follow through

to complete the movement of hitting, kicking, or throwing a ball by continuing to move your arm or leg in the same direction:
You need to follow through more on your backhand.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの follow through の定義 © Cambridge University Press)

アメリカ英語辞典
to continue something until it is completed:
The city has raised the money for more teachers – now it has to follow through and hire them.

In sports, to follow through is to continue a swinging motion of the arms or legs when making a play:
You can’t drive the golf ball unless you follow through after hitting it.
(Cambridge Academic Content Dictionary からの follow through の定義 © Cambridge University Press)

- Cambridge Dictionary