The acetabulum is the cup shaped socket in the pelvis which forms the hip socket. The acetabulum typically faces slightly anteriorly, but a more lateral facing acetabulum (also known as acetabular retroversion) means that the femur will come into contact with the front of the acetabulum early during a squat stopping anterior pelvis rotation, this can cause issues in the pelvis or back issues as the spine overcompensates by rounding forward during the squat to maintain a stable center of gravity. To test if your having this issue lay on your back and hug each knee at a time, test if you can comfortably bring each thigh close to your body in a straight line with your body without pain, than test if you can go into deeper hip flexion by angling out your femur more so, if you couldn't perform deep hip flexion with your leg in line with your body or you couldn’t without pain you may have acetabular retroversion and/or a deeper hip socket which may be causing issues while squatting, if you could go to deeper hip flexion with your femur more angled outwards you likely will be better of squatting with your feet facing more outwards and a slightly wider stance, especially whilst under heavy loads. If you force yourself into a squat where the femur is coming in contact with the acetabulum too often, especially while under load, the tissues surrounding the joint can become irritated, if this continues the constant contact of the femur on the acetabulum can cause bone growth on the acetabulum this will further intensify joint contact and lead to more pain and potentially tearing of the labrum.

Squatting with and without load and recording from multiple angles and assessing the footage is another great way to find your cause of hip pain during the squat, a butt wink as the cause of posterior pelvis tilt and you may have the issue mentioned in the previous paragraph or you may have tight musculature or connective tissue somewhere in your lower body, the same goes for many issues or imbalances that you may see in your squat such as if you lean more to one side on the descent or ascent of the squat, if one or both knees concave inwards or if your heel lifts up of the ground. 

Stability is another common issue leading to hip pain, the best test for this is to perform a single leg box squat to a parallel position, pay attention as to whether a knee concaves inwards to maintain balance, or if you simply can not maintain balance on one or both legs. Once you have recovered from your injury it is recommended to practice the one legged squat to increase stability while squatting or during sporting movements.

A hip impingement is often caused by the femur coming into contact with the acetabulum excessively, this can cause the femur to move improperly in the hip socket and cause pain and inflammation in the tissues surrounding the joint. As previously mentioned lying down and hugging each knee to your chest and seeing if this brings out pain is one test for hip impingement. Other tests include, lying flat on the ground take one leg and flex your knee to 90 degrees, rotate your leg so that your flexed legs ankle is on top of the others thigh, now allow your knee of the leg of the flexed leg to slowly be lowered to the ground in a relaxed manner, do this on both legs, if you felt pain whilst doing this and/or your knee couldn’t get within 2 fist sizes to the ground on one or both legs you likely are suffering with a hip impingement and poor hip external rotation. 

The next test requires you to lie on your back with your knee on the tested leg facing the ceiling and the knee flexed to 90 degrees, rotate the leg away from the body to assess internal rotation on both legs, if you found restrictions in your hip when doing this in the front of the hip socket this is likely due to the anatomy of your hip socket, however, if you found restrictions elsewhere in the hip you likely have tight muscles surrounding the hip, commonly the piriformis muscle, alternatively if on one side of the body the hip internally rotated excessively you may have the opposite issue of the piriformis being too stretched, often caused by allowing the knee to concave while squatting.

Another test for flexibility requires you to lie on your back on the edge of a flat raised surface, such as a bench or bed, hug your knees than let go of one leg allowing it to drop of the edge of the surface, if the dropped leg was unable to rest on the edge of the surface in a straight line because it rotated in an outwards direction you likely suffer with a tight TFL muscle, if your leg was simply unable to even reach the surface you are likely suffering with a tight rectus femoris muscle.

Sitting on the edge of a bench and raise one of your thighs off the surface and hold it here for about 20 seconds, you can even have a partner push down on your knee for more resistance, try this test on both legs, if this brought about pain you likely have some form of a hip flexor injury. Other tests in a similar vein include tests for adductor injury, lie on your side your top leg should overlap the bottom leg and the bottom of your foot should be firmly placed on the surface, your bottom leg should raise off the group slightly performing the act of hip adduction, hold this position for about 20 seconds or even better get a friend to offer resistance, if this brings about pain you likely have a form of adductor injury. Continuing in this vein, if you have pain in the outside of your hip perform the test of laying on your back with your knee facing the ceiling and your knee flexed to 90 degrees, rotate your foot towards the inside of your body, rotate your leg back to the center position against a partner resisting this motion, you likely have issues relating to the gluteus medius, gluteus minimus or even the TFL muscle. 

A test for hamstring tendinopathy requires you to lay on your back with a raised object such as a bench beneath your feet with one of your feet on the raised object and the other fully extended, perform hip extension to raise your hips of the ground, you can try this again with your knee slightly more extended, this will place more stress on the hamstrings and if it increased pain you are likely suffering with a hamstring tendinopathy.

If you have discovered that you have tight muscles/ connective tissue I recommend performing soft tissue mobilization, a foam roller is a great option, roll back and forth taking time to apply extra pressure around tender spots of the area creating pain for a couple of minutes. The piriformis muscle can be targeted by using a smaller and harder ball, sit on the ball and roll back and forth on the area of the pain, the effected leg should be crossed over the other to better target the piriformis.

