Dizzy After Exercise? Here’s What Could Be Going Wrong

Exercise is supposed to give you a boost of feel-good endorphins, not leave you feeling faint, dizzy or light-headed after your workout. Sometimes, though, that's just how you feel. However, once you know the reasons this can happen, you can take some pre- and post-exercise steps to avoid it.

Dizziness After Exercising
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Dizzy After Exercise: You Skipped the Cooldown

Cardio is designed to make your heart work more efficiently over time. To do that, you need to start a session gradually to slowly raise your heart rate and end your workout gradually, too, so your heart eases back to its normal pace. 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, and that can cause dizziness and possibly fainting, according to the American Council on Exercise (ACE).

The answer: "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 simple stretching (important for muscle health).

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.

Read more: Post-Workout Lightheadedness

Dizzy After Exercise: You Could Be Dehydrated

Dehydration can sneak up on you. You might be short a few glasses of water before you ever get to the gym. Once you start exercising, the harder you work, the more water you'll lose through sweat. And if you're outdoors and the temperature is high…more water loss. Not sure you're dehydrated? "Dark yellow urine is another sign," Peng says.

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

If you are going to work out for longer periods of time — like 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.

Important: Don't go overboard with water, drinking quarts at a time rather than cups. "In extreme cases of prolonged exercise, too much could result in diluting the normal balance of sodium in your body, a dangerous condition called hyponatremia," warns Peng.

Read more: Feeling Dizzy or Lightheaded After Running

Dizzy After Exercise: You Could Have Low Blood Sugar

"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 explains. "If close to mealtime, 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. "In severe situations, you might not be able to react to my voice even if you can still hear me," Peng says. The risk is even greater in people who have diabetes because the combination of exercise and certain diabetes medications, including insulin, can up the likelihood of a blood sugar drop.

The answer: "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 health care team 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.

When the Problem Is More Serious

It's true that low blood sugar, dehydration or a missed cooldown can make you dizzy after a workout. Sometimes, though, the cause involves the heart. One little-known condition is called POTS (for postural orthostatic tachycardia syndrome). It often affects young women and causes the heart to race from even minimal exercise — especially if your activity includes changes in position, from reclining to standing up quickly, the Cleveland Clinic explains. This can lead to dizziness and even fainting, the Cleveland Clinic adds.

Anytime you feel dizzy during exercise, stop. Often, drinking water and having a light snack will help. But if it's ever accompanied by chest pain, significant shortness of breath or a fast or irregular heartbeat, get immediate medical attention, urges the American Heart Association.

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