If you're overheated, dehydrated or full of food, you may feel like you're going to throw up during a workout. Exercise-induced nausea is usually preventable by changing your environment or eating and drinking habits. If the condition persists after making these changes, consult your doctor to rule out any underlying conditions.
Eating
Nausea can be triggered when you eat too soon before exercising. This effect was demonstrated by a Nagoya University study in which participants who waited to exercise until 60 minutes after eating were less nauseous than those who worked out immediately after eating. Not eating at all before exercise was also shown to trigger nausea. Try eating a small meal of easy-to-digest foods about an hour before your workout.
Water
If you always experience nausea during exercise, you may not be drinking enough water during your workouts. Dehydration can cause nausea, and vomiting can cause additional dehydration, perpetuating the cycle. Keep a bottle of water with you during your workout and take frequent sips to prevent dehydration. If you end up having to vomit, stop your workout and drink more water to replace lost fluids.
Heat Exhaustion
Exercising outdoors on a hot day or in an overheated indoor environment can cause heatstroke or heat exhaustion if you're working too hard. In addition to nausea, symptoms include heavy sweating, weakness, confusion, dizziness, headache, a too-fast heartbeat and dark-colored urine. If you experience these symptoms and are in a hot environment, get to a cooler place, drink water and rest until you feel better. See a doctor if your symptoms don't improve within 30 minutes.
Treatment
When you experience nausea, no matter what the cause, you should stop exercising and sit down -- avoid lying down. Drink water, a sports drink, fruit juice or flat soda to calm your stomach. If your doctor rules out other causes, try changing your eating habits. Eat several small meals per day instead of a few big ones, and eat primarily easy-to-digest foods like potatoes, noodles, rice, soups and gelatin. Avoid greasy and spicy foods, as well as alcohol and carbonated drinks, before working out.
