from the stomach.

It's a good idea to drink enough water before and after a workout, as both too little and too much can cause nausea.

Choose the right food, such as bananas or sweet potatoes, and avoid it two hours before. If you plan to work out, these will be easier to digest than other foods.

Adam Taylor is a professor at Lancaster University.

This article is free to use under a Creative Commons license. The original article is worth a read.