The Importance of Hip Flexion Strength

Today’s post is a guest article written by Chris Johnson on the the importance of hip flexion strength when dealing with lower extremity pathology.

 

The Importance of Seated Hip Flexion Strength

Just over eight years ago, I accepted my first job as a physical therapist at the Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT) of Lenox Hill Hospital. This experience afforded me the opportunity to train under the late Dr. James A Nicholas, one of the “Founding Fathers” of sports medicine, and the winner of the 2004 President’s Cup award from the Sports Section of the American Physical Therapy Association (APTA). One of the greatest lessons I learned from Dr. Nicholas pertained to “linkage” and the importance of assessing seated hip flexion strength in patients presenting with lower extremity pathology, especially patellofemoral pain syndrome (PFPS).

In 1976, Dr. Nicholas and colleagues published an article in The American Journal of Sports Medicine entitled, “A study of thigh muscle weakness in different pathological states of the lower extremity.” This study documented that subjects with patellofemoral problems exhibited significant hip flexor weakness on the involved side when compared to a group of controls. Furthermore, Dr. Nicholas and his co-authors concluded that the hip flexor resistance test affords a quick and accurate way of detecting unilateral weakness of the trunk, thigh flexors, and quadriceps group making it a valuable clinical assessment tool.

More recently (2006), Tim Tyler and colleagues did a study investigating the role of hip muscle function in the treatment of PFPS. This study corroborated Dr. Nicholas’s original findings and demonstrated the importance of addressing hip flexor strength in the context of PFPS. The authors proposed that improving hip flexor strength helps to establish a stable pelvis during gait thus preventing it from going into excessive anterior tilt, which would result in excessive femoral internal rotation. The iliopsoas is also a secondary femoral external rotator and strengthening this muscle helps to align the trochlear groove and patella. It should also be mentioned that this study documented the importance of establishing adequate flexibility of the hip flexors and iliotibial band (ITB), which would induce posterior pelvic tilt and relative femoral external rotation. One of the major takeaways from this article is that in addition to resolving any hip flexor tightness, it is also important to ensure adequate strength of this muscle group.

 

Assessing Hip Flexion Strength

While clinicians and fitness professionals routinely assess for and correct hip flexor tightness, it has been my experience that screening for hip flexor weakness in a seated position is not routinely performed. Considering the research, medical and allied health professionals should include this as part of their screening or examination process, especially in the context of lower extremity pathology such as PFPS. To perform this test, the patient should be seated at the edge of a table or plinth with their back straight and legs dangling over the edge of the table while holding on to the front of the table. The patient is then instructed to flex one hip by bringing the knee up towards the chest and to hold it in place while the examiner pushes down on the thigh with the palm of his or her hand. Comparison is then made to the contralateral side. It is the author’s opinions that break testing is the best approach to strength test the hip flexors given the limited range available in a seated position. Standard manual muscle testing grades can be applied or clinicians can use a handheld dynamometer/manual muscle tester to establish a more specific strength index.

When assessing seated hip flexion strength, there are several key to ensure the test is properly performed. First off, patients should have 120 degrees of clean hip flexion so that they can get the involved extremity in to the proper test position without any compensatory motion. Secondly, patients should hold on the front of the plinth to prevent leaning back, which is a common substitution or trick movement when testing hip flexor strength. This will allow the examiner to isolate the hip flexor muscle group as well, thereby ensuring accurate results. Lastly, pay close attention to the low back during testing as patients presenting with hip flexor weakness often fall into excessive anterior pelvic tilt secondary to poor spinal stability, which can result in shearing of the lumbar segments. This may also indicate the need to incorporate spinal stabilization exercises in to the overall treatment program.  Here is a quick video demonstration:

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Next time you find yourself evaluating or treating a patient suffering from a lower extremity injury, make sure to test their seated hip flexion strength, especially in the context of PFPS.  And remember that it is not only important for the hip flexors to be extensible but also for them to be STRONG, and without assign hip flexion strength you’ll never know!

 

References:

  1. Nicholas JA, Strizak AM, Veras G. A study of thigh muscle weakness in different pathological states of the lower extremity. Am J Sports Med. 1976 Nov-Dec:4: 241-8.
  2. Tyler TF, Nicholas SJ, Mullaney MJ, McHugh MP. The role of hip muscle function in the treatment of patellofemoral pain syndrome. Am J Sports Med. 2006 Apr; 34(4): 630-6.

 

About the Author

Chris Johnson, MPT, MCMT, ITCA is a physical therapist and competititive triathlete.  He has a private physical therapy practice in Manhattan.  Youcan learn more from Chris at his website ChrisJohnsonPT.com and Twitter.

Chris has a great website that has a lot of information, especially in regard to running and triathlons.  Thanks for such a great article on the importance of hip flexion strength!

