noun
practice swing
Refers to swinging a sword, bat, racket, etc. without hitting a ball or target, as a warm-up or form practice. Common in sports and martial arts.
バッターボックスに入る前に素振りをする。
I take practice swings before stepping into the batter's box.
剣道の稽古で素振りを百回やった。
I did one hundred practice swings in kendo training.