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Hi, it is Tom here from Running Physio. Today I want to talk to you about hip flexor pain with three good tips on how to treat it, plus we're going to tackle some of the misconceptions around this.

Now, if you'd like to learn more about hip flexor tendinopathy,

we've got this great tricky tendon series that covers hip flexor and adductor tendinopathy plus lots of content there on peroneal tendon pain and posterior tibial tendon dysfunction. So do check that out.

We had a really good case presented in the Clinical Edge group asking about how we might treat hip flexor tendon pain. And there were lots of great replies but there was quite a lot of confusion about things like diagnosis, what factors might play a role in it and what we should look at here. So I thought it'd be good to talk a bit about hip flexor tendinopathy. I give you three good tips to take away and actually maybe tackle some of these misconceptions.

Hip flexor function

So let's think first of all a little bit about hip flexor function. Now my interest, of course, is in runners, so we'll focus more there, but of course you can apply some of these reasoning principles to any sport. So first of all, let's have a little bit of a look at when the hip flexors are actually working during running.

If we look at some of the research for example from Lenhart et al in 2014, they looked at when we see peak muscle forces for the hip flexors. And I just wanna highlight three key sections.

The first part of this gait cycle is load absorption. The second part is propulsion. And the third part of this running gait cycle is early swing phase.

So what we see then in the loading phase, just after foot strike, actually, there isn't much activity in these hip flexors. So not much activity in iliacus and during the propulsive phase of running, there's also not much activity in these hip flexors either. So they probably don't have a major role in load absorption and propulsion so much. But where we see a peak for iliacus and psoas is in early swing when they're working in their primary role as hip flexors.

So these are muscles that are primarily during running, going to be working hardest in early swing. Now I have included adductor longus in there because that's also working as its role as a hip flexor in early swing as well. So this is quite important when we come back to some of the myths and misconceptions that we'll discuss later.

So first early point are hip flexors, mainly active in early swing during the running gait cycle. Now this study also found that the muscle force in iliacus in particular tended to increase with an increase in step rate. Now we know that actually increasing step rate can be quite useful to reduce the stress on a number of different tissues.

If you increase step rate by about 10%, you can reduce the load on the hip, the knee, the tibia, the achilles, glute med. Potentially lots of different structures will be working less hard if you increase the step rate by about 10%. But the downside is it tends to increase hip flexor load and what also really increases hip flexor load is speed. Now, this may be partly because as we run faster, the step rate increases, particularly as we get up towards sprinting. So that's the second point about our hip flexor function. If we look at the research from Dorn et al, this shows this quite nicely, the peak muscle forces for iliopsoas really increase dramatically with speed, particularly towards sprinting.

So that step rates going up, we're having to drive those hips through harder, and we're finding there's an increased workload for iliopsoas in that situation with increased speed or potentially with increased step rate. So some thoughts there around the function of the hip flexors.

So next up, let's think about these three key tips.

Tip 1 - Is it a hip flexor tendinopathy?

So number one, if you have an endurance runner and you feel they have a hip flexor tendinopathy, the first key point is it might not be a hip flexor tendinopathy because that hip flexor load is low at these endurance speeds. So true hip flexor tendinopathy in an endurance athlete doing these lower speeds is fairly rare.

In a sprinter, yes, it can certainly be a problem. You can see why that might be the case. We see this big increase in load on the hip flexors as we run faster, but it isn't really a common finding in endurance athletes at slower speed. Now, what that should make us think then is, is there a differential diagnosis?

And I'm sure many of you beware. One of the main ones we'd be concerned about is a femoral neck stress fracture, because that too can cause us pain in the anterior thigh. It can mimic hip flexor tendinopathy. Even sometimes you'll get irritation of those hip flexor tendons as a secondary effect of a femoral neck stress fracture and that then unfortunately can be a bit of a red herring. It seems to be a hip flexor, but actually there's an underlying bone stress injury.

Now, again, think back to function. When are those hip flexors working? They're predominantly active in swing. They're not managing the loading response, so well, certainly during running, I suspect also likely to be the case during walking.

