These two sets of muscles -- the front and the back -- are said to act in opposition to each other.
These two sets of muscles -- the front and the back -- are said to act in opposition to each other.
这两组肌肉，正面的和背面的，称为相反运动肌肉。
These two sets of muscles -- the front and the back -- are said to act in opposition to each other.
这两组肌肉，正面的和背面的，称为相反运动肌肉。