This exercise will work the muscles of the lower back.

这样的运动可以锻炼腰部的肌肉。

《牛津词典》

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The culprit may be weak back muscles, the type of surface on which you run, the shoes you wear, or the length of your running stride.

其原因可能是背部肌肉太弱，也可能是你奔跑的路面有问题，还可能是你穿的鞋不合适，也许是因为你的步幅不对。

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This temporarily blocks signals that pass through the nerves to the muscles of the body and back to the brain.

VOA: special.2009.01.06

It might not be easy to imagine Mr Romney with a small pipe, oversized, tattooed muscles, glugging back a can of spinach.

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Muscle activation: This phase involves four-second contractions of major muscle groups in the lower body, including calves, quadriceps, hamstrings, hip flexors, groin, and hip and lower back muscles to help athletes increase awareness of individual muscle groups.

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"By the time you are done with me, your back muscles are going to be in a heap of pain, " the colon went on.

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