Pumping iron does a heart good—and MRI proves it

While the benefits of resistance training on musculoskeletal health are on daily display in any weightlifting room, the question of how much good all those sets and reps do for the heart has been open. Now comes an imaging-based answer from Germany, where researchers using MRI found measurable cardiac changes in a randomized group of novice male “gym rats” after they’d worked out regularly for around half a year.

Radiologist Michael Scharf of Friedrich-Alexander University Erlangen-Nürnberg and colleagues randomly assigned 40 untrained middle-aged men to a high-intensity resistance-training (HIRT) group and 40 roughly matched participants to an inactive control group.

HIRT is based on the performing of exercises in single sets to the point of full, can-do-no-more failure.

For the study, the HIRT group exercised two to three days a week for 22 weeks. The regimen engaged each of the major muscle groups common to targeting by recreational lifters.

By the end of the program, the researchers found indexed left ventricular (LV) and right ventricular (RV) volume and mass had significantly increased in the experimental group.

Further, mean LV and RV remodeling indices in the HIRT group did not alter with training, “indicating balanced cardiac adaption,” the authors note.

Also, indexed LV and RV stroke volume significantly increased with HIRT, while myocardial strain and strain rates did not change following resistance exercise.

The authors conclude that a faithfully followed HIRT workout routine can lead to marked physiological improvements in cardiac atrial and ventricular morphologic characteristics and function in previously untrained men.

“As our study comprises a relatively broad age range with a relevant distribution of physical characteristics, risk factor profile and fitness level, we hypothesize that physiologic cardiac adaptions to HIRT found in our investigation are generalizable to a large part of the population,” they write.

The study is available in full for free.