 

 

 

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10 Responses to “The Importance of Hip Flexion Strength”

  1. Hello Chris,

    thanks for writing down and sharing your thoughts!
    The passed tight hip flexors decade is followed by a time of over stretching & under strengthening of the region.

    Most of the rehabilitants i see (up to major league in Handball, Golf, Icehockey and Football) are lacking the ability reach the testing position of 120° Hip F.
    If the get the knee hight enough, the Lx breaks out.
    After detecting this weakness we “train the test” in different positions, starting with the stabilizer and progress them into some bent and straight leg get ups.

    There are a few questions which I’m currently thinking about
    Has someone looked for or proposed how strong they have to be (pull – push ratio)?
    Is more strength in the seated hip flexor test linked to an increase in dynamic control?
    What is the progression of the seated hip flexor test?

    Would be nice to hear your thoughts on this!

    With regards from sunny Bavaria

    Steffen

  2. Hello Chris

    Thanks for a good post and paying attention to the lack of hip flexor strength to PFPS. I just wanted to know if you had seen some research about some norms in strength of iliopsoas if tested with hand held dynamometer (Lafayette). Endurance can be tested with holding time capacity but when is the strength insufficent ?

  3. Interesting post. I am usually more concerned with hip extension and abduction strength. Does a tight iliopsoas complex create a posterior tilt? I always thought it pulled you into an anterior tilt – this would lengthen and inhibit the hip extensors (ie. lower crossed symdrome).

  4. Stefan,
    There is some normative data that Dr. Nicholas collected over nearly a decade of testing though it never reach publication as he was starting to get a bit older and got lost in the mix. I can get access to those normative values and will follow up with you once I get a hold of them. It’s scary how strong people should be

    Steffen,
    Great comment about the fact that most patients dont have adequate hip flexio to even get in to the test position. I could not agree with you more which is probably why testing seated hip flexion strength is not routinely performed. I usually dont assess it until Ive cleaned up hip flexion so the patient can reach 120 degrees. In terms of dynamic control, there is no great research that I am aware of though given the secondary role of the iliopsoas as a hip external rotator, having adequate strength would seem important to help align the patella in the trochlear groove by way of femoral external rotation. I think it’s oftentimes an overlooked piece of the puzzle and is overshadowed by the hip abductors and external rotators.

    Brendan,
    I agree with you in terms of the importance of hip abduction and extension strength but also important to ensure adequate abductor and external rotatoin strength. And most importantly ensure that they have a stable base to work off by ensuring rock solid lumbopelvic stability. Hip flexor tightness will create an anterior tilt of the pelvis so you are correct in that statement though it’s not always enough just to stretch the hip flexors but also to ensure that they have adequate strength. I am downright scared by just how weak many patients are in terms of their hip flexion strength. Muscles need to be more than just extensible.

    Thanks everyone for your interest in this post and for Mike affording me the opportunity to share some content. Hope everyone is kicking butt and helping people do the things they love in life

  5. Hi Chris,

    Very nice post. Any thoughts/opinions as to how patients with PFPS develop weak hip flexors? In other words, do you feel that their hip flexors gradually weaken as a result of the pain associated with the knee pathology (tendency to avoid bearing full weight through that extremity, often leading to hesitation and less power produced during swing phase) or that the hip flexor weakness is one of the underlying causes? Or, perhaps a bit of both….both factors fueling one other until the patient has a full-blown case of PFPS. I know, a sort of chicken-egg question. I’d be interested to hear what you’ve seen throughout your clinical experience.

    Although I do acknowledge the importance of Janda’s work regarding lower crossed syndrome, I believe some clinicians have taken this concept to the extreme by ignoring hip flexor strengthening in a functional position in favor of more glute activation work. The individual characteristics of some patients do not fit cleanly into the lower crossed syndrome model, and these patients require a slightly different approach. I appreciate your post shedding light on this important topic.

  6. Hi Chris,
    Really interesting post, I must admit in dealing with my own PFPS I have been guilty of focusing primarily on hip extension strength and hip flexion mobility (or decreased tension). But given the function and attachments of ilio psoas it makes sense that you need good strength and mobility to provide good lumbo-pelvic stability. I guess a take home message is that you can be strong without being “tight”.

  7. I would love to see an article based on the data you reference: “I can get access to those normative values and will follow up with you once I get a hold of them. It’s scary how strong people should be”

    It’s amazing how neglected the hip flexors are in everyday life, but even to a minor extent in medical practice like you mentioned.

    Do you think you could expand on this point:”The authors proposed that improving hip flexor strength helps to establish a stable pelvis during gait thus preventing it from going into excessive anterior tilt, which would result in excessive femoral internal rotation.”

    Did they ever quantify any final results?

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