ANATOMY
MUSCULOSKELETAL AND SOFT TISSUE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Motor unit recruitment begins with large units to small units
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Motor unit recruitment begins with small units to large units
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Motor unit recruitment depends on the amount of force being produced
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Motor unit recruitment recruits whatever is most excitable
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Detailed explanation-1: -The size principle states that motor units will be recruited in order of size from smallest to largest depending upon the intensity. When considering the various properties of the motor units this makes sense. The small units don’t produce much force, they are slow to act, and they are resistant to fatigue.
Detailed explanation-2: -Starting with the smallest motor units, progressively larger units are recruited with increasing strength of muscle contraction. The result is an orderly addition of sequentially larger and stronger motor units resulting in a smooth increase in muscle strength.
Detailed explanation-3: -The size principle states that as more force is needed, motor units are recruited in a precise order according to the magnitude of their force output, with small units being recruited first, thus exhibiting task-appropriate recruitment.
Detailed explanation-4: -Motor units are generally recruited in order of smallest to largest (from fewest fibers to most fibers) as contraction increases. This is known as Henneman’s Size Principle. The smaller the motor unit, the more precise the action of the muscle.