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Involuntary muscles never get inactives. They are always keep working with or without our concern. The best example is heart muscle which pump the blood, they are always active.
Involuntary muscles or muscles that are located on your axial skeleton never get fatigue. Your heart is an example of an involuntary muscle. These muscles are not controlled by the central nervous system. They move on their own and don't require your brain to tell them to function. These muscles are made of striated and cardiac (only the heart) muscle types. These types of muscle contain mitochondria that stores energy for contraction. Involuntary muscles are very important muscle because they keep our bodies functioning.
no it is a cardic muscle in our heart which gets never tired 
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