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Triathlon Success: Hip Flexor Function

Two of the most important muscles for efficient running and a pain free set of knees are not visible in the mirror.  Most people have never heard the names of these muscles.  Located deep inside the body, covered by innards and all too often, layers of mesenteric fat, these muscles labor unloved and forgotten.  Triathletes interested in optimal performance and a body that remains injury free should give some attention to the iliacus and psoas muscles.

Anatomy

Five muscles flex the hip–bring your femur forward.  Three of the hip flexors attach to the front of your pelvis and run down the front and sides of your thigh.  They are the sartorius, tensor fascia latae, and the rectus femoris.  Two of the muscles attach to your spine and posterior pelvis and travel across all of the lumbar vertebrae, the sacroiliac joint, and the front of the hip joint.  They are the iliacus and psoas muscles.  The sartorius, tensor fascia latae, and the rectus femoris can lift your femur to parallel, 90 degrees hip flexion, and no further.  The iliacus and psoas are responsible for lifting the hip above parallel.  Many people have very weak iliacus and psoas muscles and are unable to flex the hip above 90 degrees.

Multi Joint Control

“Hip flexor” is a very simplistic description of the function of the iliacus and psoas muscles.  The iliacus and psoas flex the hip, but they also rotate the hip, stabilize the pelvic girdle / lumbar spine, decelerate hip extension and co-contract with a team of muscles to hold us upright.  Properly functioning iliacus and psoas muscles keep the pelvis stable when you walk or run and this mitigates stress on the knees and lower back.  When the iliacus and psoas muscles are weak, the pelvis tilts forward and backward.  This rotates the femur in and out and twists the knee.  Your knee joint likes to bend back and forth and dislikes any extra rotation.  Extra knee rotation wears out the back of the kneecap (patella) and places stress on the supportive cartilage (medial and lateral meniscus) of the knee.  A triathlete with a wobbly pelvis places significantly more stress on their lumbar spine.

Triathalon Considerations

Riding a bike shortens and neurologically anesthetizes the iliacus and psoas muscles.  A tight psoas muscle compresses the lumbar vertebrae together and increases pressure in the lumbar discs.  Athletes with “quad strains” often have pain in the sartorius and rectus femoris muscles that has been brought on by overuse of these muscle as they compensate for a weak iliacus and psoas muscles.  Tight and inhibited iliacus and psoas muscles are responsible for the wobbly gait pattern you frequently see as the triathlete transitions from the bike to the run.  Two drills that will improve the function of the iliacus and psoas muscles are listed below.  Read the directions and watch the video.

Standing Hip Flexor Isometric

The Standing Hip Flexor Isometric drill functions as both an evaluation and a method of restoring iliacus and psoas function.  If you struggle with this exercise, you need to spend some time and effort on improving the performance of your iliacus and psoas.  Listed below is a description of the exercise and several activity regressions and progressions.

You need a box or exercise bench.  The taller you are, the higher the bench.  Six feet tall, try a bench that is 24 inches high.  Five foot, four inches, try a twelve inch box.  A mirror for visual feedback is helpful.  Stand with the right foot on the bench and the left foot on the floor.  Hold a pvc pipe, broomstick, or golf club overhead.  Brace the abdominal muscles to keep a tall spinal position and tight lordosis (inward curve) in your lower back.  Lift the right foot off the bench by pulling the thigh up with the muscles in front of the hip.  Hold the foot off the bench in a solid and stable position for five seconds and then lower.  Do not let the position of the spine change.  Do not bend the left knee or tilt the pelvis.  The only joint that moves is the right hip.  Athletes should be able to lift and hold the right knee 30 degrees above waist level.  Start with sets of three repetitions and alternate sides.  As you get stronger, increase the duration that you hold the foot up to ten  seconds.  If one side is weaker than the other, perform more repetitions or an extra set on that side.

Bench Assisted Hip Flexor Stretch

This drill will improve hip extension range of motion and enhance mobility in all of the hip flexor muscles.  Bicyclists often have very flexed lumbar spines and limited lumbar and/or hip extension.  This mobility exercise is the antidote for the physical restrictions created by too much time in the saddle.

You will need an exercise bench or a padded chair that is 12 to 16 inches tall.  Place a cushion or Airex pad directly in front of the bench.  Set up with the left foot on the floor in front of the Airex pad and aligned with the left hip.  Place the right knee on the Airex pad and the front of the right foot up on the bench.  Stay tall through the spine and hold the position for twenty to thirty seconds.  For many people this will be enough stretch.  If you are able take the arms overhead.  Work further into the movement by bending the front knee and moving forward.  Repeat on the other side.

Video of these exercises can be found here: View Video

 Michael S. O’Hara, PT, OCS, CSCS

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