Although an individual person's distribution of skeletal muscle fiber types is primarily genetically determined, there exists some evidence that fiber types can change in response to exercise to a limited degree (ie. a slow glycolytic fiber can change to a fast oxidative fiber). If such a change were to occur, which of the following proteins MUST change in some manner as the transition from one muscle type to another occurs? A) actin B) troponin C) myosin D) Ca²⁺-ATPase

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Quizplus · Accepted Answer

Myosin is the motor protein responsible for muscle contraction, and different types of myosin are present in different muscle fiber types. Therefore, if a slow glycolytic fiber were to transition to a fast oxidative fiber, the myosin isoform present in the muscle would need to change to one that is better suited for oxidative metabolism. While changes in the other proteins listed may also occur during this transition, myosin is the most critical protein for determining muscle fiber type.

Although an Individual Person's Distribution of Skeletal Muscle Fiber Types