Those suffering with a hip impingement should try banded joint mobilization exercises. Those with lateral and posterior impingements should loop a band around their upper thigh pulling their leg laterally, now kneel on the opposing leg, use your hand to help pull your knee across your body and pause here before bringing it back and pausing in the start position, perform this for several repetitions to free up impingements in the hip. Another banded exercise for posterior and lateral hip impingement, requires a lateral pull of a band below the glute while on all four, rock gently backwards and forwards pausing in each position, you can work on your internal rotation by angling your foot out slightly.

If you are suffering with poor internal rotation of the hip a method of helping to deal with this includes setting a bar in a rack at shoulder level, take a big step back and lean over at your torso to grip the bar with both hands at shoulder width, on the target leg lift it off the ground behind you while keeping it straight, turn in the direction of the raised leg exposing your chest outwards, make sure to also point your toes of the target leg outwards, pause here for a bit before bringing your whole body inwards and slightly in the direction of the other foot, pause here and perform about 10 repetitions of this exercise.

For those with a tight piriformis there are several stretches you can regularly perform, first lying down on the floor with your feet planted on the mat, your target foot should be turned inwards and rest on the thigh of the opposing leg, the leg underneath should be pulled upwards with your hands to stretch your piriformis muscle. An alternative stretch is to sit on the edge of a chair and place the foot of the target let on top of the thigh of the other leg, from here lean your chest forward to stretch the piriformis. For a more advanced piriformis stretch, stand fairly far from a raised surface of about knee level, step your target leg up onto the surface by lunging forward, now rotate your knee outwards so that your knee gets as close to the surface as possible, lean forward to stretch the piriformis muscle. Hold these stretched positions for about 3 sets of 30 seconds. After performing these exercises it is important to retest for hip internal rotation to see their effectiveness, and also test during the squat to ensure any issues are improving.

Another good stretch for the hips during late stage rehab of hip pain requires a kettlebell. Hold a kettlebell with both hands in front of your body, drop down onto one knee and the other leg can remain on the foot but angled more outwards, rock back and forth so your knee passes the toes of this leg and then back, make sure to hold each position, this can be a great hip stretch on both sides.

For those suffering with muscle or connective tissue injuries isometric exercises are a great way to speed up the recovery process. Adductor isometric exercises, include laying on your back with your feet planted on the mat, place an object such as a medicine ball between your legs and pinch your knees together, hold this position for about 5 seconds, 20 reps, and 2 sets, progress this exercise lay on your side underneath a bench with one leg on top, pull your hips off the ground by pulling your legs together and raising your hips off the ground, hold this position for about 5 seconds, 10 reps, and 2 sets. Isometric hip flexor exercises include laying on your back with your knees pointing towards the ceiling and a resistance band looped around both feet, extend one of your legs which will pull on the other leg and challenge the hip flexor, hold this position for about 5 seconds, 10 reps, and 2 sets. Finally, gluteus medius isometric exercises include looping a challenging resistance band around both knees, squat down slightly and drive your knees outwards, hold this position for about 5 reps of 10-30 seconds.

From here you can begin to progress into more challenging strength exercises for the hips, in order for all hip musculature to have the strength and coordination to keep not just the hips but the whole body injury free. The bridge and hip thrust is a great exercise to be performed, while loaded or unloaded, in order to activate the glutes especially when pausing at the top position, perform this exercise for about 3 sets of 10 reps. A great exercise for coordination and hip flexor strength includes lying on the floor with your feet up on a bench, and a band looped around your feet, squeeze your glutes to lift your hips off the ground and maintain this position, pull each knee at a time to your chest and then return to the starting position, do this for 2 or 3 sets of 10 reps. Build lateral hip strength by lying on your side with your knees slightly bent and a resistance band around your knees, pop up on your elbow into a side plank and flare your top knee out and pause at the top position, do this for about 2 sets of 10 reps. It is important to note that these exercises should not bring about pain, and if you do experience pain while performing them you may not be ready for the strength phase of hip pain rehab and should take a step back until you are ready.

Along with the strength exercises previously mentioned balance exercises help to build stability to further reduce the risk of future injury, thankfully these exercises are rather simple, all of which should be done barefoot to gain better proprioception. One exercise includes standing steel and leaning your body forward so your chest is parallel with the ground, as you do this extend one of your legs out behind you, and hold this position for about 10 seconds and then return to the start position, perform this exercise for about 1 or 2 sets of 10 reps on alternate legs, you can make this exercise more challenging by turning your chest in and outwards once you have leaned over or even loading this exercise by holding a kettlebell. An exercise for the lateral glutes, is to put a resistance band around both knees and perform squats, another exercise for the lateral glutes requires you to tie a band around the leg just above the knee pulling it inwards and lunge down onto the opposing leg, do both of these exercises for about 2 sets of 20 reps, these are great exercises for not just lateral hip strength but also to coordinate the body to stop the knees from caving in while squatting, or during other sporting movements, which often leads to ACL tears. Many of these exercises can continue in your warm up routine once you have returned to normal lifting.