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Correct Answer: isotonic contractions
to answer the question about which function of skeletal muscles impacts body movement, we must consider the types of muscle contractions and how they contribute to motion.
isotonic contractions are the correct answer because they directly facilitate body movement by allowing muscles to change length during contraction, maintaining constant tension. there are two main types of isotonic contractions: concentric and eccentric. during concentric contractions, the muscle fibers shorten as they contract. this type of contraction is typically associated with lifting or pulling actions, where the muscle shortens as it exerts force against a load. for example, when you perform a bicep curl, the biceps muscle shortens as you lift the weight towards your shoulder.
on the other hand, eccentric contractions occur when the muscle fibers lengthen while still producing force. this usually happens during controlled lowering movements. for instance, when you lower the same weight during a bicep curl, your biceps are engaging in an eccentric contraction. although the muscle is lengthening, it is still actively controlling the motion against gravity. eccentric contractions are crucial for movements that require controlled slowing or resisting forces, such as walking down a hill or lowering a heavy object.
isometric contractions, while also important in the overall function of muscles, do not contribute directly to body movement in terms of changing the position of the limbs. in isometric contractions, the muscles develop tension while remaining at a constant length. this type of contraction is crucial for maintaining posture or stabilizing joints but does not result in actual movement of body parts relative to each other.
therefore, isotonic contractions are fundamental for most dynamic physical activities, including walking, running, lifting, and throwing. by facilitating the shortening and lengthening of muscles, isotonic contractions allow the body to move and adapt to loads efficiently and effectively.
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