All my muscles were tensing for a fight.

我浑身的肌肉都绷紧了，准备进行一场搏击。

I went back to my seat, tensing up inside.

我回到自己的座位上，内心很紧张。

Tensing opposing muscles is a major cause of tension.

拉紧不利的肌肉是紧张的主要原因。

You can see her tensing up when she's saying that. Karma?

你可以看得出她说的时候是很紧张的，报应？

Lengthening and broadening them does not mean tensing them.

延长展宽并不意味着使双脚紧张。