What Happens If You Exceed Your Maximum Heart Rate During Exercise?

It is possible to exceed your maximum recommended heart rate for cardiovascular exercise - but it's certainly not recommended. Doing so is especially risky if you have a health condition or take medication. Your best bet when determining how high you should push your heart rate during exercise is to consult a doctor.

Significance

Your recommended target heart-rate zone is 50 to 85 percent of your maximum heart rate. Exceeding 85 percent of your maximum heart rate can be dangerous to your health, as exercising at an extreme intensity is associated with an increased risk for a cardiac event, according to a 2002 study published in the "Canadian Medical Association Journal." The researchers found that exceeding the 85 percent recommendation leads to poor heart-rate recovery, meaning it takes longer for heart rates to return to normal. Heart-rate recovery is a measure of cardiovascular fitness. The study also found increased incidence of non-sustained ventricular tachycardia and ST-segment depression among people exceeding the 85 percent recommendation, both of which are indicators of increased risk for cardiac mortality.

Risks

If you don't have coronary artery disease or risk factors for a heart attack, it is possible to go over your recommended heart rate without injury. However, it's still not a good idea because you are more likely to suffer sore joints and muscles if you do so and it raises your risk for a musculo-skeletal injury. Exercising above 85 percent of your maximum heart rate also puts you at risk for over-training. When you over-train, the systems in your body get weaker instead of stronger, which leads to increased fatigue and decreased performance. You also are more prone to injury and illness when you over-train.

Theories

While you want to avoid going over that 85 percent marker, finding your maximum heart rate is not as simple as it seems. The standard formula of 220 minus age is problematic for many reasons. The formula does not take into account several important factors, including fitness level, sex, leg strength and health. Also, the standard formula's validity has never actually been established for use among older adults, according to a 2001 study published in the "Journal of the American College of Cardiology." The researchers say the formula tends to underestimate heart rate maximum in older adults. And they say a better formula for healthy adults is 208 minus the result of .7 times age.

Considerations

It's always important to consult a doctor before staring any new exercise program, especially if it is strenuous. In some cases, a visit to the doctor is especially important before engaging in activities that will raise your heart rate to the top of the recommended cardiovascular zone for your age. Get an exercise stress test before you do any sort of vigorous exercise if you are older than 40 and have not exercised vigorously for two or more years, have even mild high blood pressure, have a family history of heart attacks before the age of 50 or have blood cholesterol that is higher than 220 mg, according to the "Encyclopedia of Heart Diseases," by M. I. Gabriel Khan. The test is an important tool for diagnosing coronary artery disease.