Disorders like atrial fibrillation and other rhythm disorders may be particularly advantaged by improvements to calcium management induced by HIIT:
“The interval training also significantly improved the rats' conditioning. After the training period, their fitness level was actually better than that of the untrained rats that hadn’t had a heart attack,” says Stølen.
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“We found that interval training improves a number of mechanisms that allow calcium to be pumped out of the cells and stored more efficiently inside the cells. The leakage from the calcium stores inside the cells also stopped in the interval-trained rats,” says Stølen.
The effect was clear when the researchers tried to induce ventricular fibrillation in the diseased rat hearts: they only succeeded at this in one of nine animals that had completed interval training. By comparison, they had no problems inducing fibrillation in all the rats with heart failure who had not exercised.