Intense Exercise Could Have An Unexpected Effect On Your Heart Health

Exercise is just one of the factors that drive longevity, and it can help the heart by improving its ability to pump blood, and regulating blood pressure and heart rate. While regular exercise itself is good for the heart and other parts of the circulatory system, the intensity of your workouts also matters. For some people, the term "intense exercise" is often synonymous with distance running and endurance events. Exercise intensity goes beyond these exact types of activities, and it can apply to any form of aerobic exercise at any amount. Despite the benefits of increasing exercise intensity over time, there are hazards associated with too much vigorous activity. In some cases, intense exercise may lead to changes in the heart muscle and its ability to properly function. These risks are greater in people who have underlying heart conditions, or those who regularly participate in extreme endurance events.

Intense exercise can look different for everyone depending on their individual fitness level. Your heart rate is a good indicator of how intense an exercise might be, since it looks at how fast your heart beats during an activity in relation to your maximum heart rate. More intense exercise falls within a zone between 70% and 85% of your maximum heart rate. Intense exercise can also cause rapid breathing, sweating, and difficulty talking during your workout. It's worth noting that any of these physiological effects can vary by fitness level. For example, a short run might feel relatively easy for an experienced athlete, but it may be much more intense for someone who is new to the activity.

Several studies have attempted to uncover the effects of intense exercise on the heart, with long-distance running at the forefront. According to a 2012 review in Missouri Medicine, chronic and excessive intense exercise were associated with possible changes in the heart such as artery calcification, arrhythmias, stiffening of the large artery, and diastolic dysfunction. There's also the possibility of developing "athlete's heart," which can cause a thickening of the left ventricle wall due to an increased demand to pump blood. According to the Cleveland Clinic, about 2% of athletes develop this condition, and it primarily affects people who engage in intense exercise for an hour or more on most days over the course of several years. Any endurance activity can contribute, including long-distance running, swimming, cycling, or rowing. Athlete's heart is not life-threatening, and the heart can return to its normal size after several months of reduced training.

It's also possible to experience a sudden cardiac event towards the end of an endurance event or shortly after. Yet, based on data collected between 1979 and 2010 reported in Sports Health, such events are extremely rare. Most of these cases occur in people with congenital heart diseases or preexisting heart conditions such as coronary artery disease.

Possible warning signs of a heart-related issue during intense exercise include chest pain, excessive fatigue, and sudden breathing difficulties. Experiencing these symptoms during an activity that's normally feasible for you is another sign of a potential problem. It's important to pause your training program and call a doctor right away for further evaluation.

Despite the risks associated with too much intense exercise, you shouldn't shy away from increasing the intensity of your workouts. Overall, the benefits of exercise outweigh possible risks for most people, including intense exercise. As a rule of thumb, adults need at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity exercise per week for overall health. These should be combined with strength-training exercises done at least two days per week (this can also help reduce the risks of muscles aging faster as you get older).

There may even be some heart benefits that endurance athletes experience compared to people who do not exercise at such intense levels. Notably, marathoners who develop heart disease may have better outcomes than those who don't run at all. Furthermore, a regular exercise program tends to decrease the risk of experiencing cardiac events after intense activities. The goal then, is to find the right balance of exercise intensity while protecting the heart, say the authors of the 2012 Missouri Medicine review. Incorporating rest days into your routine also helps muscles recover in between intense workouts.

One approach to vigorous exercise is to build the intensity on a gradual basis while staying in your target heart rate. While this is especially important for people who are new to an exercise program, the Mayo Clinic recommends a 10% increase in the amount you exercise per week as a safe rule of thumb for everyone. Finally, if you are considering endurance training for an event such as a marathon or a triathlon, it's definitely worth talking with a doctor ahead of time to make sure your heart is in good health.