Flexion - Extension

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Flexion the bending of a part, or decreasing the angle between two parts. You flex your hip when you bring your thigh up.
Range of motion: 130° (80-90 for 2-joints).

Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts. You extend your hip when the thigh is moving down or backward.
Range of motion: -10° (10° for 2-joints).

Abduction - Adduction

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Abduction  is the movement that moves the limb away from the midline or median of the body. Hip abduction will result in the knee be lifted up sideways.

Adduction means to move closer to the median plane of the body.  Hip adduction will lower the knee or lift on the opposite side sideways.

Internal - External Rotation

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Internal Rotation is the movement of the hip that rotates it inward.

External Rotation is the movement of the hip that rotates it outward.


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Flexors: Illiopsoas (iliacus and psoas), Rectus Femoris, Sartorius, Pectineus, Tensor Fasciae Latae. 
Extensors: Gluteus Maximus, Semitendinosus, Semimembranosus, Biceps Femoris, Adductor Magnus.
Abductors: Gluteus Medius, Gluteus Minimus, Tensor Fasciae Latae, Sartorius.
Adductors:  Adductor Longus, Adductor Brevis, Adductor Magnus, Pectineus, Gracilis.
Internal rotators: Tensor Fasciae Latae, Gluteus Medius, Gluteus Minimus.
External rotators: Piriformis, Obturator Internus, Obturator Externus, Quadratus Femoris, Gemellus Superior, Gemellus Inferior, Gluteus Maximus, Sartorius. 

Evaluating movement dysfunction

Mobility tests:  Hip
Strength tests:  Hip
Posture Evaluation: Look for bad alignment in all planes. Foot pointing externally might results from weak internal rotators.
FMS: Deep Squat, weakness of the hip abductors or adductors will destabilize the knee.
       Inline Lunge: weakness of the hip abductors or adductors will destabilize the knee.  Lack of strenght will make getting up difficult.
       Active Straight Leg Raise: demonstrate the mobility of the hip extensors.

Flexion - Extension

Running with Low Knee

Most of the time, running low, with a small angle of the knee (should be around 150°) is not cause by a limited range of motion of the knee extension but it can be caused by a weakness of the hip flexors.
Corrective measures:
      Strength:   Straight Leg Raise,     Hip Flexion with Elastic Band

Internal - External Rotation

Running with foot pointing sideways

Foot is pointing sideways because of the hip external rotation.  This, along with a weak foot arch, puts side pressure on the knee reducing the performance and increasing risk of injuries.  Foot and ankle strength should be considered as well.  If mobility and strength of the hip rotators are fine, it is a problem of motor control, the internal rotators not stabilizing the movement.  A rubber band attached to the foot, producing a slight resistance for the hip internal rotators is used while the athlete slowly perform the front part of the running stide (stationary A drill).
Corrective measures:
      Strength:   Leg Internal Rotation,     Leg Internal rotation with Lastic.
      Mobility:   Hip Rotator Stretch