limber up(to stretch one's muscles to make them more limber) verb [UK: ˈlɪm.bə(r) ʌp] [US: ˈlɪm.bər ʌp]
stretch [stretched, stretching, stretches](to extend one’s limbs or body in order to stretch the muscles) verb [UK: stretʃ] [US: ˈstretʃ]John was stretching. = John stretchade.