When following a proper strength training protocol, you'll be doing lots of squatting and deadlifting. While learning these movements, we often lack the motor pattern proficiency to perform them perfectly. That means things wobble around. The spine doesn't always stay neutral, and the knees shake like a baby giraffe. This is all part of the process. We all fell off a bike the first time we climbed on, but eventually we got the hang of it. But in the meantime, we had some bumps and bruises to show for it. We bump and bruise a few places from improper movement, but one of the most common recipients from our poo poo patterns is the hips.
They ache, they grind, they click. It doesn't feel good. I've been there myself, especially after a hard training session. They need a little bit of love, and little bit of lube in there to make them happy again. Enter the Hip Airplane.
The Hip Airplane serves to restore proper function to the hips. They should be able to maximally internally rotate (point your knee inwards) and externally rotate (point knee outwards), without pulling your spine along with it. This is easy to coach with the Hip Airplane; just don't fall down. This also serves to get things moving in that stiff joint which can feel better in and of itself. So give it a shot, and give em some grease!