The Biomechanical Effects That Takes Place With a Weakened Gluteus Muscle

This week's Topic of the Week is written in a more advanced language to encouarge you to stimulate the muscle that is your brain... as well as to encourage you to exercise the muscle that is your glutues medius.  Amazing how one small, weakened muscle can cause so many issues throughout the body... read on to learn more

Posterior (backside)

Anterior (front view)

Anterior (front view)

Optimal joint stability is achieved when the balance between performance and effort is optimized to economize the use of energy.  Instability implicates altered laxity or stiffness values leading to increased joint translations (excessive motion). This results in a new joint position usually with exaggerated or reduced joint compression with a disturbance in performance/effort ratio.

Hip centering moment arms

A weakened gluteus medius muscles, as seen here on the right side of this pictoral diagram, causes unleveling of the pelvis which disrupts  biomechanical forces necessary for proper firing of muscles and stabilization of various joints.

2cm superior (upward) displacement decreases abduction (away from the body) forces 44% and increases the moment arm (work required to perform) 49%. Superior displacement decreased hip flexion force 29% and increases moment arm 22%

Inferior (downward) displacement increases abduction force 20% and moment arm 22%.  Flexion forces increased 4% and the moment arm 12%

Delp et al 1993 Journal of Biomechanics

 

Hip Stabilization

Hip abductors (gluts, tensor fascia latte) play an important role in motion and load transfer through the hip and pelvis. Weakness of the hip abductors decreases proper closing through the sacroiliac joints causing dysfunction to the deep core musculature of the low back (ex: multifidus). Hip abductor weakness also causes changes in movement strategies and leads to compensatory changes in the low back, hip and knee.

SI (sacro-iliac) dysfunction causes delay in activation of the internal oblique muscles, multifidus and gluteus maximus on the side of the dysfunction during stance phase of gait where the foot is touching the ground.

*Pelvic compression belt in scientific studies have caused a significant decrease in quadratus lomborum muscle activity and significant increase in gluteus medius and lumbar multifidus activity.

Lee et al 1997

Eggen et al 2003, Janda 1996

Pool-Goudwaard et al 1998

Cynn et al 2006

Bolgla and Uhl 2005

Hungerford et al 2003

Park et al 2010

Lumbar Spine and Gait

Lumbar fatigue in healthy population causes a decrease in lumbar lordosis (loss of curve) and increase forward trunk lean during running gait. People with low back pain have less control of the lumbopelvic region and are prone to lumbar extensor muscle fatigue which has a significant effect on postural control. Postural stability is compromised as a result of the weakness and this population will be predisposed to further injury or aggravation with a rotational movement or with rotational sports. Participants with history of low back pain experience greater decreased quadriceps activation after lumbar spine extensor fatigue.

Hart et al 2009

Davidson et al 2004

Lin et al 2009

Leetun et al 2004

Scholtes et al 2009

Thoracolumbar Fascia

Multiple muscles attach to the thoracolumbar fascia allowing it to act as a connection point between muscles of the lower back, pelvic and proximal aspect of the lower extremities. This fascia creates stability by producing tension when these muscle contract (hydraulic effect)

Gluteus Medius

What the research and literature are presenting us to date regarding exercise rehab of the gluteus medius

Side lying hip abduction exercises had significantly more EMG activity than clam exercises done at 30 and 60 degrees of hip flexion. It has also been proven in scientific EMG studies to be greater than single legged squat, lateral band walk, single limb deadlift and lunges.

Krause et al 2009

The greatest gluteus medius EMG activity in single leg stance with an abduction and internal rotation force on the pelvis vs. straight abduction force.

Earl et al 2005

In evaluating 5 unilateral weight bearing exercises, wall squat had the most significant EMG activity. In descending order: wall squat, front step up, lateral step up, retro step up, and unilateral mini squat. Overall the greatest glut max EMG activity was during single legged squat and single legged deadlift.

Ayotte et al 2007

No difference in EMG activity of the gluteus medius in single leg squats on stable or unstable surface notes as well.

Lesson from today's Topic of the Week - various low back, hip and pelvic pain and dysfunction often arise from a weakened gluteus medius. This is seen in people who sit for extended periods of time, misalignments of the lower lumbar spine affecting neurological input or those who are left/right leg dominant due to work or sports.  Follow up with your sports medicine doctor if you believe you may be experiencing any of the symptoms listed above.

For a referral to a nationally accredited personal trainer or certified strength and conditioning specialists, contact San Diego Center for Health for a select list of male and female trainer referrals who specialize in exercise rehab, pilates, yoga, TRX and Olympic Weightlifting techniques.