Exercise makes the heart stronger and healthier, but in different sport-specific ways.

Scientists are aware that regular exercise alters the appearance, structure, and performance of the heart. The left ventricle, in particular, becomes bigger and stronger with regular cardiovascular or aerobic exercise. It is the part of the heart that twists and recoils, pumping oxygen-rich blood from the lungs into the body. Exercise improves the efficiency, speed, and performance of left ventricular mechanics. More research has been emerging, exploring how the hearts of athletes physically change to adapt to their respective disciplines.

In 2014, a study published in the American Journal of Cardiology examined the hearts of 947 elite athletes representing 27 sports via echocardiography. They found that endurance cyclists, rowers, and swimmers had the largest left ventricular cavities and wall thickness. The hearts of weightlifters and wrestlers had thicker walls relative to changes in cavity size.

Back in 2008, a study published in the Journal of Applied Physiology compared how endurance training and strength training affected the heart. The researchers used echocardiography to compare the hearts of test subjects after a 90-day period of regular training. While the hearts of both groups showed significant increases in size, the left and right ventricles of the endurance athletes expanded and the heart muscles of the strength athletes thickened around their left ventricles. The relaxation of the heart muscles between beats increased in the endurance athletes more so than in the strength athletes.

A 2015 study published in the Journal of the American Society of Echocardiography found that competitive rowers, who require both power and endurance, built greater left ventricular muscle mass than runners. This suggests that the heart of a rower relies on mass-dependent diastolic function (referring to the phase of the heartbeat when the heart relaxes and expands to fill the chambers with blood), making it strong but possibly less nimble than the heart of a runner.

A more recent study from 2018 published in Frontiers of Physiology found that runners and swimmers have made their hearts stronger in different ways. Runners and swimmers both engage in cardiovascular exercises that have relatively similar demands on the athletes as well as benefits. The researchers found that their heart rates were around 50 bpm, significantly lower than those of people who didn’t exercise, but the runners had slightly lower heart rates.

Runners also exhibited faster diastolic performance of their left ventricles, meaning that theirs untwisted faster and their hearts filled with blood earlier compared to the swimmers. However, this does not conclude that runners are the physically superior athletes. Swimmers exercise in horizontal positions, so their hearts do not have to fight gravity. Meanwhile, the hearts of runners must compensate in the upright position. In addition, the study was conducted while the test subjects were at rest after exercising. It did not paint a clear picture of how the hearts of these athletes actually perform during the activities. It would also be interesting to examine triathletes who are subjected to varying training loads in their multiple disciplines.

Any type of exercise is better than none. To get the most health benefits out of physical activity, planning your week to include both aerobic exercise and strength or resistance training is recommended.

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Photo Credits:

Images are from InHealth, Speedo, Run Singapore, and Realbuzz.