The Na+/K(+)-pump protects muscle excitability and contractility during exercise.

In skeletal muscle, the concentration of Na+/K(+)-pumps is high and increases through training. In isolated muscles, contractile endurance depends in part on Na+/K(+)-pump concentration. Exercise leads to rundown of Na+/K(+)-gradients, compound action potentials, and force. Early and efficient activation of the Na+/K(+)-pump, however, protects excitability and contractility.