Laird Harrison

June 08, 2012

June 8, 2012 — Men's right ventricles get bigger with endurance training but stay in proportion to their left ventricles, researchers reported here at the American College of Sports Medicine (ACSM) 59th Annual Meeting.

"There has been some thought that highly trained athletes are more susceptible to enlarged hearts because their training can mask underlying conditions," lead author Angela Spence, an exercise science researcher at the University of Western Australia, in Perth, Australia, told Medscape Medical News.

Spence and her colleagues wanted to see whether this concern was warranted in people who were not competitive athletes.

"Using a healthy male population we did not see any negative effect," she said.

After 6 months of endurance training, right ventricle mass increased by 3.1 g in an eccentric pattern, according to the researchers. They used magnetic resonance imaging (MRI) and echocardiography to compare right ventricle changes in endurance training and resistance training.

Previous research has found a similar pattern in the left ventricle. However, this is the first prospective, longitudinal, randomized, controlled trial using MRI to look at the effects of endurance training on the right ventricle.

The researchers randomly assigned 10 young men to an endurance training program and 13 to a resistance training program. The mean age was 27.4 ± 1.1 years.

Both groups worked out 3 times a week under supervision. The endurance group walked or ran while the resistance group practiced Olympic weightlifting and assistance strength lifts, such as the deadlift and squat press.

The researchers used MRI to calculate right ventricular mass. They subtracted the volumes between the epicardial and endocardial borders and multiplied them by the slice thickness and the specific density of the myocardium.

They determined that the right ventricular mass increased from 35.5 ± 2.4 g to 37.6 ± 2.8 g in the endurance-trained men, a statistically significant difference (P < .05).

In the resistance-trained men, the right ventricular mass increased from 41.6 ± 2.2 g to 42.6 ± 2.1 g, but the change was not statistically significant.

The researchers also used MRI to calculate end-diastolic volume and end-systolic volume, ejection fraction, stroke volume, and cardiac output. They did not find statistically significant changes in these measures.

Not surprisingly, the participants' peak oxygen volume increased significantly (P < .05) with endurance, but not with resistance training. Strength increased in both groups, but more so in the resistance group than the endurance group (P < .001).

The researchers used speckle-tracking echocardiography to measure peak strain, peak systolic strain rate, peak early diastolic strain rate, and peak late diastolic strain rate. They found no significant differences, either between groups or from baseline to post-training.

They found that the ratio of left ventricular mass to right ventricular mass did not change with training.

Spence noted that the pattern of growth was eccentric rather than concentric. Some researchers have speculated that concentric thickening of the myocardial wall could result in a less efficient heart, she said.

Graeme Carrick-Ranson, PhD, an exercise physiologist from the University of Texas Southwestern in Dallas, told Medscape Medical News that he found the research reassuring.

"This expands on the idea that endurance training is beneficial," Dr. Carrick-Ranson said. "There are no negative effects on the heart. The adaptations we see are physiological and not pathological."

The study is important because the right ventricle has not gotten as much attention as the left in previous research, according to Dr. Carrick-Ranson .

"The focus has been on the left ventricle, because that's the main pumping engine," he said. "But the right ventricle is just as important, and we need to know whether it changes."

Neither Angela Spence nor Dr. Carrick-Ranson has disclosed any relevant financial relationships.

American College of Sports Medicine (ACSM) 59th Annual Meeting. Abstract #1125. Presented June 1, 2012.