I felt a sharp pain in my lower back.

我感到背的下部一阵剧痛。

There are two main forms of lower back pain: acute and chronic.

下背部的疼痛发主要有两种类型：急性和慢性。

I had acupuncture in my lower back.

我在后腰上做了针灸。

This exercise will work the muscles of the lower back.

这样的运动可以锻炼腰部的肌肉。

Peek-a-boo (lower back): Lie face down on the floor using your outstretched arms to support baby in front of you.

躲猫猫（锻炼后腰）：脸朝下，用你伸展的胳膊支撑住你前面的婴儿。