If you’ve ever finished a particularly hard running workout or given it your all in a race, your immediate surge of glory and pride might be partially clouded by the sudden urge to vomit.
Nausea after running is an unfortunately common, and certainly undesirable, side effect of hard exercise and can put a damper on enjoying the afterglow of a good workout.
Throwing up after running, or feeling like you want to throw up after working out, can occur for a variety of reasons.
Although nausea after running or exercise is certainly unpleasant, it’s usually not a major cause for concern. With that said, having a few tools in your “tool kit“ or how to stop feeling nauseous after running can certainly make for a more pleasant post-run experience and make you feel more motivated to get out there and get your miles in.
This article will discuss the 5 main causes of nausea after running or working out and how to stop feeling nauseous after running.
Why Am I Nauseous After Running and What Can I Do About It?
So, what causes throwing up after running? Why are you nauseous after working out?
If you experience nausea after running, you are not alone. Studies suggest that up to 83% of marathon runners complain about various GI symptoms that are associated with their running.
There are several potential reasons why you might feel nauseous or sick to your stomach after running. Here are some of the top causes of nausea after exercise:
#1: Running Too Soon After Eating
Typically, the most common reason for throwing up after running or feeling like your body is trying to vomit is due to the fact that when you exercise, particularly at a high intensity, your digestive system essentially shuts down.
In order to properly fuel your working muscles with oxygen rich-blood and nutrients, the body has to divert blood away from the stomach and digestive tract so that there is enough to circulate to the muscles, lungs, and heart.
Essentially, your body maximizes the efficiency during exercise by trying to meet the elevated oxygen demand of your heart and muscles by making compensatory reductions in the circulation to nonessential regions of the body, such as the large digestive tract.
Although the stomach and gut will still receive minimal blood flow during exercise to support survival, as much blood as possible is shunted away from this area so that it can instead be diverted to where it is needed most—the working muscles, heart, and lungs.
However, because the blood flow to the digestive organ is so minimal, your stomach and intestines do not have the resources they need to carry out normal digestive functions.
For this reason, digestion essentially ceases during exercise, and any remaining food in your stomach or intestines will sit around in a holding pattern until your physical activity has stopped and circulation to the gut has resumed.
As the food sits there, it can begin to ferment and create gas, and even just the sensation or weight of the food in your stomach, coupled with the mechanical jostling and shaking that occurs as you run, can leave you feeling like you are going to throw up.
Additionally, the harder you push yourself, or the higher the intensity of the workout, the higher the oxygen demand from the muscles and heart. This means that even more blood must be shunted away from the digestive system.
If you are running a marathon or a long run where you have to take in fuel, such as sports drinks, energy gels, or other sources you introduce into your stomach, if you are simultaneously pushing your body at such a high intensity that hardly any digestion can take place, the food and drinks will sit around in your stomach without getting digested.
Then, when you stop running, you might be overcome with nausea and will, unfortunately, see the return of all of your race fueling at your feet when you throw up after running.
#2: Consuming Energy Gels
Another often overlooked cause of nausea during running is the ingestion of energy gels without sufficient water intake.
Energy gels, sports drinks, energy chews, and other race-fueling options that are high in simple sugars can be difficult to digest, even when you aren’t running. The body needs water to help break down and absorb these sticky products.
If you are finding that you are getting nauseous on your long runs or during marathons or other long races, your fueling strategy could be to blame, and it might be that you are consuming too many simple sugars too quickly, particularly in the absence of water.
You might find that you do better with sports drinks in which the hydrating fluids are built into the fueling option.
Or, many runners find that they do better with race fueling options that don’t contain as many simple sugars but have a slower release format that the stomach seems to tolerate better during exercise. Examples include Ucan and Maurten.
#3: Hydration Issues
Interestingly, both dehydration as well as drinking too much water or sports drink while running can cause nausea after your workout.
Finding the optimal fluid balance and rate of fluid ingestion during running usually takes some experimentation.
Although it is typically recommended to drink about 4-6 ounces of water every 15 to 20 minutes, depending on your body size, workout intensity, duration, sweat rate, and the climate or temperature, your own fluid tolerance during running may vary.
Additionally, most runners do best by sipping water or sports drinks during their runs rather than trying to have all 4 ounces in one bolus every 15 minutes.
The slow and steady stream of fluid intake will help give your stomach ample time to absorb the liquids rather than suddenly overloading it with a bunch of water or sports drink all at once.
However, dehydration can also cause nausea after running, so it’s important to ensure that you drink enough fluid during your workouts.
#4: Intra-Abdominal Pressure
When you exercise, particularly when you are running at a high intensity, there is an increase in intra-abdominal pressure, which means that there is more pressure on the contents of the abdominal cavity, including the stomach.
When you run, you are engaging your core muscles and breathing more heavily.
As you do so, the diaphragm presses down further into the abdominal space and the core muscles, such as the rectus abdominis, internal and external obliques, and especially the transversus abdominis, a deep core muscle that in circles your entire torso like a corset, contract more forcefully and repetitively, decreasing the viable space in the abdominal cavity.
Basically, high-intensity running creates a squeeze on the organs in the abdomen. When the stomach is squeezed, it can force the contents back up into your esophagus and potentially all the way out so that you throw up after running.
Additionally, if you have gastroesophageal reflux disease (GERD), a hiatal hernia, or issues with the sphincter between your stomach and esophagus, it’s even more likely that you will vomit after running because all of these conditions increase the ability for the contents of the stomach to travel back up the esophagus to the eventual end result of throwing up.
To help prevent throwing up after running, if you are a runner suffering from GERD, it is best to avoid trigger foods that can exacerbate the condition, such as tomato products, citrus fruits, other acidic foods such as vinegar, fatty foods, alcohol, and coffee, particularly before running, though at all times in your diet, if possible.
#5: Eating the Wrong Foods Before Running
Although the advice to stay away from acidic foods, such as citrus, coffee, processed cheeses, orange juice, and soda, is particularly pertinent for runners with acid reflux or GERD, it’s also a good practice for anyone to avoid these foods before running.
Acidic foods can increase the likelihood of feeling nauseous or throwing up after running because they irritate the stomach.
The entire environment of the stomach is more acidic, which ultimately slows gastric emptying, or the rate at which the contents of the stomach are passed onto the small intestine.
It also increases the experience of a “sour stomach,” which essentially describes an overly acidic stomach that can increase the risk of vomiting whether or not you are exercising.
Throwing running into the mix exacerbates the risk of vomiting even further.
Ultimately, to prevent nausea after running, try to be mindful of what you are eating before you run and how long you are waiting to run after you eat. Try to keep your body cool and hydrate gradually but sufficiently. You may also need to reduce the intensity of your workout.
Have you been experiencing other ailments during or after running in addition to nausea? If so, we may be able to help. Check out some of our other guides for potential causes and helpful advice:
Headache After Running? 4 Main Causes of Headaches After Running