So if you have a patient whose symptoms are mainly during weightbearing, during walking, during impact, that would wave a bit more of a flag to think, okay, that's more consistent with a bone stress injury, possibly femoral neck stress fracture, particularly if they've got any of those risk factors we've talked about in our other videos, things like a previous history of bone stress injury.

Perhaps they have history of inadequate nutrition or they've got low BMI, any of these factors that are going to influence bone health should make us suspect bone stress injury rather than a hip flexor tendinopathy in this situation. And it would be then appropriate to investigate that with an MRI considered the gold standard if you suspect a femoral neck stress fracture.

Of course, there are lots of other things that will cause pain in that region. Let's not go straight to that. Intraarticular hip pathology will often cause pain in a similar region to these hip flexors. If you're getting pain, for example, at end of range flexion or in internal rotation, or your flexion abduction, internal rotation tests, that would lead me a little bit more towards intraarticular pathology.

So that's the first key point. It may not be a hip flexor or tendinopathy. Do testings out thoroughly, consider bone stress injury, consider interarticular pathology, and a and other potential causes of pain in this region.

Tip 2 - Rehab of hip flexors

Tip number two is, let's say we think it is a hip flexor tendinopathy and perhaps this person's been doing some sprinting work and that seems to have triggered their symptoms.

Perhaps you've had an MRI that suggests this, or helps to rule out one of those other differentials if we want to load it, it's best in the early stages not to load it in hip extension or abduction positions because that tends to irritate those hip flexor tendons. So in the early stages of management, make sure you are not loading them in those stretched positions. And if they've gone off doing lots of stretches, maybe they're trying to do Bulgarian split squats or side lunges, they're really trying to get in there and give it a good stretch out. Often, it's quite a good idea to say, let's back off of those because like most insertional tendinopathies, it just tends to irritate it.

So in early stage management, I might be looking at doing, if it's particularly irritable, some isometric hip flexion work in a little bit of hip flexion range. So well away from hip extension. I may also include some work for the other muscles around the trunk, may be the stomach muscles, may be the adductors as well isometrically, if that's all they can tolerate in the early stages. Then we can move on to more dynamic work to strengthen the hip flexors and towards the later stages when they're non irritable, we can bring in those more stretched positions if they're indicated, if someone wants to be able to load in those positions. So then we might bring in our lunges or our split squats or our side lunges, et cetera. But as ever, based on symptom response.

So tip number two here, be cautious about loading into stretch positions of hip extension or hip abduction, if you think it is a hip flexor tendinopathy.

Tip 3 - Other muscle groups to include in rehab

And then key point number three, is think about the other muscle groups that you can strengthen alongside it.

Now, I've touched upon this a little already, but we can see when the hip flexors are functioning in early swing, when iliacus and psoas are functioning then, we also see the adductors, particularly adductor longus working as another hip flexor. So I think it makes sense often to include some adductor strength work alongside your hip flexor strength work as well.

Strengthen those two muscles up together, maybe alongside some stomach strengthening work as well, if you feel that, that's appropriate and anywhere else that you feel maybe a little bit weaker, may be relevant to their symptoms. So it's not just about the hip flexors, consider the abductors, the trunk muscles as well, as part of your rehab.

And then you can gradually progress the load. And in terms of your return to running, as you can see from what we've discussed, it may require a graded return to higher intensity work, where that stress on the hip flexor is quite a lot higher. So those are our kind of three key points to take away.

Just to recap them. Point one was, do consider the differential diagnosis, particularly femoral neck stress fracture because true hip flexor tendinopathies in endurance athletes are quite rare. Point number two, load away from those stretch positions initially. And point number three, consider the other muscles around that region, like the adductors and the stomach muscles.

Common misconceptions

So let us come on to some of the misconceptions around this. Now, those people that shared ideas on this please don't take this as any way as criticising them. All I would ask is that if you have evidence to support some of these ideas that we are going to cover, please let us know. None of us, including me, know everything about it. So there may be things that I've missed, but some of the things that were brought up there, I would say if we reason things through are not likely to be key factors in hip flexor tendon pain.

1. Pronation

So the first one that was brought up as a suggestion was, look at pronation, look at over pronation during running.

