# Moderate-Intensity Swimming Alleviates Oxidative Injury in Ischemic Heart
## 1 Introduction  
Cardiovascular diseases (CVDs) are the most challenging health problems that science is facing in this century. It is pivotal to understand the molecular and cellular nature of CVDs as treatment and prevention are based on this knowledge. A non-exhaustive list of CVDs includes cerebrovascular disease and coronary heart disease, which encompasses myocardial ischemia (MI) [1, 2]. Myocardial ischemia, in particular, is associated with, among other things, extensive oxidative damage to the myocardium. Oxidative damage often develops during the so-called reperfusion injury (RI) after MI, which further aggravates the outcome of ischemia [3]. Oxidative stress is one of the major pathological mechanisms in reperfusion injury, causing myocyte death, inflammation, and endothelial dysfunction. It is characterized by the increased levels of reactive oxygen species (ROS) that can ultimately lead to the deterioration of lipids, DNA, and proteins and eventually irreversible cardiomyocyte damage [4]. To eliminate oxidative damage, the evolutionary antioxidant defense system ensures the integrity of the body through enzymatic and non-enzymatic reactions. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), and other enzymes that scavenge ROS and prevent their buildup have developed into a complex enzymatic antioxidant system in cells [5]. In addition to determining the degree of harm, oxidative stress markers as well as antioxidant enzymes can also be valuable as particular biomarkers in diagnostic and prognostic procedures. Likewise, cardiac biomarkers such as B-type natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) serve as reliableindicators for cardiac insult [6; 7]. To tackle cardiovascular-related challenges, we need to be aware of the fact that lifestyle habits are the pillars of cardiovascular health, hence, longevity. As sedentary lifestyle has been identified as a major risk factor for cardiovascular disease, it goes without saying that regular physical activity has long been shown to be an effective way to reduce cardiovascular mortality and morbidity. Exercise is known to improve blood flow to the heart and lower blood pressure and has also been shown to have antioxidant and cholesterol-lowering effects [8]. Exercise, by enhancing the function of antioxidant enzyme systems, can contribute to the improvement in adverse parameters following infarction [9; 10]. Several types of exercise, e.g., treadmill training or voluntary wheel running, have been shown to have beneficial effects on the heart after MI, due to the elevation in antioxidant enzymes [11; 12; 13]. The wide-ranging benefits of physical activity have been known for a long time, but it is important to emphasize that besides being an exceptional treatment option, it has an outstanding potential in the prevention of life-threatening health conditions as well.  
This article underscores the pivotal role of ongoing cardiovascular research in advancing our knowledge of myocardial ischemia and emphasizes the significance of exercise as a potent preventive strategy. We hypothesized that exercise protocol before infarction may be effective in alleviating the pathological processes that result from myocardial injury. Consequently, our research aimed to apply swimming as a non-pharmacological prevention method in non-invasively induced MI. The objective of the present study was to clarify how our exercise protocol affects cardiac biomarkers, antioxidants, and oxidative markers in the heart and systemically after MI/RI.