Unlocking Hip Flexor Pain: How to Diagnose and Recover from Strain or Tendonitis
My favorite pun regarding this muscle group as a mildly humerus (<---haha!) physical therapist is to start any conversation about the hip flexors saying:
“Psoas you know….”
Life would be so hard if you couldn’t make yourself laugh, am I right? I am lucky enough to have the talent of making others laugh, too, even if my jokes are a bit of a “stretch.”
Okay, I will stop. For now anyway.
Psoas I was saying (I can’t help myself), the hip flexor muscle group consists of about 11 muscles; however, the primary hip flexors include the Psoas Major and the Iliacus. These two muscles join together in the pelvis near the inguinal ligament and cross the hip joint to attach at the thigh bone (femur). Therefore, these muscles are often named together as the “Iliopsoas.”
Other muscles that perform hip flexion include:
Tensor Fascia Lata (TFL)
Sartorius
Rectus Femoris
Adductor Longus
Adductor Magnus
Adductor Brevis
Pectineus
Let’s be clear that a strain and tendonitis are different injuries. A strain is defined as an overstretched or torn muscle and/or tendon whereas tendonitis is the inflammation or irritation of the tendon. We use the word tendinosis to describe the chronic degeneration of the collagen fibers within the tendon. The commonality of these injuries is their tendon-cy (pun of course intended) to occur with overuse and repetitive irritation. What makes them different? Well, a strain typically occurs when a muscle is overstretched and load is applied to it. Who the hell has “overstretched” hip flexors at baseline? Well if you are a runner and you are reading this book, it is probably not you. Your hip flexors are more likely tight and susceptible to tendonitis from overuse and poor repetitive motion. After all, running is essentially a series of one legged squats and a crap ton of hip flexion.
How Does A Hip Flexor Strain Happen?
We will discuss how a strain occurs first as this is short and sweet. Well, not sweet, but definitely short. Well not short, because the muscle is longer when it happens. You know what I mean.
The ol’ stress-strain curve gives us a visual representation of what happens on a soft tissue level. Most soft tissues are pliable and have some amount of “elasticity” to them, which is why they can change shape (lengthen, shorten, etc) over time. Muscles and tendons can be stretched exponentially to certain points (i.e. toe, elastic, plastc). The initial change in length is the toe region where we untangle/unravel the criss-cross fibers. Then, the tissue continues to lengthen exponentially to the yield point, meaning the muscle will likely regain its starting length after being stretched. If we continue to lengthen the fibers, then we enter the plastic region where the tissue gains a new resting form. However, if we push the tissue to lengthen even further, it will hit a failure point causing tearing or permanent damage. Then, wooooooooooooo the line quickly falls down and abruptly stops in mid air (well mid graph).
A “strain injury” occurs during the plastic region. That said, depending on the level of strain (grade I-III), the tissue reaches its failure point and tears, breaks, collapses, [insert terrifying, painful-sounding word here].
The psoas, rectus femoris, iliacus and sartorius can be the most likely of the hip flexors to be torn or strained (versus the glutes per say) because of the extended position the hip is in when strained. Dancers, football players, soccer players, martial arts athletes, and yogis tend to be more at risk for strains, but of course this can happen to us all. Think about this injury in the context of a soccer player about to kick the ball. If you were asked to kick a soccer ball as hard as you could, you would start by moving your leg behind you (extension) to create power for swinging it forward (flexion). If you swing your leg too far behind you and you try to generate a high level of force as fast as possible with your hip flexors, then you likely experience a strain or small tear.
How Does A Hip Flexor Tendonitis Happen?
Tendonitis of course is damage specifically to the connective tissue between our muscles and bones. Tendons undergo tensile loading and help transmit force from our muscles so that - for example - our hip flexors can pull our femurs upward or stabilize our joints from hypermobility.
Consider tendonitis an overuse injury, and as we know already, overuse injuries are typically due to repetitive loading with poor mechanical alignment and breakdown of the fibrous tissues. During the gait/running cycle, the hip flexors are active at the time your foot strikes the ground, as your foot moves underneath you until the hip extends and the glutes/hamstrings take over, and most importantly as your leg begins to swing through the air to the next time it strikes the ground. In a world without muscle imbalances and sitting all day, our pelvis stays relatively neutral throughout this process and our perfect posture allows for muscles to activate when/how they should (I’m talking to you glutes….). Unfortunately, that is not the world most of us live in, so our hip flexors have to operate in a pelvis that is probably tilted forward, dropping on the opposite side, or rotated in a way that creates a pseudo leg-length-discrepancy. In any of these scenarios, our hip flexors are undertaking a tensile load outside of a range that is ideal over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over, and over….
I bet you either got tired of reading those 4 repetitive lines, or skipped over it. Imagine how your hip flexors feel? And they cant “skip” or “get tired” can they?
How Does A Hip Strain or Tendonitis Feel?
Many individuals experience sore, aching pain while others complain of a sharp, pinching sensation that occurs when you bring your knee up above your hip joint (i.e. putting on your socks, lifting your leg up, running, sitting for too long, etc.). The pain is typically localized to the front of the hip but can also refer to the groin or outside of the hip. It can also cause you to walk with a limp or change your gait pattern a bit as you find it difficult to bear weight through the injured side.
