Q:

Take up a sport

I have come across a collocation dictionary from oxford(actually surfing the site at the moment) and they exemplify this collocation:

I need to take up a sport to get fit.

Does do a sport=take up a sport mean the same thing?

A:

Not necessarily. Take up a sport means you weren't doing it before, but now you decided you want to do it, so you started to do it. To do a sport usually means you already have started it. 

