fist
Clench your fists and move your arms upwards as you breathe out.
He clenched his fist, ready to strike out.
He clenched his fists and let out a scream when he won the match point.

SMART Vocabulary: related words and phrases

Gestures & gesturing
air punch
air quotes
bat
beckon
bird
blow someone a kissphrase
flip
flip someone off
flip/give someone the birdidiom
flourish
gesticulate
non-verbal
non-verbally
peace sign
pump someone's handidiom
shake
shrug
signing
tongue
wink