Effects of high-intensity interval versus continuous moderate-intensity aerobic exercise on apoptosis, oxidative stress and metabolism of the infarcted myocardium in a rat model

Abstract

The optimal aerobic exercise training (AET) protocol for patients following myocardial infarction (MI) has remained under debate. The present study therefore aimed to compare the effects of continuous moderate-intensity training (CMT) and high-intensity interval training (HIT) on cardiac functional recovery, and to investigate the potential associated mechanisms in a post-MI rat model. Female Sprague Dawley rats (8-10 weeks old) undergoing MI or sham surgery were subsequently submitted to CMT or HIT, or kept sedentary for eight weeks. Prior to and following AET, echocardiographic parameters and exercise capacity of the rats were measured. Western blotting was used to evaluate the levels of apoptosis and associated signaling pathway protein expression. The concentrations of biomarkers of oxidative stress were also determined by ELISA assay. Messenger (m)RNA levels and activity of the key enzymes for glycolysis and fatty acid oxidation, as well as the rate of adenosine triphosphate (ATP) synthesis, were also measured. Compared with the MI group, exercise capacity and cardiac function were significantly improved following AET, particularly following HIT. Left ventricular ejection fraction and fraction shortening were further improved in the MI-HIT group in comparison to that of the MI-CMT group. The two forms of AET almost equally attenuated apoptosis of the post-infarction myocardium. CMT and HIT also alleviated oxidative stress by decreasing the concentration of malondialdehyde and increasing the concentration of superoxide dismutase and glutathione peroxidase (GPx). In particular, HIT induced a greater increase in the concentration of GPx than that of CMT. AET, and HIT in particular, significantly increased the levels of mRNA and the maximal activity of phosphofructokinase-1 and carnitine palmitoyl transferase-1, as well as the maximal ratio of ATP synthesis. In addition, compared with the MI group, the expression of signaling proteins PI3K, Akt, p38mapk and AMPK was significantly altered in the MI-CMT and MI-HIT groups. HIT was superior to CMT in its ability to improve cardiac function and exercise capability in a post-MI rat model. HIT was also superior to CMT with regard to attenuating oxidative stress and improving glucolipid metabolism of the post-MI myocardium.

κ-opioid receptor is involved in the cardioprotection induced by exercise training

“…Furthermore, exercise training increases the phosphorylation of AMPK to regulate the metabolism of myocardial tissue [35,36]. In this study, in agreement with previous studies [42,43,44], all three exercise training protocols with different intensities elevated the phosphorylation of AMPK. In ischemic hearts, activation of AMPK is an adaptive response, and it stimulates ATP production, which protects myocardial tissue from anoxia [32,33,34].…”

FSTL1 as a Potential Mediator of Exercise-Induced Cardioprotection in Post-Myocardial Infarction Rats

“…Conversely, exercise would counteract the muscle atrophy10 and hence, improve post-MI recovery. Moreover, exercise may act directly on the myocardium111213 to improve the microenvironment of infarcted hearts.…”

Interval and continuous aerobic exercise training similarly increase cardiac function and autonomic modulation in infarcted mice

“…Although moderate-intensity continuous endurance ET (MICT) seems to be the most accepted and recommend type of exercise for cardiac rehabilitation programs (Mezzani et al, 2013), the optimal ET prescription to elicit maximal outcomes for MI is still under debate (Lu et al, 2015; Moreira et al, 2013). Indeed, evidence have been indicating some advantageous for MICT (Pinho et al, 2012).…”

“…Indeed, evidence have been indicating some advantageous for MICT (Pinho et al, 2012). Whereas, other data have been indicating that high-intensity interval ET (HIIT)—which is conceptually accepted as a relatively brief session of intermittent exercise that alternate among a high-intensity effort and a passive or active rest of the same or approximate duration— can elicit larger beneficial outcomes after MI, in comparison with MICT (Elliot et al, 2015; Keteyian et al, 2014; Lu et al, 2015; Maiorana, 2012). However, others experiments did not find differences between continuous or interval protocols of ET (Nunes et al, 2015; Pattyn et al, 2016; Tschentscher et al, 2016), indicating that more data about this specific issue are necessary.…”