He always begins his lessons with a warm-up exercise.

他讲课前总是先让学生做预备练习题。

《牛津词典》

First let's do the warm-up exercise.

首先让我们做热身练习。

youdao

It's important to warm up before exercise.

在锻炼前做热身活动是很重要的。

youdao

Taking a warm bath or sitting by a fire or doing some exercise can also help the body warm up.

VOA: special.2009.12.30

And the fact that the lack of effort involved means you have to wrap up warm - or get very cold - serves as a reminder as to how much less exercise riding an electric bike involves.

BBC: Electric bikes: For people who don't cycle?