Safe Max Heart Beat Rate During Rigorous Exercise

Measuring your heart rate is a good way to monitor your exercise intensity and ensure that you are exercising safely. Your maximum heart rate depends on your age and fitness level. The Centers for Disease Control and Prevention defines vigorous exercise as 70 to 85 percent of your maximum heart rate. The Cleveland Clinic advises against exceeding 85 percent, as this could cause cardiovascular problems and added risk of injury. However, if you have no health conditions, exercising at a higher intensity for short bursts during interval training can be an effective way to improve your fitness level.

Calculating Maximum and Target Heart Rates

The best way to accurately determine your maximum heart rate is clinical testing, usually by using a treadmill. However, you can estimate it by subtracting your age from 220; some experts recommend that women use a starting figure of 226. For example, a 40-year-old man's maximum heart rate will be roughly 180. Your target heart rate for vigorous exercise should be 70 to 85 percent of this figure, or 126 to 153 beats per minute. When exercising, stop occasionally and check your pulse to determine if you're exercising in your target zone. Alternatively, wear a heart-rate monitor. Your pulse should return to its resting rate about 10 minutes after you finish exercising.

Lactate Threshold

As your heart rate increases, your body will reach its lactate, or anaerobic, threshold. This is the point at which your body can't supply adequate oxygen to your muscles. Lactic acid begins to build up in your blood, your muscle carbohydrate stores begin to get depleted and you can fatigue rapidly. Although this isn't unsafe, you'll be unable to sustain exercise for more than a few minutes at this level. Sports coach Brian Mac advises that this stage usually occurs at 50 to 90 percent of maximum heart rate, and increases with training. He cautions that only the very fit can train at more than 90 percent of their maximum heart rate, and then only for short bursts.

Risks of Overexertion

According to the Cleveland Clinic, exercising at more than 85 percent of your maximum heart rate can increase your risk of cardiovascular and orthopedic problems, and produces minimal added benefits. The American Council on Exercise advises that you should exceed 90 percent of your maximum heart rate only if you're an experienced exerciser or supervised by a trained health professional, as you could become extremely fatigued and develop added risk of injury. Use your target heart rate as a guide, but slow down if you feel you can't breathe comfortably and are overexerting yourself.

Ventricular Tachycardia

If you have a heart condition, you might be at risk of ventricular tachycardia. This is an unhealthy elevated heart rate, when the heart's ventricles contract before they can completely fill with blood. Symptoms include dizziness, light-headedness and unconsciousness, and the condition can lead to a heart attack. If you think you're at risk, talk to your doctor before beginning a vigorous exercise routine.

Other Considerations

If you're pregnant, obese, have high cholesterol, high blood pressure, diabetes, a heart condition or other health problems, talk to your doctor about reaching your exercise goals. You might be advised to modify your target heart rate and take extra precautions. If you take beta blockers, or certain other medicines, you might not be able to reach your target heart rate. Beta blockers slow your heart rate.