Art of Prevention

Challenging Fitness Myths: The Clamshell Exercise's Glute Misconception and Effective Hip Strength Alternatives

• Art of Prevention

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Prepare to have your fitness beliefs rocked as we expose the clamshell exercise's hidden inefficacy! I'm taking you on a myth-busting mission to show why this popular rehab move might not be the powerhouse for hip stability it's often touted to be. With evidence from a 2019 study by Moore et al. that challenges the clamshell's ability to effectively work the gluteus medius and minimus, you'll learn why it's time to rethink this go-to exercise. This episode isn't just a critique; it's a revolutionary look at how we can optimize musculoskeletal rehabilitation and prevent injuries more effectively.

This enlightening discussion doesn't leave you hanging on alternatives—we're talking about powerhouse exercises that actually deliver on the promise of stronger hip abductors. Imagine elevating your workout routine with moves like the running man and standing hip abduction with extension, all while steering clear of injury pitfalls. By phasing out the clamshell, we're looking at a future where time in the gym is never wasted, and where every rep counts towards building resilient, injury-proof bodies. Tune in to shift your perspective and fortify your fitness approach with techniques that truly target those crucial hip muscles.

References:

Moore, Damien, Adam I. Semciw, Jodie McClelland, Henry Wajswelner, and Tania Pizzari. 2019. “Rehabilitation Exercises for the Gluteus Minimus Muscle Segments: An Electromyography Study.” Journal of Sport Rehabilitation 28 (6): 544–51.

Moore, Damien, Adam I. Semciw, and Tania Pizzari. 2020. “A SYSTEMATIC REVIEW AND META-ANALYSIS OF COMMON THERAPEUTIC EXERCISES THAT GENERATE HIGHEST MUSCLE ACTIVITY IN THE GLUTEUS MEDIUS AND GLUTEUS MINIMUS SEGMENTS.” International Journal of Sports Physical Therapy 15 (6): 856–81.

Michaud, T. C. (2012). Human locomotion. Thomas Michaud. 

alternative to the clamshell: 
https://youtu.be/RW14HMNndog?si=C8SV4nqaEKorKN6E

If you have listened to this podcast for any length of time you know that strength training is crucial for runners. However a major obstacle for many runners is not know what to do once they get to the weight room. This PDF seeks to change that. It will arm you with the tools you need to effectively strength train to get the most out of your runs. 

use code PODCAST for a 20% discount at checkout at artofprevention.org/runners

Speaker 1:

Hello everyone and welcome to another episode of the Art of Prevention podcast, and today I'll be taking a different tact of the podcast. Instead of talking specifically about injury prevention, I'm going to be talking about basically my least favorite ineffective exercise, and that exercise is the clamshell. So I don't know why I developed this pure hatred and basic disgust for this exercise. However, what really put the nail in the coffin for me was when I actually perused the literature, or I came across literature years ago that elucidated how ineffective this exercise can be. And yet, in spite of this ineffectiveness of this exercise, what I see time and time again is this exercise being prescribed to individuals that are suffering from hip pain, knee pain, and they're being prescribed this exercise for various reasons, but through research, we have found that those reasons are not being facilitated or not being improved upon by this exercise. So today I'm going to be talking about the clamshell exercise, what it is meant to do, why we know that it doesn't do this, why it sucks, basically, and then I'll give some alternatives and then, at the very end, I will tell you some patient populations that may actually benefit from this exercise. But one thing that I know and I see is that the patient populations that may benefit from this exercise is not the only population that is being given this exercise. So if you're a clinician or you're a coach and you're okay with the status quo and just doing things the way that you've always done them, don't listen to this interview or don't listen to this podcast. If you do listen to this and you're okay with the status quo and you're just going to keep giving out clamshell exercises, you're either going to resent and not like me, or you'll resent and not like yourself, because the evidence is piled up against this exercise and I hope you enjoy.

