High-intensity interval training improved functional capacity and increased soleus muscle energy metabolism enzymes in infarcted rats without altering cardiac remodeling.
Does high-intensity interval training improve functional capacity and cardiac remodeling in rats after long-term myocardial infarction?
High-intensity interval training improves functional capacity and skeletal muscle energy metabolism in infarcted rats, independent of changes in cardiac remodeling.
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Abstract Introduction Aerobic training is beneficial in cardiovascular rehabilitation. However, the effects of high-intensity interval training (HIIT) on cardiac remodeling and skeletal muscle after myocardial infarction (MI) are not fully understood. In this study, we evaluated the effects of HIIT on functional capacity and cardiac remodeling in rats after long-term MI. Skeletal muscle trophicity, oxidative stress markers, and activity of the enzymes involved in energy metabolism were assessed in the soleus. Methods Three months after MI induction, Wistar rats were divided into Sham (n=20), MI (n=9), and MI-HIIT (n=9) groups. The rats were trained three times a week for three months on a treadmill. Maximum functional capacity was assessed by the exercise tolerance test, performed before, after 45 days and at the end of the training period. Training sessions were 3 minutes at 60% maximum functional capacity, followed by 4 minutes at 85%. This sequence was repeated seven times, totaling 49 min per session. Cardiac evaluation was performed by echocardiography at the end of the protocol. Oxidative stress and energy metabolism markers were analyzed by spectrophotometry and muscle trophism by morphometry in hematoxylin and eosin-stained histological slides. Statistical analysis: ANOVA and Tukey or Kruskal-Wallis. Results HIIT was safe. Functional capacity was higher in MI-HIIT than Sham and MI groups at the end of the protocol (See figure). MI-HIIT and MI had left ventricular (LV) dilation and hypertrophy with systolic dysfunction before exercise. At the end of the protocol, MI-HIIT and MI maintained the same pattern of cardiac remodeling and systolic dysfunction, which were unchanged by exercise (See table). MI size and soleus muscle fiber cross-sectional area did not differ between groups. Catalase activity was lower in MI and MI-HIIT than Sham. Superoxide dismutase and glutathione peroxidase activities and lipid hydroperoxide concentration did not differ between groups. HIIT increased pyruvate kinase, citrate synthase and carnitine palmitoyltransferase 1 activity compared to MI and Sham (See table). Conclusion High-intensity interval training improves functional capacity, regardless of changes in cardiac remodeling and left ventricular function in infarcted rats. Improvement in physical capacity is accompanied by increased activity of enzymes involved in soleus muscle energy metabolism.
Pontes et al. (Sat,) reported a other. High-intensity interval training improved functional capacity and increased soleus muscle energy metabolism enzymes in infarcted rats without altering cardiac remodeling.