The common practice of stretching “tight” hip flexors may not always be correct and reliable, particularly for those grappling with pain at the anterior (front of) the hip. While hip flexor conditioning often takes a back seat in exercise regimens for such discomfort, this idea raises important considerations that challenge conventional wisdom.
The iliopsoas musculotendinous unit is the major hip flexor. Iliopsoas-related groin pain is situated towards the front, over the iliopsoas muscle, positioned laterally (to the outside of) the adductors (groin muscles), and spanning across the hip joint in the mid-inguinal region.
The pain might extend into the lower abdomen and a short distance down the proximal thigh, presenting as a deep discomfort or tightness. This discomfort is often described during activities involving the hip flexor complex, either when loaded into flexion (knee to chest) or stretched into extension (thigh behind body).
In runners experiencing iliopsoas-related pain, the issue is typically noticeable in the late stance and early swing phases of running. Runners may report that the hip tightens anteriorly during their run, causing pain and possibly limiting stride length.
Symptoms tend to intensify with increased running distance and speed, especially with longer strides. Walkers may also experience this pain, particularly in late stance and early swing phases, and at higher speeds and longer stride lengths.
The onset of iliopsoas-related groin pain can be either acute, often associated with activities like kicking, sprinting, tackling, and sliding, or more gradual, possibly linked to changes in activity or previous surgeries.
People with iliopsoas-related groin pain may also report a snapping sensation at the anterior hip, often accompanied by an audible click. This snapping typically occurs during eccentric lowering of a flexed hip, especially if externally rotated.
The first crucial question to pose when considering whether or not to stretch the hip flexors as a form of treatment is whether the person genuinely exhibits restricted hip extension range DUE TO tight hip flexors. Could this instead be a bony block at the hip joint (‘ball and socket’), cartilage pathology, reduced movement due to the pelvic angle, or simply avoidance of this movement due to pain?
There does remain a school of thought that suggests that muscles and joints behave differently in the presence of pain, and that perhaps muscles that feel ‘tight’ are perhaps simply more symptomatic / fatigued. In my professional career to date, I have often noticed this trend. A client will present to me with “tight hamstrings,” for example, only for me to find that their hamstring flexibility is excellent.
Like a lot of heuristics (patterns of thinking) in physio and rehab, some assumptions should be avoided. To objectively measure hip extension, physio’s often use the ‘modified Thomas test.’ However, standardising and interpreting results become pivotal challenges with this test. Clinicians need to ponder aspects like pelvic position, defining ‘normal’ ranges, and ensuring reproducibility for effective assessment.
Moving beyond mere measurement, the efficacy of hip flexor stretching should rightly be questioned. There is a scarcity of high-quality evidence supporting the positive impact of passive stretching on anterior hip pain. Moreover, the potential long-term benefits of such stretching on hip extension range remain uncertain, with only short-term increases documented in pain-free populations. This is not to say that stretching is a no go zone full stop. Personally, I still believe it has its place, only in the right circumstances.
‘Iliopsoas (hip flexor) impingement’ is a phenomenon associating the hip flexor tendon with anterior labral (cartilage) pathology. There is a crucial gap in research clarity regarding the prolonged effects of excessive loads (i.e. stretching) on these structures. Thus, the risk of exacerbating pain in those already dealing with anterior pathologies is worth acknowledging, again cautioning against indiscriminate application of hip flexor stretching. Apart from which, the mechanism of how increasing muscle length would ease impingement is yet to be addressed.
Again, this is not to say that stretching should never be used. Or, that it is always unhelpful to stretch the hip flexors, or muscles in general for that matter. As always, rehabilitation should remain informed, individualised and monitored.
Clients have a right to ask questions to understand why a treatment is being prescribed. However, perpetuating certain dogmas such as blaming muscle groups for a person’s pain, without thorough history taking, biomechanical, and joint assessment, should be avoided.
Evan Armstrong, Physiotherapist & Managing Director, Destiny Health.
References
Beneck, G., Selkowitz, D., Janzen, D., Malecha, E. and Tiemeyer, B., 2018. The influence of pelvic rotation on clinical measurements of hip flexion and extension range of motion across sex and age. Physical Therapy in Sport, 30, pp.1-7.
Domb, B., Shindle, M., McArthur, B., Voos, J., Magennis, E. and Kelly, B., 2011. Iliopsoas Impingement: A Newly Identified Cause of Labral Pathology in the Hip. HSS Journal ®, 7(2), pp.145-150.
Mettler, J., Shapiro, R. and Pohl, M., 2019. Effects of a Hip Flexor Stretching Program on Running Kinematics in Individuals With Limited Passive Hip Extension. Journal of Strength and Conditioning Research, 33(12), pp.3338-3344.
Watt, J., Jackson, K., Franz, J., Dicharry, J., Evans, J. and Kerrigan, D., 2011. Effect of a Supervised Hip Flexor Stretching Program on Gait in Elderly Individuals. PM&R, 3(4), pp.324-329.
Yoshio, M., Murakami, G., Sato, T., Sato, S. and Noriyasu, S., 2002. The function of the psoas major muscle: passive kinetics and morphological studies using donated cadavers. Journal of Orthopaedic Science, 7(2), pp.199-207.