Why do you get lightheaded when you stand

It’s common to feel light-headed when you stand too quickly from lying down or sitting, and after exercise. Fainting or dizzy spells can occur from a simple shift in body positioning that pulls your bloodflow downwards.

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“It’s called orthostatic hypotension or postural hypotension and it’s essentially a form of low blood pressure,” says exercise physiologist Michael Crawford. 

What happens when I feel dizzy?

In its acute (or short-lived) form, dizziness occurs from lying or sitting for long periods of time and then standing quickly, or when you’re dehydrated — like when you’re sick or when you exercise. There can be other underlying triggers for dizziness, but during exercise a quick change in the exercise position, difficulty or suddenly stop may result in low blood pressure causing dizziness.

With some forms of exercise you may be shifting the areas where your blood flows. Simply standing from a lying or seated position (more often during exercise) makes blood rush and gather down in your legs and abdomen. This means less blood is circulating and getting back to your heart, causing the decrease in your blood pressure. 

Cells called baroreceptors near your heart and neck detect this low blood pressure and send signals to your brain. Once your brain hears the news it tells your heart to pump faster to pump more blood in order to get your blood pressure back to normal. Until your blood pressure returns to normal, you may feel lightheaded.

Dehydration during exercise can also cause dizziness

Dehydration is known to decrease your blood volume and can also make you feel lightheaded as your brain sends messages to your heart to stabilize your blood pressure. Exercises that produce higher amounts of sweat are more likely to result in dehydration. 

When dizziness is a result of inactivity

Dizziness can also be a sign of postural orthostatic tachycardia syndrome (POTS). This condition most frequently affects young women who may struggle to stay active. People with POTS who exercise can feel dizzy or even pass out.

But there are ways to help offset these challenges. Crawford emphasizes it’s important to find ways to exercise because it increases blood volume, the size and strength of the heart and its pumping action.

“Most people I work with see some sort of improvement with exercise — they may still have symptoms but they occur less frequently,” he says.

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The important thing is to follow all of your treatment strategies if you have POTS. This includes taking your medication, increasing fluids, wearing compression stockings and gradually increasing physical activity over time.

Best and worst exercises to do for POTS

Newer research suggests that aerobic exercises that are not as gravitationally challenging are best for people with POTS. 

The ultimate goal is to progress over time to fully upright exercises so you can manage symptoms. Staying in a semi-recumbent position doesn’t do that.

“You can use semi-recumbent cycling, rowing machines and a seated stair-stepper to decrease the risk of syncope (passing out),” Crawford says. If weightlifting, work the lower body in seated positions with a leg press or seated abdominal exercises. Strengthening the lower body reduces blood pooling in the legs.

For the first three to four weeks try a semi-recumbent work at a moderate intensity level. You can gradually increase that intensity then progress to something more upright like a stationary cycle for another 3 or 4 weeks. 

“If that works well I transition people to a treadmill or elliptical machine. You’ll need to make sure you aren’t working too intensely. Once you’re feeling better, you can begin to work out normally,” he says. He suggests you stay away from free weights because a dizzy spell can increase chances you might drop the weight. Also, avoid high-intensity work or exercises with a rapid change in position.

How often to exercise with POTS 

Here is how people with POTS can build up their workout schedule:

• Start out working three days a week, resting between days.
• Add in a fourth day after about three weeks.
• After a few more weeks you can add a fifth day.

“Go for 20 minutes a day and add five minutes to that every two to three weeks. Eventually you can exercise 40 to 45 minutes most days in line with what’s recommended for everyone,” Mr. Crawford says. And remember these tips:

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• Hydrate, hydrate, hydrate — You need to prehydrate 30 minutes before you go to the gym with about 8 ounces of fluid. Drink water unless your doctor encourages you to have a sports drink. For every 15 minutes of exercise drink 4 ounces of fluid.
• Don’t skimp on warm ups and cool downs — People with POTS need to warm up and cool down very slowly for five minutes each. “For the warm up be sure to progressively increase your exercise over the first five minutes until you get to your conditioning phase. For cool down steadily decrease your exercise over five minutes before you stop,” Crawford says.
• Watch your target heart rate — Be sure you’re staying in your target heart rate where you feel comfortable. POTS patients don’t fall into typical exercise heart-rate levels so testing determines what they can tolerate. Know your parameters and stay within those levels.

“If you need help getting into exercise, start with getting an evaluation from a cardiologist or neurologist to make sure there aren’t underlying issues causing the condition,” Crawford says. “Once that’s sorted out, you should see an exercise physiologist who knows about POTS.”

Other medical conditions that cause dizziness

Not drinking enough fluids, fever, vomiting or severe diarrhea can also cause dehydration and dizziness.

And some medical conditions can prevent your body from responding rapidly enough to pump more blood when standing up such as:

• Extremely low heart rate (bradycardia).
• Heart valve problems.
• Heart attack or heart failure. 

There are also several nervous system disorders can disrupt your body’s normal blood pressure regulation system such as:

• Parkinson’s disease.
• Multiple system atrophy.
• Pure autonomic failure.

Endocrine problems that can cause dizziness:

• Low blood sugar (hypoglycemia).
• Diabetes (which can damage nerves that regulate blood pressure).
• Thyroid conditions.
• Adrenal insufficiency (Addison’s disease).

“In general, orthostatic hypotension can range from a few seconds to several minutes, but if it happens frequently it can be a flag for more serious medical conditions,” Crawford emphasizes. “See your doctor if you feel light-headed when standing up on a regular basis.”