Experiencing symptoms of nausea and vomiting while running isn’t uncommon. Nausea is most commonly caused by stress that is put on a runner. Physically, the nausea-like symptoms are the result of the release of adrenaline. Adrenaline disrupts the stomach because it pulls blood away from the intestine and sends it to the heart, brain and skeletal muscle. Without proper blood flow, the body can’t move food through the digestive system. Moreover, a rush of adrenaline can also cause muscle tension in the abdomen, leading to tension that squeeze the stomach and result in nausea and vomiting. Because adrenaline disrupts the digestive process, runners who struggle with nausea and vomiting should take extra care with their pre-race meal.

Switch to a low-fiber meal 30 minutes to 2 hours before your run, such as a small bowl of oatmeal with a small banana. This will provide a small boost to your blood sugar levels, but will not spike your insulin. You don’t need to load up on carbohydrates or calories before most of your normal training sessions, but might want a little extra fuel for harder workouts or long runs. You'll have to experiment. To find your optimal timing window, try eating a medium sized snack 90 minutes before your next run. If your stomach handles it well, try moving the same snack forward 15-20 minutes. Likewise, if you experience stomach issues and cramping, push back the timing of your snack 15-20 minutes.

Runners who suffer from nausea and cramping should consider a liquid pre-race breakfast, which is digested quickly and doesn’t sit in the stomach, as opposed to more solid foods like a bagel and a banana.

Avoid the use of anti-inflammatory drugs like Advil and Ibuprofen. Recent research points to a strong correlation to NSAID use and nausea during long distance events.

The most common cause of vomiting and nausea during hard workouts and races is also due to the shutting down of the digestive system as exercise intensity increases. As the need for oxygen-rich blood in the running muscles increases, the body begins to shunt blood away from non-critical resources, such as digestion, to help feed the muscles. In addition, overheating and running in hot conditions decreases blood flow to the digestive system. The most effective way to avoid nausea-related systems during your workout is to pay close attention to what and when you eat before and during your run. If you plan on consuming fluids or fuels during a run, make sure you have a carefully orchestrated strategy that you’ve practiced in training. When taking gels or other simple sugars during a long run, make sure to take them with water and not with a sport drink. In the absence of water, the digestive system will have to work harder to break down the gel into usable energy. Likewise, don’t consume gels too quickly. Simple sugars are absorbed into your blood stream as glucose. The sugar will stay in the blood stream until absorbed by the working muscles or other organs. Too much sugar in the blood stream will make you sick, the same as it would if you ate too much candy.

In addition, dehydration can lead to overheating and can also slow stomach emptying. However, excessive intake of sodium, potassium, or other electrolytes can lead to bloating, nausea, and vomiting. Therefore, you need to develop a detailed hydration strategy that you implement and experiment with in training while running hard.