As one third of the heartbeat cycle is composed of contraction, In between the regions of heart, the muscle cells are innerve first, relax the last. Such that the inner wall that seperates the two ventricles has the longest cycle and the outer walls the shortest cycle. So, the cardiac muscles doesn't fatigue due to the time of relaxation.
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The Brainliest Answer!
Cardiac muscles get continuous supply of blood which keep the muscles activated all the time. In case of decrease of blood supply in heart, may lead to ache or could stop the heart functioning i.e. heart attack.
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