Why You Get Dizzy or Light-Headed When You Work Out

The last thing you want is to feel dizzy and light-headed when you come up from that last burpee or finish your final rep when weight lifting. But what's going on when you're facing these symptoms, and are they cause for concern?

Here, four common reasons you might be experiencing these unpleasant (and somewhat alarming!) side effects during or after exercise — and how to prevent them, according to Jeffrey A. Morrison, M.D., founder of the Morrison Center in New York City.

You're Dehydrated

Getting the spins during your workout? Dehydration could be a culprit. If you find you're not taking a single sip for your entire routine — or you weren't drinking up in the hours before exercising — that could be your problem. The simple way to ensure you're staying well hydrated is pretty obvious: drink enough water, and drink it often.

You Have Low Blood Sugar

One of the primary reasons you may feel dizzy both during and after exercise is because of low blood sugar, says Dr. Morrison. Your blood sugar levels dip and spike throughout the day based on the foods you eat, as well as how quickly and how well your body breaks them down.

To avoid the dizzying effects of low blood sugar (fatigue and headaches are among the various other symptoms), eat something that's light enough for your stomach to handle and digest before exercise, but substantial enough to keep your blood sugar stable, suggests Dr. Morrison. Try half a serving of brown rice protein powder or pea protein powder mixed with 4 ounces of almond milk for a quick pick-me-up before a workout, he recommends. You may also consider reaching for a bottle of coconut water. It'll keep you hydrated, and the natural sugars will make sure your blood sugar doesn't tank.

You Have Low Blood Pressure

If you experience sudden dizziness during a particularly intense, weight-bearing workout such as running or cycling, low blood pressure could be to blame. Generally, "people who are lean, have a faster metabolism, and get light-headed from just standing" are more susceptible to low blood pressure, says Dr. Morrison. If this sounds like you, try adding a pinch of sea salt to veggies to up your levels, he recommends. If the symptoms persist, you may want to consider talking to your doctor about postural orthostatic tachycardia syndrome, a little-known disorder that can cause frequent dizziness and heart palpitations.

What, exactly, is considered low blood pressure, and what's considered typical? You're looking for a healthy blood pressure reading as close to 120/80 as possible, according to the National Institutes of Health. Some define the low blood pressure benchmark as roughly 90/60, but what is considered "low" for someone else may not be "low" for you, so you should consult your doctor if you're concerned about your numbers.

You're Forgetting to Breathe

Your trainer or instructor is on to something when they tell you to belly breathe. "Everyone takes breathing for granted because it's an automatic process," says Dr. Morrison. "If your [breathing] isn't synchronized with what you're doing, you might not be letting enough oxygen in and carbon dioxide out," which can cause sudden dizziness, he adds. You may be holding your breath during isometric moves (such as planks and squat holds) or breathing heavily through your mouth during drills and sprints. Try to focus on your breath when working out to avoid dizziness.