Ventricular and autonomic benefits of exercise training persist after detraining in infarcted rats

We evaluate the effects of detraining (DT, for 1 month) on the left ventricular (LV) remodeling and function, hemodynamic and baroreflex sensitivity (BRS), as well as on mortality rate of infarcted (MI) rats after 3 months of exercise training (ET, 50-70 % of VO₂max). Male Wistar rats were divided into five groups: control (C, n = 10), untrained-infarcted (UI, n = 15), trained-infarcted (TI, n = 12), untrained-infarcted plus 1 month (UI-1, n = 15) and detrained-infarcted 1 month (DI-1, n = 15). LV function was evaluated by echocardiography at the initial and final of the protocols. After following, ET and/or DT protocols, hemodynamic and BRS [by tachycardic (TR) and bradycardic (BR) responses] were assessed. TI group displayed increased VO2max in comparison with UI and DI-1 groups; however, DI-1 values remained increased compared to UI-1 group. MI area was reduced by ET and maintained after DT. Ejection fraction (TI = 60 ± 2 and DI-1 = 61 ± 2 % vs. UI = 41 ± 1 and UI-1 = 37 ± 3 %), E/A ratio (TI = 1.6 ± 0.1 and DI-1 = 1.9 ± 0.1 vs. UI = 2.9 ± 0.2 and UI-1 = 2.9 ± 0.3), TR (TI = 3.3 ± 0.3 and DI-1 = 3.3 ± 0.4 vs. UI = 1.7 ± 0.1 and UI-1 = 1.6 ± 0.1 bpm/mmHg) and BR (TI = -2.2 ± 0.1 and DI-1 = -2.0 ± 0.1 vs. UI = -1.3 ± 0.09 and UI-1 = -1.2 ± 0.09 bpm/mmHg) were improved by ET and maintained after DT in comparison with untrained rats. These changes resulted in mortality reduction in the TI (8 %) and DI-1 groups (13 %) compared with the UI (46 %) and UI-1 (53 %) groups. These findings indicate that ET is not only an effective tool in the management of cardiovascular and autonomic MI derangements, but also that these positive changes were maintained even after 1 month of DT in rats.