What Causes Nausea During a Workout?

A Marine recruit performs crunches during a physical training session.
A recruit with Golf Company, 2nd Recruit Training Battalion, executes a crunch during a physical training session at Marine Corps Recruit Depot San Diego, Oct. 21, 2019. (Lance Cpl. Grace J. Kindred/U.S. Marine Corps photo)

I often receive an email concerning that nauseated feeling you can get when exercising. There are a few issues that can cause this uncomfortable feeling, as well as many ways to prevent it. Here is the email to give you a better idea of the issues involved with this topic:

"I noticed that no matter how light or heavy my workout is for the day, I always experience some nausea. Even on the days I do very light cardio and just weight-lift ... could there be something causing this? I am training to pass the PFT using your training programs. I have the understanding that when you push your body to a certain point, vomiting will happen, but I experience this on the lightest of days. If you have any advice, please share!"

In my experience, that nauseated feeling has nothing to do with the level of your fitness. I have seen many people (including myself) who are above-average athletes toss their cookies during workouts. We used to joke in my younger days that "if you are not throwing up at the end of a PFT, you are not trying." Here are some things that can cause and prevent this unpleasant feeling:

1. Early morning workouts

Pre-breakfast workouts start your body exercising with minimal fuel in the tank. In other words, since you have not eaten in probably 10-12 hours, your blood-sugar levels are lower than normal. After any anaerobic activity like faster running, swimming, high-repetition calisthenics or weight lifting, you will feel completely drained.

Dizziness soon follows, and the next thing you know, you are nauseated. This also can occur in evening workouts if you skip lunch or afternoon pre-workout meals.

2. PFT anxiety

Many people when timed in events such as a physical fitness test can get very nauseated before exercise. There are ways to combat this feeling. Check out the "7 Tips on Dealing With PFT Anxiety" article.

3. Motion sickness

This is probably what caused your nausea. Many people who like to begin their workouts with crunches or other abdominal exercises can get motion sick while performing abdominal exercises. This occurs when your eyes are either closed while exercising or your eyes scan the ceiling freely. The answer to this is to simply do the old Navy trick I learned when first on a ship in the North Atlantic: look at the horizon to prevent motion sickness. So when doing ab exercises, lock your eyes on a fixed point on the ceiling of your workout area. You no longer will  feel sick, as long as you are fueled properly and not too anxious about your PFT.

A majority of the time, the causes for exercise-induced nausea are motion sickness or lower blood-sugar levels.

Stew Smith is a former Navy SEAL and fitness author certified as a Strength and Conditioning Specialist (CSCS) with the National Strength and Conditioning Association. Visit his Fitness eBook store if you’re looking to start a workout program to create a healthy lifestyle. Send your fitness questions to stew@stewsmith.com.

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