1、站立，手握哑铃
2、90度弯曲手臂，手肘贴着身体
3、保持上臂贴着身体向外张开手臂
4、返回起始位置
5、External rotation, dumbbell
英文描述：
Stand upright with one dumbbell in hand. Flex the elbow to 90 degrees and keep it close to your side.
Externally rotate to the maximal range of motion that you can get without rotating the trunk.
Keep the head and trunk still.
Keep the wrist in line with the forearm at all time.
