Here are a few of the many interesting points discussed in this article by Dr. Neumann in this 2010 Research Review:
-You must always include both cross-sectional area and moment arm length when assessing force and muscle action.
-The Psoas major acts as an important vertical stabilizer of the lumbar spine, especially in full hip extension, when the greatest passive tension is on the muscle.
-The posterior head of the adductor magnus is a primary extensor
-Co-activating the hip extensors and abdominals while passively stretching the hip flexors can provide an additional stretch on the hip flexors.
-Both the sartorius and long head of the biceps femoris act as secondary external rotators.
-Dynamic stability of the hip during high velocity rotation may be one of the primary functions of the short external rotators.
-The short external rotators provide acetabulofemoral articulation stability (similar to how the infraspinatus and teres minor provide stability at the glenohumeral joint)
-The Gluteus Max. is an important external rotator in closed chain kinematics (such as stopping and cutting).
-At 0 deg. of hip flexion, the Gluteus Max. Anterior fibers act as external rotators, BUT At 45 deg. of hip flexion, the Anterior fibers become internal rotators.
-The piriformis is an external rotator in full extension, but an internal rotator in hip flexion >90 degrees.
- Most adductors become hip extensors between 40 and 70 degrees of hip flexion (the exact degree is not known although research is being done on the topic.)
-The Gluteus Minimus tendon attaches to the Anterior and Superior Joint Capsule of the Hip Joint.
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