During intense exercise, can a muscle cell use fat as a concentrated source of chemical energy? explain.

Yes, during intense exercise, muscles cell may use fat as a concentrated source of chemical energy. When oxygen is present, the fatty acid chains containing most of the energy of a fat are oxidized and fed into the citric acid cycle and the electron transport chain. Nonetheless, during intense exercise, oxygen is scarce in muscle cells, so ATP must be generated by glycolysis alone. 

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