Speaker 1:

So the first question that needs to be answered is what is the clamshell exercise? So the clamshell exercise is a classic exercise. I think that you know. You've get taught it like the first day of PT school or something like that. I don't know, but that's what it seems like. It's the most basic exercise in basically the entire realm of conservative musculoskeletal rehabilitation and how you perform this exercise, as you lie on your side and you have your knees bent to about a 90 degree angle and then you simply rotate the top knee upwards. Now there are many variations of the clamshell exercise and it's actually, or it is indeed a variation of this clamshell exercise that I give to my patients. However, it's the opposite, basically, of how it's traditionally done. So when you're lying on your side, the clamshell exercise is strengthening quote unquote strengthening the top leg by raising and rotating that knee upwards.

Speaker 1:

Now, what is this exercise meant to be doing is question number two. This exercise is supposed to strengthen the hip abductor, so the muscles on the outside and back of the hip, namely the gluteus medius and the gluteus minimus. Okay, so that is what we're supposed to be doing with this exercise strengthening gluteus medius and gluteus minimus. Now, now we can talk about why this exercise sucks, because there's actually a decent amount of high quality evidence that shows that this exercise does not do what it's supposed to do. And even if it were valid and doing what it was what I'm quote supposed to do, then it honestly still wouldn't be an ideal exercise choice, an ideal exercise prescription for many individuals, and we're going to talk about many of those reasons now. So why does it suck? Well, frankly, it just doesn't activate those muscles. It does not activate the gluteus medius and it does not activate the gluteus minimus, and I have two studies that show this.

Speaker 1:

The first study that I want to talk about is by Moore et al in 2019. And this study actually utilized indwelling needle electrodes to measure the electrical activity of the muscles in question. And not only did they measure the activity of the muscles, but specific segments of those muscles, so they actually looked at the anterior bundle of the gluteus medius, the middle bundle and the posterior bundle of the gluteus medius. They also did a subsequent study on the gluteus minimus, looking at the anterior and posterior bundles respectively, and they compared the clamshell exercise to five other exercises, so six exercises total. Those exercises included the clamshell, obviously, but also the run man, abduction and lying abduction and extension and standing with a resistance band, as well as the single leg bridge and the single leg squat, and they wanted to see what are the best exercises for targeting these all important hip AB ductors and we'll talk about the importance of the hip AB ductors near the end of this episode and what they found with this study a really cool study with high amounts of internal validity like what are we measuring? We're measuring the electrical activity and if this quote unquote activates the glute med and the glute min, they found that when we're looking at the, especially the anterior or the front bundle and the middle bundle of the gluteus medius, the clamshell exercise basically doesn't even show up on the graph.

Speaker 1:

Let me say that again, the clamshell is almost zero activation. If you want the specific numbers 3% maximum voluntary isometric contraction of the anterior segment, 3% out of 100, okay. 13% maximum voluntary isometric contraction of the middle segment and then 23% of the posterior segment. So a small amount of MVIC. Maximum voluntary isometric contraction was defined in a separate study at 40%. So that's a small amount. That's like the lowest criteria for this actually activating a muscle. And we found that this clamshell exercise didn't even hit near 40%, barely even hit halfway to a normal amount of activation in these studies. So we know what's going on in these studies. It's not like something crazy is happening and we just know that it's not working.

Speaker 1:

Now we can also compare that to all these other exercises and what we found was that this was indeed the very worst exercise for activating these segments. So you could literally open up a random book in a PT journal or in a PT exercise book and any exercise that you find for the lower extremity would probably be better than the clamshell exercise. So if we look at the running man exercise, where you're standing on one leg and then literally just flexing it and extending the other hip. That's better. Literally, just lying on your side with a straight leg and lifting up that straight leg is better. Standing up and then pushing your leg to the outside is better. A single leg bridge is better. A single leg squat is better. Any exercise is better than the clamshell exercise. Yet the clamshell exercise is the one that's probably the most prescribed for strengthening the hip abductors. And now you guys know why I'm so frustrated with seeing patients that are given this clamshell exercise and then coming to see me because they failed quote unquote failed conservative management, failed conservative management.