Well, Let's reason that through, firstly, we know that it's a tricky topic. We know it's very difficult to define what is over pronation, and that pronation is a normal movement to help us absorb load, but it's predominantly happening in the load absorption part of running. When we are expecting the hip flexor load to be low, so to my reasoning process, it's hard to connect a slightly pronated foot posture with increased stress on these hip flexors.

So personally, I wouldn't consider that to be a factor. The hip flexor load is at its highest when the foot's not

in contact with the ground during early swing. So personally, I don't think foot posture is going to make a big difference and it's worth challenging some of these because we can end up going down a little bit of a rabbit hole with these getting pulled off in directions that aren't actually that helpful for the patient.

Firstly, I would challenge pronation as a factor. If people listening in disagree, you've got evidence to suggest, otherwise, please share it. I will happily admit that I'm wrong. But personally that would be my reasoning process there.

2. Firing order

Point number two was firing order. So someone suggested again, helpful suggestions.

How about looking at the firing order? Perhaps glute max is kicking in before the hamstrings, and that's an issue. Now, again, this is another one I'm trying to work out why glute max and hamstring firing order would be relevant here because those muscles, particularly hamstring, their peak activity is at terminal swing, slowing the leg down before the foot strikes the ground.

Not really at that point in early swing when we are getting a lot of hip flexion. But also this idea of firing order is a tricky one. We can't really reliably by watching a patient move or placing our hands on them determine firing order. We can't. We cannot also say there's a correct firing order, that one muscle should kick in before another. That's been shown in the research. There's quite a variety in how that happens. So again, it might be a bit of a rabbit warren. We get involved in assessing this, making assumptions that it's important for the patient, sending them off, trying to do some work on firing order and honestly, I think perhaps confusing them a bit when it probably isn't a big piece of the puzzle.

Firing order for me, I'm personally being totally honest, I don't think we can tell firing order. I don't try and assess it with my hands. I don't really think it's something that I personally would spend a lot of time trying to look at. I'd rather look at other things that we can change.

3. Weak transversus abdominis

Third one was, what about weak transversus abdominis? Again, this is a very difficult one for us to assess. Can we actually really detect a weak transversus abdominis? And is it really going to make a big difference to the load on the hip flexors? My suspicion is no, I don't think we can really assess transversus strength very accurately in isolation or its activation patterns, and I can't really reason through why that would be a big factor in the load on the hip flexors.

Think back to our graph, look how much that stress on the hip flexors is increasing with increased speed. Surely, adjusting their training intensity is more likely to reduce the stress on that tendon than making small changes to the activation pattern or the strength of the muscles in transversus abdominis. Again, we want to have that reasoning process involved.

4. Rib alignment and breathing patterns

And the final one that was suggested, and again, good to have these suggestions and I'm totally open to evidence here, is that we should be looking at rib alignment and breathing patterns and that they affect hip flexor load. I'm not aware of any research that is shown this, so if you are, please share it with us.

But again, I think this is a little bit of a path we can end up going down that doesn't really work for our patients, so I would probably not spend a lot of time looking at foot posture, firing patterns, transversus abdominus or rib alignment and breathing. Personally, I think there's less to be gained there. If you have someone with pain in that kind of hip flexor region, I think we are much better off being thorough in our assessment to determine what the diagnosis is. And then to do a progressive program to address their rehab needs, to strengthen them where they're weak, to include the hip flexors, adductors, and trunk, if that's relevant to the patient, and then gradually return them to their goal activity with a particular care taken over intensity and speed, because that's likely to expose that tendon to more stress.

Okay. I hope that's useful for you. As I said, we've got this great tricky tendon series that I've linked to that was great fun for me to put together. I must admit there are some photos in there of my feet, but other than that, I assure you it is pretty good. I think you'll find there's lots of useful information for you to take away there, and it is free, so do check that out.

And as I said, maybe if you disagree what we've talked about , maybe I've been a bit harsh on some of these misconceptions. Let me know in the replies and comments. This is all about being curious and exploring different areas rather than dismissing things altogether. So let me know perhaps there's some evidence I've missed or reasoning process I'm not up to speed with.

Okay. Thanks again for listening. Bye for now.