“Tight” Hip Flexors Mean Less Glute Max Activation?

Janda, lower crossed syndrome, glutes. These are all powerful words to some people. Buzz words. Words that are pregnant with meaning, context and significance. For some people, they define who they are and what they believe in. 

So why am I writing this? 

This blogpost is inspired by events that have taken place and dotted throughout my career, probably from over a decade ago and I keep getting regular slaps in the face that challenge my beliefs. It probably came to a head during my Specialisatoon training and a ding dong battle with Greg Lehman where he was dinging and dinging me much more than I was him. I limped away from that battle apparently resolute in my ways but the seeds had been planted and that interaction was probably a tipping point to me rethinking how I practice and why I do what I do (thanks Greg). 

I am writing this to illustrate how we need to be careful of the stories we tell ourselves to explain what we observe. Science is about having an idea and then doing your best to disprove it, NOT trying to confirm your ideas. When you have tried to beat your idea up and it survives, MAYBE the idea is significant. 

Quite often we tell ourselves comforting stories that fit our beliefs and philosophies on how the body works. We take comfort in the results we get. We take comfort that whomever taught us said that it would work for these reasons and they are smarter than is. We take comfort in “research” that seems to support these ideas. 

I used to be terrible like this. I mistakenly thought that because I got great results, it proved that the methods I used and the reasons why I thought it worked were correct. I was wrong. Now, I am less terrible than before but still bad. It is a constant struggle to challenge my beliefs. When you kill off one type of narrative (story), you HAVE to replace it with another one, even if that story is “I don’t know”. 

The struggle is real people! It is like being a recovering alcoholic working in a bar. The majority of the population, my peers, other healthcare professionals…everyone, believes in some sort of narrative that is incorrect, especially ones that relate to what is wrong with the body, how it works, how it gets better and how I help people get better. Everywhere I turn, people believe the things I used to believe and it is tough not to just slide back into the old beliefs. I might still do things that look like the old beliefs but I tend to have different reasons for doing them now. They may not be the correct ones but I think they are better reasons than before. I have had to let go of a lot of beliefs and challenge the material taught to me by people I greatly respect. It is not easy to do that. 

Now, don’t get this idea that I am trashing the work of Janda or anyone else out there. I’m not. In fact, I applaud the work and effort that has gone into trying to explain our world and our bodies. I may not believe in Traditional Chinese Medicine but I can appreciate that they are simply trying to codify their observations. We do something and we observe a result and we try to explain it. That is science. 

The problem is when we cling to the story despite the evidence. I truly believe getting the results for my patients are important but it is a responsibly I have to explain it as best we can using science…sometimes we can’t. That’s ok for now. We must keep trying though. When I or one of my colleagues or patients starts to cling too tightly to a story/method/technique/philosophy, I have to recognise that I do the same things. 

I have challenge my beliefs daily. I wrestle with this stuff and wish I were smarter. I tend to cheat and just surround myself with smarter people but that really isn’t the solution because the smart ones struggle too! I actually have to learn to be better at challenging my beliefs, not rely on others and just trust what they say because then I have to challenge THEIR beliefs too! Still, while I will forever be a padawan, I can learn from the masters. The example below is one such instance where I learnt a lot from one interaction. 

The event that inspired this blog post

A study was done that appeared to show a correlation between hip flexor “tightness” and Glute Max and Glute med activation. You can find the study here…

Mike Reinold wrote a blog post enthusiastically supporting the study and its findings. I don’t blame him to be honest because it is the easiest thing to do, especially when you and the study authors believe in the same story/philosophy (in this case Janda and the lower crossed syndrome). You can find his post here…

Adam Meakins (a Physio from the UK), in a Facebook Post, asked Greg Lehman (a Chiro and Physio from USA) what he thought of the study. Here are Greg’s thoughts…couldn’t have said it any better myself (probably would have done a much worse job and missed many points which is why I just quoted Greg!)

Alright. There are few issues.

1. There might be some mistakes in what they wrote in the results. The authors write “A statistically significant strong and negative correlation existed between hip flexor length (as measured by the Thomas test) and GMAXmuscular activation (r = -.651) for female subjects but not for males.”

This means that decreased hip extension is related to higher Gmax activity. What I think they meant was that gender is related to higher glut max activity.

They go on to write that hip flexor length is correlated to Gmax activity with an r=.417.

This is not a strong correlation (not statistically significant) and may be spurious.

2. An example of a spurious correlation would be that GMed activation is also related to hip flexor length with an r =.396. Why shouldn’t we focus on this? Because it doesn’t fit with the narrative. Would anyone argue that reciprocal inhibition is somehow working to inhibit the GMed from the hip flexors. They aren’t agonists-antagonists. Makes no sense. Just a fluke.

3. Massive variability in the data. You’ll notice that women had peak GMax EMG greater than 80%MVC while the men had EMG around 60%. Does this mean that all the men had inhibited Glutes compared to the women. NO

Percentage EMG is calculated with a numerator (the activity found during the Kettlebell swing) and the denominator (the activity found during the max contraction). The women were just functioning at a higher percentage of their maximum contraction.

But notice that the women had higher levels of hip extension during the Thomas Test. Perhaps someone should argue that the peak activity found during their maximum contraction (the denominator) was low and therefore “inhibited”. Thus they had a greater percentage during the Kettlebell swing because they were “weak” during the maximum test.

You can spin this stuff either way. You could argue that increased hip extensibility was related to decreased activity during the max contraction therefore the people were weaker and had to work harder during the KettleBell Swing. This is wrong but goes to show how these types of studies (through no fault of the authors) can’t shed insight into these ideas.

4. The correlation was not statistically significant.

5. If the hips flexors are truly tight wouldn’t you have to have more EMG activity to “power through” their resistance during hip extension. Of course not, but again this points out how biomechanical reasoning can justify different things. 

6. None of these people had “tight hips”. All of them had hip extension where the thigh went below parallel. Where do you draw the line of what tight is? at what level of “tight” do the hip flexors start inhibiting the glutes if this actually happens.

7. Why would the hip flexors inhibit the glutes during an activity that primarily sees the hip in a flexed position. The hip flexors aren’t even being tensed – they are shortened. They aren’t even turning on during this activity.

Hope that helps.

Greg has just released a blog post literally as I was writing this and you can find it here. 

Conclusions?

  1. Don’t believe everything you read. 
  2. Challenge your beliefs, daily!
  3. Don’t look to confirm your beliefs but rather look to disprove them
  4. Learn from smarter people like Greg and Adam. Sandy Hilton is another I have learned a lot from. 

Thank you!

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About Antony Lo
Antony Lo is an APA Musculoskeletal Physiotherapist based in Sydney. His website is www.MyPhysios.com.au. He specializes in the management, treatment and prevention of pain and dysfunction, particularly of the pelvis and ribcage. His sub-specialties include Crossfit and Exercise Performance Optimization, Ante-Natal and Post-Natal Care and difficult cases that have failed treatment elsewhere.

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