To demonstrate muscle fatigue, a student held an 8-lb dumbbell in her hand and a

Question

To demonstrate muscle fatigue, a student held an 8-lb dumbbell in her hand and abducted her upper limb so that it was parallel to the floor. After 45 seconds, she was having trouble holding that position so she rotated her hand 90 degrees. By doing this she was able to hold the dumbbell in position for an additional 20 seconds. Which of the following statements best explains why the student could do this? The load was reduced. Different motor units were contracting while others were relaxing. The resistance to contraction was reduced. Muscles began to contract rather than. The change in position provided a greater range of motion at the shoulder.

Explanation / Answer

Answer:Muscle began to contract isotonically rather than isometrically. In isotonic contraction, muscle shortens to overcome resistance. As muscle shortens, at least one joint moves, and body movement occurs.Here the tension developed is same but length of muscle changed by moving hand at 90 degree.It helped in overcoming resistance caused due to isometric contraction.

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