Speaker 1:

On to the next study. So in 2020, damien Moore and his team. They said, well, let's not look at this really small sample size with high internal validity. Let's now do a systematic review of randomized controlled trials. They're not randomized controlled trials because they're just measuring activity. So systematic review and meta-analysis, looking at papers that are trying to establish if these exercises actually activate the muscles that we are quote unquote targeting. So in this study, they looked at 10 papers that measured the activity of the gluteus medius and the gluteus minimus with these exercises and they found, yet again, across 10 papers, that the clamshell exercise still sucks. So it still does not get the activation required to actually strengthen the muscles that we are trying to quote-unquote target or quote-unquote isolate with the clamshell. So we know from small sample sizes that are really good, we really know what's going on, to larger studies, systematic reviews and meta-analyses even that compile many of these articles together, and we still find that, even with these higher level and more gold standard research criterion that it's not working. It's just not doing what we would like for it to do.

Speaker 1:

Now, from a theoretical standpoint, there are also detractors or negatives to the clamshell exercise. One of those negatives is that this is an open chain exercise. So the difference between open and closed chain is basically support points. So when I'm lying on my side and I'm lifting up or rotating that knee upwards, it's open chain. So in this scenario, I'm using theoretically the glute med and glute min segments to, in an open chain fashion, rotate my knee upwards, but the way in which we actually utilize these muscles to protect areas like our knee or our ankle or our hip itself, is actually in closed chain. So it's actually the opposite of this exercise.

Speaker 1:

So when do we need these hip abductors. Well, we really need it when we're walking, when we're running and we need it when we're pivoting, so when our foot is on the ground. That is when we need to be able to utilize the gluteus medius and the gluteus minimus. And when our foot is on the ground this now turns from an open chain exercise to a closed chain exercise. So the chain, if you will, the muscular chain, is now closed because that support point is on the ground, as opposed to our leg being in the air. So, open leg is in the air, closed, the leg or the foot is on the ground.

Speaker 1:

So in the scenario, even if it did target those muscle segments, it still would not be an ideal exercise. Reason being it's being performed in the open chain. When do we want to activate these muscles In the closed chain? So that's one reason also why, like the run man exercise, the standing hip abduction with extension, the single leg bridge and the single leg squat would all be superior exercises because we are exercising these muscles in a closed chain fashion. So if we look at the mechanism behind something like an ACL tear or something along those lines, it's when the foot is on the ground. So a non-contact ACL injury, which occurs in about one in 20 or one in 25 female soccer players. There's basically an epidemic of ACL injuries in female soccer players and female handball players and female lacrosse players, etc. And that's happening while the foot is on the ground, so that's happening in closed chain. Thus, it would be better if we do train in closed chain. So there's another reason why the clamshell still sucks.

Speaker 1:

Now we have tons of alternatives. It's not like this is a tricky job finding exercises that activate the gluteus medius and gluteus minimus. I've already named five exercises that are far superior in activating the hip abductors the glute med and glute min. So again, the running man, sideline hip abduction, standing hip abduction with extension with a resistance band, single leg bridge and single leg squat. But even if we go to something simple like a double leg squat or a deadlift or an RDL, all of these are going to be superior to this glute med supposed exercise like the clamshell.

Speaker 1:

Now, the last thing that we have to ask ourselves well, really, the first thing that we need to ask ourselves is are we doing any harm with this exercise? And directly, frankly, we're not doing any harm at all, mostly because we're not really doing anything. So does the clamshell exercise do harm specifically? No, it does not do direct harm to the hip, nor does it do direct harm to the knee, the lower extremity, the back, etc. However, my theoretical question is does it do indirect harm? So would it indirectly harm someone to be doing this exercise in lieu of or instead of some other more effective exercise? Well, let's think about it for a second.

