Effects of strength vs. endurance exercise on myocardial function and remodeling (1154.8)

Effects of strength vs. endurance training on myocardial function and remodeling in post‐MI rats Michael A. Garza, Emily A. Wason, John Q. Zhang, Department of Health and Kinesiology, The University of Texas at San Antonio TX After Myocardial Infarction (MI), increased plasma volume (PV) attributes to the progressive decline in cardiac function by exacerbating left ventricular (LV) dilation; however, compelling evidence suggests that endurance exercise training, despite eliciting a marked increase in PV, beneficially preserves post‐MI cardiac function. Contrarily, strength exercise training, which promotes concentric myocardial hypertrophy and has no effect on PV, may be more therapeutic in post‐MI applications; therefore, we investigated for the first time the effects of strength vs. endurance exercise training on myocardial function and remodeling in post‐MI rats. MI was surgically induced on 7‐wk‐old Sprague‐Dawley rats by ligation of the coronary artery. The survivors were assigned to 4 groups (n=8/group): Sham (no MI, no exercise), MI‐Sed (MI, no exercise), MI‐End (MI+endurance exercise), and MI‐St (MI+strength exercise). Endurance and strength exercise training using a rodent treadmill or an 85° inclined ladder, respectively, began 1‐wk post‐MI and lasted for 10‐wks. Although fractional shortening (FS%) was well preserved in both exercise trained groups compared to the MI‐Sed group, LV end‐diastolic dimension was significantly lower in the MI‐St group compared to the MI‐End group (1.03±0.01 vs. 1.21±0.01 cm, p<0.05). Furthermore, pressure‐volume analysis data illustrated that dP/dt max values were significantly higher in the MI‐St group compared to the MI‐End group. Our data indicate that strength training may be more beneficial than endurance training at preserving post‐MI cardiac function and attenuating LV dilation.