The Hip Flexors

The Anterior Stabilizers of the Hipthe hip flexorspsoas majorhis is the second in a series of articles that identify and define the function
of the muscles that support the major joints in the body. These articles address how muscles work synergistically to create efficient movement at each joint. This article addresses the flexor muscles of the hip.

1. The tensor fascia latae (TFL) lies on the outer, anterior surface of the iliac crest. Proximally, it lies between the gluteus medius and the sartorius. It inserts into the ilio tibial (IT) band, which is a strong sheet of fascia that runs along the lateral aspect of the thigh, which then inserts into the tibial tubercle.

2. The psoas major and iliacus share a common tendon, which attaches at the lesser trochanter (iliopsoas). The psoas major lies along the anterior portion of the lumbar spine and coinciding intervertebral discs from T12 down to L5. The muscle cascades down towards the hip joint, where at the ilium, it joins the iliacus muscle to form the iliopsoas. The iliacus originates from the iliac fossa as it blends with the psoas.

3. The rectus femoris attaches to the pelvis in two positions—at the anterior superior iliac spine and at another tendon that attaches at the posterior brim of the acetabulum. The muscle attaches distally through the patella tendon into the tibial tuberosity.

The primary function of the TFL is
hip flexion. As noted, the TFL works with other main hip flexors, which include the rectus femoris, psoas and iliacus. Other muscles work as synergists in these muscles’ roles in hip flexion. These muscles include: the pectineus, the anterior gluteus medius and minimus, and the sartorius.

For efficient motion in hip flexion,
all of these muscles must work together or the plane of motion will be altered. Since many of these muscles attain a component of rotation as each attempts to flex the hip, any weakness will cause a deviation specific toward the plane of the dominant muscle.

Thus, it is important to recognize that, when designing exercise programs, the dominant muscles must not be allowed to compensate for the weak muscles. If muscular imbalances are not addressed, they will be reinforced with exercise.

As noted in the last issue, the primary philosophy behind muscle activation techniques is that muscle tightness is secondary to muscle weakness. Addressing muscle weaknesses prevents the muscles that are being stretched from continually tightening back up. ‘

Range of motion limitations are typically a result of muscle weaknesses; therefore, the range of motion exam (see sidebar) indicates isolated muscle weaknesses.

When muscle weaknesses are identified, a trainer can much more efficiently design exercise programs. l

Tiliacustensor fascia lataerectus femoris

Origin: Insertion: Primary Action: Closed-Chain Action:
Tensor Fascia anterior part of the iliotibial band flexes the hip with stabilizes knee in
outer lip of the ilium, abduction and frontal plane (acts
posterior to the anterior internal rotation as an active lateral
superior iliac spine collateral ligament)

Psoas Major bodies of transverse lesser trochanter flexes the hip with eccentrically controls
processes of lumbar of the femur external rotation and movements of
vertebrae and 12th slight abduction; with backward bending
thoracic vertebrae femur stabilized, in- and posterior tilt
creases lumbar lordosis
and anterior pelvic tilt

Iliacus iliac fossa lesser trochanter flexes the hip with eccentrically controls
of the femur external rotation and movements of
slight abduction backward bending
and posterior tilt

Rectus Femoris anterior inferior tibial tuberosity flexes the hip and eccentrically controls
iliac spine extends the knee knee flexion

IDEA PERSONAL Trainer april 2002 fine anatomy

When recommending strengthening exercises for the hip flexor muscles, remember that they act in both the open and closed chains. Each muscle will have specific exercises for each isolated (open-chain) function and closed-chain (weight-bearing) exercises, which involve the hip flexors’ role in regulating hip extension. An isolated closed-chain exercise also is recommended for reinforcing the strength of the TFL in its role of stabilizing the hip and of
the rectus femoris in its role of eccentrically controlling knee flexion.

Since the TFL acts as a lateral stabilizer with the gluteus medius and minimus in the closed chain and the rectus femoris controls knee flexion, these muscles must possess adequate, isolated strength in order to resist the forces transmitted to the hip and knee through gravity and ground reaction forces. Like all muscles of the hip, significant strength is necessary for normal functional movements. The ideal program design would begin with isolated strengthening exercises for two to three weeks, followed by weight-bearing exercises for lateral stability.

Note: The following exercises are designed to improve proprioception. The primary goal is to increase the ability of the muscle to contract through its full range of motion (ROM). Therefore, with the open-chain exercises, work the muscles into the shortened range and emphasize the components of rotation.

In order to improve neurological input, the following exercises must be performed with an emphasis on control and at high repetitions for neurological reinforcement. Have the client perform three sets of 20 repetitions of each exercise, with rest intervals no longer than one minute.

Isolated Strengthening Exercises

1. Seated Hip Flexion: This is a great exercise for a client who demonstrates significant overall weakness in the hip flexors. The primary goal is to improve general strength in hip flexion.

Performance

Compensations

2. Hip Flexion With Tension Band
or Cable: This open-chain exercise isolates the specific muscles related to hip flexion. It also strengthens the hip flexors on the non-weight-bearing leg. Emphasize eccentric control with each repetition. The joint position and joint angle will vary slightly in order to emphasize each of the hip flexor muscles.

A. Performance: tensor fascia latae

Compensations

B. Performance: psoas major

Compensations

C. Performance: iliacus

Compensations

D. Performance: rectus femoris

Compensations

3. Stool Squats: This is the first closed-chain exercise; it strengthens the rectus femoris in its role of eccentrically preventing knee flexion.

Note that the weight-bearing leg is the leg being strengthened.

Performance

Compensations

4. Posterior Pull With Tension Band: This closed-chain exercise strengthens the hip flexors in their role of hip stabilization.

Performance

Compensations

2b IDEA PERSONAL Trainer april 2002

2bIDEA PERSONAL Trainer april 2002 fine anatomy

The following tests identify muscle weaknesses in the hip flexor muscles. In each test, the client will lie supine and the trainer will look for asymmetrical motion between the two legs.

1. Perform with straight leg, hip flexion (30 degrees), checking active ROM for internal rotation of the femur.

Limitation in motion represents weakness of the rectus femoris.

2. Perform with straight leg, hip flexion (30 degrees), checking active ROM for external rotation of the femur.

Limitation in motion represents weakness of the iliacus.

3. Perform with straight leg, hip
flexion (30 degrees), then abduct
(30 degrees); check active ROM
for internal rotation of the femur.

Limitation in motion represents weakness of the tensor fascia latae (TFL).

4. Perform with straight leg, hip
flexion (30 degrees), abduction
(20 degrees), checking ROM for external rotation of the femur.

Limitation in motion represents weakness of the psoas major.

IDEA PERSONAL Trainer april 2002