"High knees" refers to a fitness exercise where you lift your knees up towards your chest while standing or running.
Sentences with «high knees»
I love styling high knee boots with a chunky sweater! (couturezilla.com)
Every couple of minutes or so, run with higher knees for 30 seconds or with a longer stride, pump your arms harder, or twist through your torso more. (mindbodygreen.com)
These are like doing high knees in a plank position. (pumpsandiron.com)