bulk up

柯林斯词典

bulk up (bulking,bulked,bulks)

1. PHRASAL VERB If someone bulks up or if they bulk up their body, they put on weight in the form of extra muscle. 使变粗壮; 变粗壮
They feel I need to bulk up, and to improve my upper body strength. 他们觉得我需要变粗壮些，并增强上身的力量。
My friend is obsessed with going to the gym and has really bulked up her arms. 我朋友迷上了去健身房，她确实把胳膊练得粗壮了。