Myocardial infarction (MI), more commonly known as a heart attack, occurs when the narrowing or blockage of a blood vessel deprives the heart from receiving adequate blood flow. This injury can often result in sudden death by disrupting the electrical signaling of the heart. In patients that survive, however, the heart can undergo several changes that could collectively lead to impaired heart function. If left untreated, this progressive decline in function can result in heart failure, poor quality of life, and sudden death. It is important, therefore, to identify more effective strategies to prevent adverse changes in the heart and improve function after MI.
A recent study by Marschner and colleagues, published in PLOS ONE, found evidence that short-term exercise may have several beneficial effects on the heart. In the study, twenty-four three-month-old rats either underwent a surgery to model MI or a sham control surgery to account for any surgery-induced effects. Rats in the MI and sham groups were subsequently divided into the sedentary group or the trained group. The sedentary group did not undergo any exercise, whereas the trained rats had to exercise every day for forty minutes, four times a week. The training regimen started ninety-six hours after the surgery and lasted for a total of four weeks. Each rat’s heart function, levels of oxidative stress markers, and type 3 iodothyronine deiodinase (D3) activity were assessed. Elevated oxidative stress markers and D3 activity following MI have previously been reported in the literature.
In the current study, the authors found that MI surgery resulted in poor heart function, as evident by reduced blood output and an enlarged heart. Furthermore, MI injury was also associated with elevated levels of oxidative stress markers and D3 activity. Interestingly, however, MI rats that underwent short-term exercise training had significantly improved heart function, and lower levels of oxidative stress markers and D3 activity, compared to MI rats that were in the sedentary (no training) group. These findings suggest that the beneficial effects of exercise on heart function may be mediated through improved oxidative stress and lower D3 activity. Further validation is necessary to confirm these findings. Additional research will also be required to thoroughly investigate how short-term exercise may mediate oxidative stress levels and D3 activity, and how these changes may, in turn, improve heart function. Finally, these studies will also need to eventually be repeated in humans.
Written by Haisam Shah
Marschner RA, Banda P, Wajner SM, Markoski MM, Schaun M, Lehnen AM (2019) Short-term exercise training improves cardiac function associated to a better antioxidant response and lower type 3 iodothyronine deiodinase activity after myocardial infarction. PLoS ONE 14(9): e0222334. https://doi.org/10.1371/journal.pone.0222334
Image by Mabel Amber, still incognito… from Pixabay