With a lake at the base, he could afford to build up speed.

And don't let yourself build up speed, in case I have to stop suddenly.

It turned in a tight circle, pounded the air a few times to build up speed, and came back.

I guess he couldn't build up enough speed to get it done once and for all.

They moved slowly at first, but soon built up speed.

A good way to build up speed is to do pyramid training.

It takes him a long time to build up speed.

"They just build up speed in the water and glide a little way."

No, what limits how fast we can build up speed is our own bodies.

Ships must build up speed, their initial movement is slow.