It is important to realize that one joint cannot be mobile if the one above or below is not stable. I often see this in the back squat. It may appear that someone has tight hips because they cannot achieve a parallel squat.
They use all of your cues to keep the chest up, sit back, track the knees over the side of the foot, etc. and they just cannot get low.
At this point I would tell them to hop on the foam roller and watch them struggle. Anyone who has tight hips is in a world of hate rolling out their glutes. Along with rolling, the person does hip mobility drills so that they can get to optimal depth in the squat.
A few weeks go by and nothing has changed. Weight cannot increase because the person cannot squat safely and efficiently. Frustration sits in because this person cannot make proper progress in the exercise.
But are the hips actually tight? Very often it is an unstable core that does not allow optimal squatting depth. The hips cannot be mobile if the core cannot stabilize.
A squat like this usually denotes a lack of core stability. The forward trunk lean is a solid indicator. But there are other ways to be sure.
My favorite drill to determine hip mobility versus core stability starts with a medicine ball on the ground. I line it up with the athlete’s heels, tell them to pick it up with their back straight and stand with it. The majority of the time they can get down to the ball and pick it up with an upright torso.
How come their squat depth is awful but they can pick up the med ball with great depth?
The number one reason for this is that there is no load on the core, eccentrically. When weak core muscles have to handle a load on the back for example, the hips assist in stabilization. When you take that load away, the hips can move freely since the core has nothing to work against.
There are a couple of additional ways to determine hip mobility versus core stability.
1. Use a body weight overhead squat to see if there are discrepancies in squat depth under load. It is not too often that there is but it is a quick way to find out.
2. Can the person hold a plank? A real plank. If the hips are all high/low then the core strength is not up to par.
3. Switch to goblet squats. Holding the kettlebell in front of the body often allows squatters to get deep unlike back squats. If the hips get low, the core needs some work.
4. Use a piriformis/glute stretch to see the flexibility in the hips. Do not stretch athletes if you are not comfortable doing it first and foremost. If the hips create a lot of resistance then they need some mobility/ flexibility work.
This is not the end all be all list but there are a few pieces of information that they provide. It is very frustrating for someone to constantly work towards a goal only to find out that the goal was wrong.
If someone has good hips, do not continue to work on them. Determining this information is necessary before any corrective exercise is implemented.
Figure out the difference between core stability needs and hip mobility needs to achieve the deep squat that is necessary for optimal performance.