Light-Headed, Dizzy and Nauseous After Exercise? Here's What Could Be Happening

Skipping your cooldown can leave you feeling light-headed and/or nauseous after exercise.
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If you've ever stepped off the treadmill or elliptical and experienced light-headedness, dizziness or nausea, you know how concerning it feels and how it can dampen your desire to exercise in the future.

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There are a number of factors can play a role in feeling sick after a workout. Most commonly, feeling dizzy or light-headed is a result of not being able to get enough blood and oxygen to your brain.

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Feelings of nausea after a workout can be caused by not consuming enough calories to compensate for the amount of physical activity you're doing. And intense exercise or overexertion can cause nausea, shaking, weakness and dizziness.

Figuring out the source of the problem can help you avoid it in the future, leaving you feeling refreshed and happy you worked out. Here are some potential causes and what you can do to treat and prevent these symptoms.

Warning

Although getting dizzy and nauseous while exercising can be a normal symptom of dehydration, light-headedness may be a symptom of a heart or lung condition, per Harvard Health Publishing. Dizziness may also be a symptom of low blood pressure, which can result in shock and be life-threatening in extreme cases.

Chest pain, joint pain and shortness of breath when doing an activity you normally do easily are also symptoms that require medical consultation. If you experience these symptoms, contact your doctor to rule out or treat any underlying conditions and adjust your exercise routine to address your symptoms.

6 Causes of Post-Workout Light-Headedness, Dizziness and Nausea

1. Skipping the Cooldown

Working out — particularly doing cardio — is designed to make your heart work harder than when at rest. To do that, you need to start a session gradually to slowly raise your heart rate. And you need to end your workout gradually, too, so your heart eases back to its normal pace.

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That gradual end is your cooldown. It gives your body the time it needs to return to normal, including the way it pumps blood through your system. If not, your blood can pool in your legs, causing dizziness and possibly fainting, according to the American Council on Exercise (ACE).

Fix It

"Do five minutes of easy walking — 10 minutes if you're just getting into an exercise plan — to bring your heart rate down," says Richard Peng, CDE, CPT, a clinical exercise physiologist and diabetes educator with HealthCare Partners Medical Group in Los Angeles. Follow this with some static stretches.

If you feel rushed and need to cut an exercise session short, take the time from the high-intensity part of your workout, not from the cooldown.

2. Dehydration or Hyponatremia

Dehydration can sneak up on you. And once you start exercising, the harder you work and the more water you'll lose through sweat, which contains not just water, but also essential electrolytes like sodium.

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Losing too much water and not replacing it leads to dehydration, while an abnormally low level of sodium in your body can cause a condition called hyponatremia, which includes symptoms like nausea and vomiting, fatigue and headache.

But don't go overboard with water, either. "In extreme cases of prolonged exercise, too much could result in diluting the normal balance of sodium in your body (hyponatremia)," Peng says.

Fix It

"Drink water periodically as you exercise," Peng says. "In most cases, you don't need to drink a fluid with carbohydrates and electrolytes unless exercising for over an hour."

If you're going to work out for longer — taking an afternoon hike or playing softball with friends — carb- and electrolyte-enhanced fluids can be part of your hydration plan.

Consider these guidelines from ACE:

  • Two hours before exercise: Drink 17 to 20 ounces of water.
  • During exercise: Drink 7 to 10 ounces of fluid every 10 to 20 minutes.
  • After exercise: If you sweat so much that you lose weight, drink 16 to 24 ounces of fluid for every pound lost.

3. Overexertion

Pushing your body too hard can result in your heart working too hard and not getting enough blood to your head, resulting in light-headedness or dizziness. Intense exercise also pulls blood away from the lining of your stomach and intestines, which can cause nausea, says Lon Kilgore, PhD, of CrossFit Santa Cruz in California.

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Some athletes view these symptoms — nausea, shaking, dizziness or even vomiting — as a badge of honor, according to Kilgore. However, there's no honor in hurting yourself by exercising too much.

Dr. Kilgore reports that intense exercise interferes with your digestive system's functioning, and if you throw up, you expose the lining of your esophagus to harsh stomach acid, potentially damaging it.

Fix It

If you're new to exercise, start slow and gradually work up to higher-intensity workouts.

Staying within your target heart rate zone is an excellent way to pace yourself when you're exercising. You can figure out your target heart rate zone by subtracting your age from the number 220, then multiplying that number by 0.5 and 0.85. Stay in the middle of your target heart rate zone.

You can also use the "talk test." According to researchers at the University of New Mexico, "When an exerciser reaches an intensity at which he or she can 'just barely respond in conversation,' the intensity is considered to be safe and appropriate for cardiorespiratory endurance improvement."

4. Low Blood Sugar (Hypoglycemia)

"When you exercise, your body draws the energy it needs from glycogen, the readily available form of sugar stored in your liver and your muscles," Peng says. "Not having enough readily available glycogen for your workout could cause your blood sugar to drop."

Having low blood sugar (called hypoglycemia) can cause dizziness as well as irritability and inability to focus. The risk is even greater in people who have diabetes, as the combination of exercise and certain diabetes medications, including insulin, can increase the likelihood of a blood sugar drop.

Fix It

"Have a meal with protein and carbs two hours before exercise," Peng says. "This way, blood sugar will be at its peak when you work out."

If you have diabetes, work with your doctor to find the best eating and exercise timing for you and to decide whether you should test your blood sugar before or after exercise — or maybe even during a brief break in your activity regimen.

5. Posture Orthostatic Tachycardia Syndrome

Sometimes the cause of post-workout dizziness involves the heart. One little-known condition is postural orthostatic tachycardia syndrome (POTS).

It often affects young people born female and causes the heart to race from even minimal exercise — especially if your activity includes changes in position, from reclining to standing up quickly, per the Cleveland Clinic. This can lead to dizziness and even fainting.

Fix It

If you feel yourself getting dizzy or light-headed while you're working out, stop immediately and seek medical attention. Your doctor can help you come up with a routine that works for your weight, medical history and conditions.

6. Benign Paroxysmal Positional Vertigo

Dizziness can also be caused by a condition called benign paroxysmal positional vertigo (BPPV). This vestibular disorder typically comes on suddenly and is caused by movement of crystals in your inner ear.

Fix It

BPPV can be treated by specially trained physical therapists. And if you consistently have issues with BPPV, talk to your doctor about exercises that can help improve your balance and exercise with a friend who can help you in the event of a dizzy spell.

Treatment: What to Do About It

If you experience light-headedness, dizziness and nausea directly after working out, there are certain things you can do to immediately help your symptoms subside.

If you feel dizzy, light-headed or nauseous while exercising, stop immediately. Continuing to exercise while feeling faint could lead to tripping, falling and injuries. Take a break. You may find it helpful to sit down with your head between your knees as you restore blood flow to the head.

Or find an open area where you can lie down on the floor and put your feet up. This will help increase the blood flow to your upper body and head. Sip on a sports drink that contains electrolytes, but don't drink too much too fast.

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