Then comes a brief period of contraction, when the myosin heads are binding, and pulling, and releasing, over and over, and the muscle fibers contract.

然后是短暂的收缩，这时肌球蛋白头一遍又一遍地结合、拉动和释放，肌肉纤维收缩。

The economy may even shrink in a period of contraction or contract in a slowdown – get smaller – before it reaches a trough or bottoms out and starts to grow again.

经济甚至可能在收缩期收缩或在放缓期收缩——变得更小——然后才达到低谷或触底反弹并开始再次增长。