Often this injury is confused with hip impingement, hip arthritis, or a hernia. Hip flexor strains/tendinopathy has pain during the movement, but subsides in non-aggravating movements/positions. At times, these injuries can “loosen up” or subside with continued movement, but not always - and typically the pain will return with vengeance after activity. Of course, a strain and tendonitis are NOT the same thing. That said, we know the muscle and tendon are a team, and dysfunction in one usually leads to either compensation or dysfunction in the other. So, if you have strained your hip flexor muscle, the tendon will have likely been pulled/”strained” as well. If the tendon is inflamed as is true for tendonitis, then the muscle will not be able to generate force or perform optimally.
Motions that typically aggravate this injury include (but not limited to):
Bringing your knee up towards your chest (i.e. going up stairs, running, biking, walking, hiking).
Lifting your leg off the ground from a supine position (i.e. core exercises, getting out of bed).
Rotating your hip outwards by bringing your knee away from your body (i.e. figure four position, butterfly position).
Sitting for too long and trying to stand up.
Other symptoms relating to strains include:
Swelling or redness
Weakness
Bruising (in grade II/III strains)
Tenderness
What Activities Are Safe with Hip Injuries?
This is the part where I tell you band exercises, yoga, gentle stretching are all things you CAN do. However, caution should be taken if dealing with a more severe strain, which can be distinguished by any swelling, bruising, or redness around the area due to tearing. As always, it is best to consult with a physical therapist or other healthcare provider in order to understand the severity of the injury, obtain any needed imaging, and gather the right tools for recovery. Research continues to support the idea of early tissue loading for proper healing of tendon injuries, usually with the use of eccentric or isometric exercises. It may seem counterintuitive, but running can actually be okay while you recover from a tendon injury if done properly. Emphasis on “if done properly,” which is hard to do for us stubborn running folk. This typically involves cutting back on mileage and intensity, forgetting hill repeats for a while, and even taking days off. Ugh, I know - I didn’t want to say it, but we all knew it was coming.
Icing is helpful for reducing pain and swelling in the area, while heat will loosen any stiffness from tight muscles. Icing may be more beneficial than heat in this instance, but chose whichever provides the most pain relief for you. After all, ice/heat are mostly for pain relief so keep your time to no more than 15-20 minutes. Hindering the inflammatory process TOO much can actually be unproductive long term.
Speaking of inflammation, it is okay to take anti-inflammatories or acetaminophen to help reduce pain and swelling. However, if the pain is tolerable, then see if you can manage the symptoms with ice/heat, rest, and activity modification. These medications are not bad, but can hinder the true healing process of our tissues so it is best to wait if possible. Especially the NSAIDs and Opioids - treat these like you would gas station hot dogs. Proceed with caution and don’t consume too many.
How Long Does It Take Hip Flexor Injuries to Heal?
If you are dealing with a strain, then your healing time will depend on the severity of the strain. Minor strains will take somewhere between 2-4 weeks whereas grade III strains could take 3-4 months before full activity is resumed. Hip flexor tendinopathy can take at minimum 6-8 weeks (likely a few months) which includes time taken for conservative treatment (i.e. physical therapy) as well as the activity modification and “rest” mentioned above. As always, this healing time is very specific to each individual, as factors such as age, nutrition, sleep, stress, and other medical history play a large role in our ability to heal well and heal quickly. Stay patient, stay consistent, and stay hopeful that your hip will return to normal one day!
Helpful Exercises and Stretches for Hip Flexor Injuries
Hip Flexor Stretch/Couch Stretch: Kneel on one knee with the other foot forward in a lunge position. Tuck your pelvis slightly and gently lean forward until you feel a stretch in the front of the hip. Hold for 20–30 seconds, repeat 2–3x per side.
Isometric Hip Flexion: Lay on your back with your legs bent to a reverse table top position. Press one thigh upward into your hand (or a resistance band) while resisting movement. Hold for 20 seconds, rest, and repeat 3-5 times.
Straight Leg Raises: Lie on your back or sit up with your legs out long in front of you. Keep one knee bent, and the other leg straight. Tighten your thigh and slowly raise the straight leg as high as you can. Lower with control. Perform 2–3 sets of 10–15 reps.
Bridges: Lie on your back with knees bent and feet flat. Engage your glutes and lift your hips until your body forms a straight line from shoulders to knees. Lower with control. Do 2–3 sets of 15-20 reps.
Standing Marches: Stand tall and slowly lift one knee toward hip level, then lower and repeat on the other side. Add ankle weights or resistance bands as tolerated. Do 2–3 sets of 10–15 reps per side. This is a more advanced exercise and should not be performed in the initial stages of healing.
Heel Slides: Lie on your back and slowly slide one heel toward your buttocks, bending the knee, then slide it back. Brace your lower abdominals and use your core to help control the movement. Perform 10–15 reps per side for 2-3 sets.
Dead Bug: Lie on your back with arms and legs in the air. Slowly extend one arm and the opposite leg toward the floor while keeping your core engaged. Return and repeat. 2–3 sets of 10 reps per side.
REFERENCES
https://nashville-chiropractor.com/hip-impingement-vs-hip-flexor-strain/
https://www.beaconortho.com/blog/common-hip-flexor-injuries-and-treatments/
https://www.newyorkorthopedics.com/2019/12/12/what-is-a-hip-flexor-strain-and-how-is-it-treated/
https://www.sportsrec.com/223987-hip-tendinitis-and-running.html
https://www.beaconortho.com/blog/common-hip-flexor-injuries-and-treatments/
https://ouhsc.edu/bserdac/dthompso/web/gait/kinetics/mmactsum.htm