Myocardial infarction size and scar dimensions: the influence of activity

The purpose of this study was to determine myocardial infarct size and scar dimensions in experimentally infarcted rats that were randomly assigned to a moderate, mild, or no exercise condition after infarction.

Pretest-posttest control group design (experimental).

57 male Harlan Sprague Dawley rats between 62 to 64 days of age and weighing 220 to 290 gm at the onset of the study.

Infarction size, scar thickness, thinnest portion of scar.

Mild exercise versus moderate exercise versus no exercise.

No differences were found in infarct size, scar thickness, or thinnest portion of scar among the three groups.

This study establishes that treadmill exercise, begun after an appropriate period of recovery, does not necessarily increase infarct size or scar thinning in the rat model. Further, animal and human studies are needed to fully explore the benefits and hazards of cardiac rehabilitation or exercise testing before or soon after discharge.