When It Comes To Intense Exercise, New Research Says Don't Overdo It

When it comes to prioritizing fitness, we're all hoping to keep our bodies and minds in shape while contributing to our overall well-being. And sometimes, enticed by the promise of a heart-pumping, fat-burning gym sesh, that means we may feel inclined to crank the intensity.

But according to a new review by the American Heart Association of over 300 studies, extreme intensity during endurance workouts may actually increase the risk of heart problems like cardiac arrest and heart attacks.

Generally speaking, risk for cardiac arrest or heart attack wasn't particularly high among people who run marathons or do other intense cardio, but the review zeroed in on some standout factors that appear to increase someone's risk.

For example, nearly 40% of the cardiac events reported by people who did triathlons were first-timers. This suggests they may have either had an unknown heart issue to begin with—or they hadn't trained properly. In addition to that, the research revealed half of cardiac events actually happened during the last mile of half or full marathons (AKA the mile everyone starts running as fast as they can toward the finish line).

Higher altitudes were found to increase the risk of cardiac events as well, but the AHA says that can be mitigated by taking at least a day to acclimate before intense exercise if you're in a new and higher area.

All that to say, this isn't meant to discourage a healthy fitness regimen but rather provide deeper insight to keep in mind. Barry A. Franklin, Ph.D., notes, "Like medicine, it is possible to underdose and overdose on exercise—more is not always better and can lead to cardiac events, particularly when performed by inactive, unfit individuals with known or undiagnosed heart disease."

Luckily, the AHA's review included some heart-healthy tips to remember when working out; namely, slowly building up the intensity of your workout regimen.

Warming up, for example, is a good way to get your heart rate up steadily. In the same way, cooling down afterward helps your heart slowly return to normal. And to steadily and safely improve your endurance, gradually increasing the length of your workouts by five to 10 minutes is a good way to do it.

When possible, environmental conditions like humidity, temperature, and altitude can put extra pressure on your heart. So, either lowering the intensity of workouts in those conditions or seeking out more optimal conditions (say, in a gym as opposed to outside) may help on those high heat days. And of course, above all else, heart-related symptoms like chest pain or pressure, shortness of breath, and lightheadedness are a sign you should stop your workout and call your doc.