Speaker 1:

We know from multiple studies that hip abduction strength deficits are associated with get ready for a list here ACL tears, non-contact ACL tears, specifically femoroacetabular impingement or FAI, labral tears, iliotibial band syndrome, patellofemoral pain syndrome, etc. The list goes on. Now there is a bit of a chicken or egg scenario when it comes to pain and the inhibition of muscles. So the question always is is it the inhibition of muscles that led to the pain, or was it the pain in these extremities or joints that led to inhibition of muscles up the chain, like these glute med and glute med muscle segments? Now, in that first example, the ACL tear, those were actually baseline measures. So what they found with baseline measures is weakness in the hip abductors. This is a Chris Powers study, by the way. They found that weakness in the hip abductors was something that had predictive value for seeing or predicting who was going to tear their ACL during that soccer season. I believe it was in soccer players.

Speaker 1:

Now, with the other things usually those are retrospective studies, or taking somebody with femoral acetabular impingement or with a labral tear or with IT band syndrome or with patellofemoral pain syndrome, and then measuring their hip abductor muscle strength, so measuring the strength of those glute meeting glute min muscle segments, and in that then we really do have that chicken or egg scenario of which one is causing which. However, if we look at it just from a theoretical standpoint, there is nothing wrong with getting strong and there's nothing wrong with staying strong. Having good strength in the hip abductors or the posterior lateral musculature of the hip is going to be beneficial from a performance standpoint as well as in an injury prevention standpoint. So could this be causing indirect harm? Well, one we know now the clamhell exercise is a waste of time. So this is not proper utilization of patient resources.

Speaker 1:

One of the most important resources that we have on this earth is time. We also know that if someone is doing the clamshell exercise, that they're wasting their time, but their time could be used more effectively doing other exercises like the ones mentioned as alternatives. So if we are substituting these effective exercises for an ineffective exercise, then we are wasting time, wasting patient resources and we may be just fatiguing someone not necessarily fatiguing those muscles because they're not activated, but fatiguing someone in that we are fatiguing their central nervous system from just performing exercises, monotonous exercises that are frankly not doing anything. So we could be adding fatigue, even if it's just neurological fatigue or CNS fatigue, from just performing volume of exercise rather than performing fewer amounts of exercises that are effective.

Speaker 1:

Now, if somebody's looking up like how to do these exercises and is doing these exercises, then they may also have a false sense of security and a false sense of confidence in their hip muscle strength. So in that scenario they may go out and do a lot of things like running, jumping, pivoting sports, et cetera, thinking that they've done the necessary things to strengthen the posterior lateral hip muscles, when in fact they've actually just been wasting their time and may still just have that weakness in the posterior lateral hip muscles, when in fact they've actually just been wasting their time and may still just have that weakness in the posterior lateral hip muscles, which can actually lead to a ton of frustration amongst patient populations. And this is when people will quote unquote fail conservative care or maybe that makes them fail rehabilitation. So we know that the ACL anterior cruciate ligament re-terror rates in soccer players is about one in five, which frankly is a very high number. Now, is this because surgeons aren't doing a good job? I don't believe so. I believe surgeons are doing an amazing job with ACL reconstructive surgery and then a lot of PTs do amazing job with rehabilitation. But I do still see a lot of patients be given this, or a lot of patients, many patients are given this clamshell exercise as a means to strengthen the muscles on the outside of the hip. Now we know from those baseline tests in the CRISP-HOWER study that ACL tears can be brought on or we can increase the risk of ACL tears with weakness in the hip abductors. So if we're talking about re-tearing in the knee, re-tearing of the ACL in the knee, then having weakness in those posterior lateral muscles of the hip like the glute med and glute min, that's really going to predispose someone because one they have a prior injury. What's the most predictive of an injury? The most predictive factor for an injury? That would be previous injury as well as weakness in those muscles. So we could be instilling a false sense of confidence and a false sense of security in individuals just by performing this exercise. That is ineffective. So I actually believe that not doing a great job in exercise prescription, not doing a great job in giving out exercises, can actually cause indirect harm to patients as well as athletes as well as everyone that's basically given this exercise. So if you're a clinician, don't waste patient resources, don't instill a false sense of security and don't waste their time. Don't waste anybody's time with this exercise. All right Now, probably the hardest or most difficult part of this episode.

