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Why am I getting nauseous when I'm weightlifting?

Dear Alice,

It's been about three months since I worked out regularly. I find that lifting for strength (i.e. 80% of max for 5-8 reps) causes me to feel nauseated about 3/4 through the workout sometimes, so that I can't bring myself to finish. I took a weight training course last semester and was affected the same way every once in a while. I warm up, stretch before and after, breath when I lift, drink plenty of water, take care not to eat 1 hour before working out, skip a day between workouts, don't lift more than I can handle (I reduced the weight from what I ended on in the class to a seemingly suitable weight. I got a 98 in the class incidentally). What's going on?

Virtually,
Pre Van Damm

Dear Pre Van Damm, 

Sounds like something isn’t working out! It could be because the digestive system slows down as the body revs up, which might make you feel like your stomach is doing somersaults. Based on what you’ve written, it’s hard to tell whether the nausea you’re feeling is due to physical exertion or something else like low sodium levels or pre-workout supplements (more on these in a bit). However, understanding potential causes can help you decide whether your symptoms warrant a trip to a health care provider. 

Physical exertion can sometimes lead to an upset stomach. Exercise activates the sympathetic nervous system (the part of your nervous system that’s responsible for the “fight or flight” response). When this happens, the body reduces blood flow to organs in the digestive system to divert as much blood as possible to the heart, lungs, and skeletal muscles. As a result, digestion slows down. This can cause some people to experience gastrointestinal discomfort or nausea. 

That said, there may be several other reasons for your queasy quandary. Some of these reasons may include: 

  • Low blood sodium levels. Also known as hyponatremia, this usually occurs when there’s too much water in the body and too little sodium. Symptoms include nausea and vomiting, muscle cramps or weakness, and headache. Hyponatremia can happen if you drink too much water after sweating from an intense workout on a hot day. Since sweat is made up of salt and water, drinking plain water alone won’t replace the electrolytes that you lose through sweat. In fact, drinking too much water may end up diluting the remaining sodium in your body. Certain medications used to treat depression and epilepsy can also contribute to low blood sodium levels. 
  • Caffeine. Caffeine isn’t just in your morning cup of joe. It’s a common ingredient in pre-workout supplements and energy drinks because it can enhance physical performance across a wide range of sports and exercises. For instance, caffeine can improve muscle endurance, strength, and power during weightlifting. However, ingesting caffeine may cause side effects such as nausea, headache, insomnia, and muscle tremors. 
  • Sodium bicarbonate. Another common additive in pre-workout supplements, sodium bicarbonate can improve performance in muscular endurance activities and high-intensity sports. However, it may be associated with gastrointestinal discomfort such as bloating, nausea, and abdominal pain. 

As you move forward, it may also be helpful to consider your weightlifting goals. Are you lifting to maintain your fitness? If so, choosing a weight that allows you to complete three sets of eight to twelve repetitions without struggling to finish each set, and working out two to three days a week is more than sufficient. If you’re seeking to improve muscle strength, choosing a higher weight that challenges you during each repetition, and completing two to five sets of three to five repetitions is recommended. It’s also a good idea to incorporate rest days between workouts so your body can repair damaged muscle tissue. Looking to increase muscle size and build a physique like a body builder? Doing one to three sets of eight to twelve repetitions with a moderately challenging weight may be a good place to start. It’s useful to keep in mind that a moderately difficult weight allows you to complete ten repetitions without straining, and without holding your breath or shaking excessively. 

In addition to your workout routine itself, some eating and behavior-based strategies you might explore to reduce nausea and discomfort during your workout include: 

  • Eating a meal around four hours before a workout. 
  • Eating a simple carbohydrate snack or carbohydrate and protein snack an hour before a workout (if necessary). 
  • Avoiding foods high in fat, fiber, or protein which are harder to digest. 
  • Drinking electrolytes to replenish the sweat that you’ve lost. 
  • Reducing the dosage of pre-workout supplements with caffeine or sodium bicarbonate. 
  • Increasing the time interval between ingesting supplements and working out. 

Making small changes to your pre-workout routine and experimenting with the amount of weight you’re lifting, or the number of repetitions, may help get you back on track. If you don’t experience relief from these modifications to your workout and eating plan, it may be best to speak with a health care provider. An exercise physiologist or sports medicine specialist may also be able to offer more insight and useful strategies to help you manage your condition. 

Hope this helps to settle your stomach and lift your spirits!  

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Last updated Mar 08, 2024
Originally published Mar 15, 1996