Hi Kontoryoga. Thanks for reaching out.
I would never specify “How much external rotation” at the hip socket that a student needs in a pose because the answer is always, “it depends!” The bony limits to external rotation vary dramatically from one student to another, and this is due to the unique shape and orientation of the hip socket as well as the length, width of the neck of the femur and its angle to the shaft. Some people have very limited range of motion for external rotation (or any other movements) and others have lots of room to move. This ignores the tensile resistances that also limit movements.
In the poses you mention, the hips are moving into extension. The angle/orientation of the hip socket can make this easier for some; harder for others. But also the diagonal angle of the fibers of the capsular ligaments that wrap the femur head into the hip socket makes it easier for us to flex the hips and harder to extend them. I describe this in lots of detail in my book [url=
https://yinyoga.com/ybyy/]
Your Body, Your Yoga[/url}. Here is a snippet of that:
THE HIP-JOINT CAPSULE AND LIGAMENTS
The femur is bound to the pelvis by five capsular ligaments surrounding and inside the synovial joint capsule of the hip joint. The names of these ligaments come from the bones to which they attach:
- the iliofemoral ligament (which joins the femur to the ilium), one of the thickest and strongest ligaments in our body;
the ischiofemoral ligament (which joins the femur to the ischium);
the pubofemoral ligament (which joins the femur to the pubis);
the ligamentum of the femur’s head, also called the ligamentum teres (which joins the femur to the acetabulum);
the transverse ligament of the acetabulum, which creates a bottom shelf reinforcing the inferior rim of the la- brum (not shown in the diagrams, but it is the inferior portion of the joint capsule)
The arrangement of the fibers of the first three ligaments are key in restricting movements (see figure 2.23). They are jointly called the capsular ligaments and reinforce the joint capsule in a variety of directions:
- the iliofemoral ligament is the strongest of the three. It reinforces the anterior and superior portions of the joint capsule and can limit external rotation and ex- tension. We will often consider it as two ligaments, because the different fibers (superior and anterior) can respond differently to stress;
the pubofemoral ligament reinforces the anterior and inferior part of the capsule, limiting abduction and ex- tension;
the ischiofemoral ligament reinforces the posteri- or capsule, can limit extension and internal rotation, and—if the hip is flexed—can also limit adduction.
Not surprisingly, not all experts agree upon the individual functions of these ligaments! Some researchers feel that external rotation is not limited by the ligaments at all, while internal rotation is most strongly limited. The role of the ligamentum teres is still being debated; it can contribute a minimal amount of resistance to the movements of adduction, flexion and external rotation, but its main function seems to be as an anchor for the femur into the center of the acetabulum—and, in youth, as a pathway for blood vessels to the head of the femur.
The capsular ligament fibers are oriented diagonally around the joint capsule so that they loosen when the hip is flexed but be- come taut when the hip is extended to its maximum. Indeed, the passive tension of these three ligaments is the reason extension is so limited. When the hip is fully extended, slightly internal- ly rotated and abducted, it is in its close-packed position, which means the joint has its largest degree of stability. These three ligaments effectively “screw down” the femur into the socket at full extension, and there is no “play” or wiggle-room in the joint: it is firmly held (see figure 2.45). Figure 2.46 shows how the capsular ligaments tighten or relax in various movements
TABLE 2.6 Tension from ligaments limits movement in the hip socket in a variety of directions.
- HIP MOVEMENT — RESISTING LIGAMENTS
Flexion — Inferior joint capsule, >90°, inferior fibers of the ischiofemoral ligament; >120°, the ischiofemoral ligament; >160°, all three ligaments
Extension — Iliofemoral ligament; Pubofemoral ligament; Ischiofemoral ligament; Anterior joint capsule
Abduction — Pubofemoral ligament; Anterior iliofemoral; Inferior joint capsule
Adduction — Iliofemoral ligament; Iliotibial band
External (lateral) rotation — Anterior iliofemoral ligament; Pubofemoral ligament; Iliotibial band
Internal (medial) rotation — Ischiofemoral ligament; Posterior joint capsule
From the above, you may see that in order to extend the hips maximally, it is necessary to allow external rotation at the hip socket and some abduction. The only reason I would ever encourage a student to reduce their external rotation is if they wanted to work on strengthening their adductor muscles, but I would warn them that doing so would probably reduce the amount of extension they could generate in their hips. Conversely, if you want a student to strength their gluteal muscles, well, these are external rotators so their feet will point out even more. What is your intention?
I hope this helps
Cheers
Bernie