Speaker 1:

Who could benefit? So is there a patient population that could benefit from this clamshell exercise? And the answer is yes, probably so. I believe that there are better ways to facilitate this, but if we think about it, this could just be an exercise to get range of motion back into the hip and in the immediate post-surgical population, where they still have stitches and you're afraid of that wound opening up. In that scenario we're just working on range of motion and motor control anyways, so maybe that could be good. I mean, I would honestly prefer like a dead bug position, so being on someone's back and then really focusing on hip motion and range of motion and cortical or voluntary control over that motion on the back as opposed to rotating while on the side, but could it be beneficial? Maybe side. But could it be beneficial? Maybe the significantly overweight population that could also be a patient population that could benefit, just because it's literally something. So, just because it's some movement, it could benefit some populations that are unable to perform something like single leg stance or sidelining hip abduction, just because of the sheer weight of the leg in conjunction with weakness of that musculature. So those are the two populations that could potentially benefit from this clamshell exercise, and that's all that I have today.

Speaker 1:

So I really don't like to talk smack on practitioners or talk smack about really anything, especially in a public format. However, this clamshell exercise is the exercise that should mostly die. So if you're someone who is prescribing this exercise on a regular basis, I truly encourage you to take a step back and reflect on and look at some of the studies that I talked about and think is this actually a good utilization of my patient's resources, whether they're coming in and paying you for rehab or if we're just talking about that patient's time at home? I'm really not a fan of this exercise. I cannot think of the last time that I prescribed this exercise to someone, and I think that we as clinicians could be doing a lot better. If you are a coach and you are prescribing this exercise, do literally any other lower extremity exercise and you'll be better off than doing this clam exercise. So if you're a coach whether that's in person or virtual like stop sending out this exercise. I mean, it's just not doing what someone on runner space or runner's world told you that it is doing.

Speaker 1:

I have literally had people come into my office that have done thousands upon thousands of clamshell exercises. And then I do my personal favorite, the DNS hip uprighting exercise, which is just an inversion of the clamshell where, instead of lifting up the top knee, you're pressing the knee as you rotate forwards into the ground in order to raise up the hip. And I'll show a link to that video as well, because it's truly is one of my favorite exercises, not only because it actually is closed chain and it does actually activate the hip musculature, but because it also incorporates the core activate the hip musculature, but because it also incorporates the core. It is a global movement pattern and there are other benefits for that way of doing things as well. If you are an athlete and you're doing this exercise, stop wasting your time. Do something else. Do literally anything else and you will be better off and you will have a lower risk of injury. You will have more time to do probably the sport that you love, whether that's running or soccer, or pivoting or whatever.

Speaker 1:

And that concludes my episode for today. So thank you for listening If you listened all the way through this to my long, tangential rant. Thank you for coming to my soapbox lecture today and stop doing clamshells. I hope you all have a great day. I hope that you enjoyed this episode of the Art of Prevention podcast. If you did enjoy and or benefit from some of the information in this podcast, please be sure to like, subscribe and share this podcast or please give us a five-star review on any platform that you find podcasts. One thing to note that this podcast is for education and entertainment purposes only. No patient is formed and if you are having any difficulty, pain, discomfort, etc. With any of the movements or ideas described within this podcast, please seek the help of a qualified and board-certified medical professional, such as your medical doctor or a sports chiropractor, physical therapist, etc.