Abstract 21236: Increased Extent of Myocardial Edema In Endurance Athletes Following Acute High-Intensity Interval Training: A Cardiovascular Magnetic Resonance (CMR) Study
Background: Markers of cardiac injury are elevated during intense exertion, and while high-intensity interval training is used in athletes to improve peak aerobic power (VO2peak), its impact upon the heart is not well understood. Myocardial edema reflects reversible injury and may be a substrate for rhythm conduction disturbances. Thus, we hypothesized that myocardial edema is a feature of high-intensity interval training, as visualized by T2-weighted CMR imaging.
Methods: 12 male endurance athletes (age 32±11 years) were prospectively recruited. LV function and T2-weighted imaging for visualizing edema was performed on a 1.5T MRI system, prior to and within an hour of interval training. High-intensity interval training was performed on a braked bicycle ergometer, where athletes completed 15 repetitions of cycling at maximal power output for 1 minute followed by 2 minutes of light recovery. Extent of myocardial edema was assessed quantitatively using semi-automated detection, where myocardial regions that had signal intensity (SI) above a threshold of twice the mean SI of skeletal muscle were considered to be edematous. Global edema was measured by normalizing myocardial SI to skeletal muscle SI, generating a T2-ratio.
Results: Extent of myocardial edema increased significantly following high-intensity interval training (37.1% vs. 17.0%, p=0.002) (Figure 1), and correlated with the percent change in LV function after exertion: LVESV (r=-0.692, p=0.013), LVSV (r=0.580, p=0.048) and LVEF (r=0.860, p<0.001). Global myocardial edema T2-ratio increased significantly following exertion (1.92 vs. 1.70, p<0.001).
Conclusion: We provide first evidence for increased extent of myocardial edema following high-intensity interval training. The extent of myocardial edema seems to be greater in athletic hearts with increased systolic function following exertion. Our findings may impact the implementation of high-intensity interval training in athletics.
- © 2010 by American Heart Association, Inc.