Impact of a High-Intensity Training on Ventricular Function in Rats After Acute Myocardial Infarction

Abstract

BackgroundPhysical exercise should be part of the treatment of post-acute myocardial infarction (AMI) patients.ObjectiveTo evaluate the effects of two training prescription models (continuous x interval) and its impact on ventricular function in rats after AMI with normal ventricular function.MethodsForty Wistar rats were evaluated by echocardiography 21 days after the AMI. Those with LVEF = 50% (n = 29) were included in the study and randomized to control group (CG n = 10), continuous training group (CTG n = 9) or interval training group (ITG, n = 10). Then, a swimming test with control of lactate production was performed. Based on its result, the lactate threshold (LT) was established to define the training intensities. After six weeks, the animals were reassessed by echocardiography and lactate production. Outcome measures were end-diastolic diameter (EDD), end-systolic diameter (ESD), left ventricular ejection fraction (LVEF, %) lactate at rest, lactate without overload, and lactate with 12g and 13.5g of additional load. Group comparisons of quantitative variables of the study were performed by one-factor analysis of variance (ANOVA). The Newman-Keuls test was used for multiple comparisons of the groups. Within-group comparisons of dependent variables between the two training protocols were performed by Student's t-test. Normality of the variables was tested by the Shapiro-Wilks test. Values of p < 0.05 indicated statistical significance.ResultsEDD, ESD, and LVEF before and after the training period were similar in within-group comparisons. However, EDD was significantly different (p=0.008) in the CG. Significant differences were found for L12g (p=0.002) and L13.5g (p = 0.032) in the ITG, and for L12g (p = 0.014) in the CG. No differences were found in the echocardiographic parameters between the groups. Significant differences were found in lactate without overload (p = 0.016) and L12 (p = 0.031) in the second assessment compared with the first, and between the groups - ITG vs. CG (p = 0.019) and CTG vs. CG (p = 0.035).ConclusionBoth methods produced a training effect without altering ventricular function.

Non-Pharmacological Treatment of Cardiovascular Disease | Importance of Physical Exercise

“…The regular practice of exercises results in several benefits, such as increased functional capacity and improved body composition, insulin resistance, endothelial function, arterial hypertension, antioxidant status, and quality of life. 3-9…”

“…In articles recently published in this journal, the role of exercise and its molecular mechanisms of action have been evaluated in different heart disease experimental models. 3,5,11-13 The beneficial effects on cardiac remodeling have been frequently observed, such as attenuation of myocardial hypertrophy and left ventricular dysfunction. 7,14 However, unexpected results have drawn attention to the need for better clarification of the subject.…”

High-Intensity Interval Training for Early Post-Acute Myocardial Infarction - A Promising Approach for Rats, but what about Human Beings?

“…In this journal issue, Winter et al 10 report information on the effects of HIIT on functional capacity and ventricular function in 29 Wistar rats after AMI. On day 21 after the event, the animals were randomized to control group (n = 10), or to undergo continuous training (n = 9) or HIIT (n = 10).…”

“…On the other hand, the body of scientific knowledge is not sufficiently consistent to definitely recommend HIIT as a training modality for early post-AMI patients. Anyway Winter et al, 10 in their investigation on laboratory animals, take an important step towards an effective alternative for cardiac rehabilitation programs in this group of patients.…”