Exercise intolerance might sound like that feeling you get when you don’t want to go to the gym or push yourself through a tough workout, but it’s actually a bigger issue than that.

Sure, everyone gets tired when pushing themselves through another set of dips. But exercise intolerance is when you feel too fatigued to perform a certain workout at your maximum effort level and for an extended duration. This inability to perform isn’t simply because you’re tired, but due to a larger problem, like chronic diastolic heart failure.

While exercise intolerance is a common symptom among those who suffer from heart disease, mitochondrial disease, or certain metabolic disorders, exercise intolerance is the primary symptom of chronic diastolic heart failure.

Symptoms of exercise intolerance include experiences of unusual and severe post-workout pain, fatigue, nausea, vomiting, and other negative effects. These symptoms aren’t directly caused by the workout itself, but instead are due to a specific heart disease.

What Does It Mean to Have Diastolic Heart Failure?

Diastolic heart failure occurs when the heart is unable to adequately fill with blood during the relaxed phase of the heartbeat. This leads to less blood being pumped out to the body, reducing the amount of oxygen and nutrients that your body has available during exercise. Ultimately, this will reduce your ability to perform physical activity and aerobic exercise, as well as everyday activities.

The reduction in aerobic capacity is largely caused by insufficient blood flow to active skeletal muscle, paired with impaired cardio output.

To truly avoid a rough bout of exercise intolerance, you must learn the signs and symptoms. So, what are they?

The Signs and Symptoms of Exercise Intolerance

There are several ways to tell if you might be experiencing exercise intolerance. It’s important to stay tuned in to how your body is feeling and functioning. Contact your doctor if you have concerns about the symptoms you’re experiencing.

Muscle Cramps

Muscle cramps can happen to anyone, even professional athletes. The difference is that they occur in individuals experiencing exercise intolerance with a minimal amount of exertion. And then, they may last for days at a time.

Cramps can also have a late onset, striking even after an individual has fallen asleep.

Rapid Loss of Breath

Individuals who experience exercise intolerance will reach their limit during exercise, and even everyday activities, faster than those without heart failure.

The reason for this is due to the reduced blood flow that occurs with heart failure. If you’re unable to pump out an adequate amount of blood, you will tire more quickly.

Muscle Fatigue or Tenderness

Feeling extreme heaviness or tenderness in the muscles is another sign of exercise intolerance. If your muscles feel unusually heavy after easy or moderate exercise, be sure to notify your doctor.

Insufficient Heart Rate

Another factor exercise intolerant individuals should look out for is an insufficient increase in heart rate, despite increased physical activity. If you are noticing that your heart rate does not increase with an increase in activity, talk to your doctor.

Try using a heart rate monitor to determine if your heart rate is healthy.

Avoiding Exercise Intolerance

Now that you are aware of some of the symptoms of exercise intolerance, it’s important to know what to do to avoid any harm to your well-being. Here’s what you need to know to keep exercise intolerance at bay.

Don’t Stop Exercising

While you might think that exercise intolerant individuals should stop working out, that’s not necessarily the case. A study in the journal Circulation suggests that the benefits of exercise training in patients with heart failure can actually improve exercise intolerance. Training usually not only increases how long you work out, but how hard you work out. While exercise training programs for those who are exercise intolerant vary, one study found that circuit weight training for eight weeks could spark a modest, but significant, increase in aerobic ability (called peak VO2).

When You Exercise, Take Frequent Rest Periods

While you may not be able to work out for long periods of time with no break, you may be able to work out longer if you build in regular rest periods.

Low-intensity exercise regimes that call for regular and frequent rest periods are often better tolerated by those with heart failure. You won’t overwhelm your body, and you’re more likely to feel an onset of exhaustion if it hits you.

Listen to Your Body

Don’t try to test your limits. This isn’t the Super Bowl or the World Cup, and keeping your body happy and healthy is priority.

Educate yourself on how to listen to your body. Pace yourself during physical activity so you’ll be able to notice when your body needs a break. Ideally, you want to stop exercising before you feel uncomfortably tired.

Ask Someone to Supervise You

Recruiting help from a personal trainer, physical therapist, or other fitness professional may help you craft a safe exercise strategy that works for you and your intolerance.

For mild exercise that will invigorate your body without pushing it too hard, try physical therapy sessions once or twice a week. Your physical therapist can help you set achievable goals without exhausting your system.

Now that you’re educated about exercise intolerance, watch out for any signs or symptoms during your practice, and most of all, exercise safely.