Exercise, stimulation and type transformation of skeletal muscle.

Although chronic electrical stimulation of muscles over a period of weeks produces a profound slowing of their contractile characteristics, such changes do not form part of the response to endurance training. The reasons for this apparent anomaly are contained in the organization of the final common pathway of the motor system and the orderly way in which it is recruited. There is also a need to introduce the notion of thresholds for the transitions from one fibre type to another. The conceptual framework that emerges from these ideas enables us to take a scientific approach to the problems posed by the clinical applications of electrical stimulation.