This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers. The control mechanism of muscle contraction generated by collective motion of molecular motors is elucidated from the perspective of variable-frequency regulation, and action potential with variable frequency is proposed as the control signal to directly regulate Ca2+ concentration and indirectly control isometric tension. Furthermore, the transfer function between stimulation frequency and Ca2+ concentration is deduced, and the frequency domain properties of muscle contraction are analyzed. Moreover the conception of “electro-muscular time constant” is defined to denote the minimum delay time from electric stimulation to muscle contraction. Finally, the experimental research aiming at the relation between tension and stimulation frequency of action potential is implemented to verify the proposed variable-frequency control mechanism, whose effectiveness is proved by good consistence between experimental and theoretical results.

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