loosen up
phrasal verbUK /ˈluːsən ʌp/
US /ˈluːsən ʌp/
To relax and stop being stiff or worried.
The coach told the players to loosen up before the game.
RELATED WORDS
OTHER MEANINGS
2. To make something less tight.
He loosened up his shoelaces after the long run.
3. To become less strict or firm about rules.
The teacher loosened up on homework during the holidays.
4. To stretch your muscles to get ready for exercise.
She loosened up her arms before lifting the weights.