Exercise Intolerance

What is exercise intolerance?

Exercise intolerance is the reduced ability to carry out physical activities. When you move, different parts of your body need to work together to make that happen. Problems with the various body systems involved in movement can lead to exercise intolerance. These include issues with your heart, lungs or muscles.

You may not be able to reach the maximum heart rate for someone your age because of your symptoms. During exertion, your body may only be able to take in and use 60% to 70% of the oxygen of someone without the condition. This can happen if your heart isn’t working well, like in people with heart failure.

Your heart pumps blood that carries oxygen to your body’s tissues and cells. If your heart can’t pump well, it has a hard time delivering oxygen throughout your body.

People with lung issues may find it hard to breathe in enough oxygen to meet their muscles’ need for oxygen. When you exert yourself, your muscles need more oxygen than they do at rest.

After you breathe in oxygen and your heart delivers it to your body (through blood), your cells need to use the oxygen. If your skeletal muscles aren’t working well, they can’t use that oxygen efficiently.

A problem with any of these steps (taking in, distributing or using oxygen) leads to exercise intolerance.

Exercise intolerance can keep you from doing activities you enjoy and lead to frequent hospital stays.

How common is exercise intolerance?

Exercise intolerance is common and has many causes. More than 6 million people in the U.S. have heart failure. About 50% of them have an intolerance to exercise.

What are the symptoms of exercise intolerance?

Exercise intolerance symptoms include:

• Shortness of breath.
• Fatigue.
• Leg discomfort or fatigue.
• Hyperventilation.

What causes exercise intolerance?

Exercise intolerance causes include:

• Heart failure.
• Congenital (present at birth) heart disease.
• Lung disease like COPD.
• Pulmonary embolism.
• Long COVID.
• Anemia.
• Concussion.
• Aging.
• Obesity.
• Diabetes.
• Kidney disease.
• Conditions that affect your skeletal muscles, like McArdle disease.
• Inflammatory disorders.

Some people may have multiple causes of intolerance to exercise. They may have heart failure, obesity and diabetes at the same time, for example.

How is exercise intolerance diagnosed?

A provider can diagnose exercise intolerance by using the following tests:

• Six-minute walk test. This involves walking at a normal pace to see how far you can go in six minutes.
• Exercise stress test. This walking or cycling test tracks your blood pressure, and heart rate and rhythm, as well as oxygen levels.
• Cardiopulmonary exercise testing (CPET). This consists of walking or biking while a provider monitors your heart rhythm, blood pressure, oxygen level and breathing. It’s the “gold standard” test and provides the most information. A mask you wear and breathe through monitors the depth and speed of your breaths and how much oxygen you’re taking in.

How do you fix exercise intolerance?

For many people, a program of physical activity (exercise training) is the best treatment for exercise intolerance. Exercise training means performing a physical activity at a moderate intensity for up to an hour three times a week.

A provider may make a custom exercise training plan for you. They may consider your condition and the cause of your intolerance to exercise. For example, if you have Long COVID, you may start with short sessions of low-intensity exercise like rowing or cycling. If you have COPD, you may do well with interval training, or short bursts of high-intensity movement.

Other treatments for exercise intolerance may include:

• Losing weight.
• Eating healthier foods or addressing a deficiency by adding more protein or vitamin D to what you eat.
• Using medicine or surgery to treat medical conditions that cause exercise intolerance.
• Receiving oxygen therapy.
• Taking part in pulmonary rehabilitation.

Can exercise intolerance be prevented?

Possibly. You can’t control some causes of intolerance to exercise, like a heart issue that’s present at birth. But you may be able to lower your risk of exercise intolerance by managing diseases that can cause it.

What can I expect if I have exercise intolerance?

Your experience with exercise intolerance will depend on what caused it. If you’re a teen who had a concussion, you’ll most likely be back to normal in a month or less. If heart failure causes your intolerance to exercise, you’ll be dealing with it for the rest of your life.

How do I take care of myself?

Because of the various causes of exercise intolerance, what’s best for you may be a bit different from what works for someone else. Follow your provider’s instructions for building your tolerance to exercise. That will likely mean getting a certain amount of physical activity at a set level of effort. It could mean eating more protein or making sure you manage the condition that caused your intolerance to exercise.

When should I see my healthcare provider?

You can expect to have regular checkups with your provider to see how well you’re doing. They’ll want to see what progress you’re making in the exercise training plan they made for you.

What questions should I ask my doctor?

Questions to consider asking your provider may include:

• What caused my intolerance to exercise?
• What are the specific actions I need to take to feel better?
• How often do you want to see me at a follow-up appointment?
• What goals should I reach for?