However, quiet expiration is a passive process, as it requires no muscular contraction.

然而，安静呼气是一个被动的过程，因为它不需要肌肉收缩。

Specifically, our cells need the oxygen to make ATP, which then provides energy for work: for example, muscular contraction.

具体来说，我们的细胞需要氧气来制造ATP，然后ATP为工作提供能量：例如，肌肉收缩。