Are you practicing Virabhadrasana 2 with your hips "square to the side" and your front hip bone lifted in an effort to "make your pelvis more level"? These two cues seem to be very popular in Warrior 2, and while they might have some benefit early on, as your flexibility increases there is a good chance that they will lead to bony compression in your hip joints, which over time might wear down the cartilage and other soft tissues in and around the hip. This isn't going to benefit you in any way, and could potentially lead to osteoarthritis later in life, so it's good to learn how to recognize compression when it's happening so that you can back off. And if you're teaching asana, it's good to know how to cue the posture to help your students avoid compression.
Benefits of Virabhadrasana 2
Warrior 2 strengthens and/or builds endurance in the outer hips (gluteus medius and some of the lateral rotators), anterior thighs (the vasti group of the quadriceps) and outer shoulders (lateral deltoids), and stretches muscles along the inner thighs (most of the adductors). Because a fair amount of lateral rotation is required in the front hip, it also stretches the piriformis (read about how the piriformis becomes a medial rotator if the thigh is flexed sufficiently), which will begin to make Sukhasana (comfortable pose), Agnisambhasana (fire-log pose), and other postures requiring lateral rotation more accessible. On a psychoenergetic level, many report that Warrior 2 helps them feel more grounded and confident, which relates to fortifying the muladhara chakra at the base of the spine. It also challenges one's will power to stay in the posture, so it seems that Warrior 2 would have a beneficial effect on the manipura chakra (the 3rd chakra, located at the solar plexus).
Is It Hip to Be Square?
Encouraging the pelvis to turn toward the side while stabilizing the front knee over the heel will increase the stretch on the adductors of the front thigh as well as on the piriformis. However, it we are flexible enough to turn the pelvis completely to the side then there is a good chance that we might create some compression in the outer front hip joint between the greater trochanter of the femur and the posterior aspect of the hip bone at the acetabulum (see illustration, below):
What Would Compression in the Front Hip Feel Like?
If you are squaring your hips to the side in Warrior 2 but aren't feeling any stretch in your inner thigh, it might just feel like you can't turn your pelvis further, but you won't have any kind of pain in your outer hip. However, if you keep doing it you might eventually break through some of the soft tissue on the outer hip (muscle tendons, ligaments, cartilage) and get to a place where the periostia of the hip and femur bones is compressing, which will likely create some acute pain at the area of compression. Ideally, you would stop compressing long before this ever happens... because by the time you're feeling pain some damage has already occurred.
Alternative Verbal Cues
Instead of giving the cue to "square the pelvis to the side," which as mentioned above might eventually lead to compression in the outer front hip, one strategy is to just not cue the pelvis at all! You could cue your students to line the front knee up over the front heel, and to stabilize the knee as your slowly turn the torso toward the side wall, allowing the pelvis to accommodate. By cuing the torso to rotate toward the side, you'll engage and strengthen your internal and external abdominal obliques. The pelvis will follow the torso toward the side somewhat, but you won't be forcing it toward the side muscularly. Note that you'll still need to engage your outer front hip abductors/lateral rotators to stabilize your knee over your heel, because when the torso turns toward the side the pelvis will follow and potentially try to pull the knee along as well. Here's an image showing the torso toward side, with the pelvis not square (notice the increased space between the greater trochanter and posterior hip):
What About Making the Pelvis Level?
Another common alignment cue in Warrior 2 is to "lift the front hip to make it level with the back hip." Doing so would increase the stretch along the inner thigh of the back leg and allow the spine to be more vertical without any lumbar curvature in the frontal plane. However, trying the make the pelvis level when the back thigh is so abducted can create compression between the greater trochanter of the back thigh and the superior aspect of the hip socket (acetabulum):
Please Note: while the bony pelvis in the image above is level and in the image below is not level, the model in both pics is the same (and his pelvis is not level).
By letting the pelvis tip forward a little bit, you create more clearance between these structures and can avoid compression:
The benefits of lifting the front hip bone up to make the pelvis more level are that you'll increase the stretch on the adductors of the back thigh. However, as illustrated above if you lift the front hip bone too much you might create compression in the outside of the back hip. To encourage more space in the back hip, you might say something like, "Place your hands on your hip bones to get a sense of how high your front hip is compared to your back hip; if you feel that your front hip is a lot lower than your back hip, lift it up a little so that it's almost as high as your back hip; as you do, pay attention to your outer back hip - if you feel a hard stop there, or a little pain, then lower the front hip a little more." You could also walk around the room and work with students individually to find the right amount of tilt.
If the front hip is a little lower than the back hip and the torso is kept completely vertical, then the lumbar spine will have to compensate by lateral flexing toward the front leg. This isn't necessarily bad, provided that it's not extreme and that you do the posture the same way on both sides. However, you could also avoid the lateral flexion of the lumbar spine by leaning the whole torso toward the front leg a little bit, so that the trunk and pelvis are more aligned. Practicing the posture this way would also load the front hip more, creating more work for the hip extensors and quadriceps. In some circles this variation of Warrior 2 is called Future Warrior, because it's like a Warrior 2 leaning "into the future."
Here's a short video where I explain most of the above in about 4 minutes ;-)
Time to Play
If you've been reading along and have made it this far, you must be itching to get on your mat and explore some of this. When you do, I recommend that you attempt to square your pelvis to the side to see if you can feel compression on the outside of your front hip, and to "make the pelvis" level to see if you feel compression on the outside of your back hip. If you do, try working with the above cues to create more space in your hips. If you don't, there are a few things to consider:
As usual, questions and comments are welcome and appreciated. And if you found this content valuable please share with friends!