bulk up

The actor had to bulk up significantly to play the role of the superhero.

(Chinese) 为了扮演超级英雄这个角色，那位演员不得不大幅增加肌肉量。

He started eating more protein because he wanted to bulk up before the football season.

(Chinese) 他开始摄入更多蛋白质，因为他想在足球赛季开始前增加体重。