This is episode 448, with Professor of Biomechanics at the University of Calgary, an advisor to running startups and an expert on how mechanical load affects the body, Professor Brent Edwards.
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My guest today is Professor Brent Edwards.
He's a member of the faculty at the University of Calgary who specializes in how mechanical load affects the body.
His research focuses on how mechanical loading influences musculoskeletal health and injury risk.
In addition to running experiments in the lab, he's also working with the smart shoe company Avello to help them figure out how to keep runners healthy.
His expertise ensures Avello's impact metrics reflect what is really happening with your stride, so you can learn from it and train smarter.
You can pre-order a pair of smart running shoes at AvelloRunning.com if you want to check them out.
Our conversation today is an attempt to take the lab results and make them practical.
We discuss how Brent thinks about impact examples of repetitive stress, whether soft surfaces actually reduce impact forces, how we can learn from Brent's research to stay healthier and a lot more.
If you'd like to reach out with questions, he has made his email available and you And now, please enjoy my conversation with Professor Brent Edwards.
Here we are, Brent Edwards.
Thank you so much for joining me.
Thanks, Jason.
Happy to be here.
All right.
You are a very interesting guy.
You study the role of impact forces on musculoskeletal injuries.
You're advising companies in the running space on how they build products that contribute track, impact and force.
And so I want to talk to you about the role of impact, because running is such an impact sport that if we can better understand how our body is navigating all the forces that it's experiencing, then I think we probably design better training and probably keep us a Let's start super broad.
You study how impact forces affect the body.
What's an example of, you know, a quote-unquote good impact force?
And what's an example of a potentially harmful impact force?
So quick clarification, I don't only study impact forces.
I study kind of all these different types of forces that influence the musculoskeletal system.
And so...
Maybe it's just better to really first just define what an impact force is, because runners love to talk about impacts and impact, loading and minimizing impact and injuries associated with impact and all these things.
So I think...
When it comes to running biomechanics, and when we use the term impact forces, we mean something very, very specific.
And we're talking about this instant.
It's not just a single instant.
It's this event that happens when your foot hits the ground, when you're running or walking.
There's impact forces in walking and jumping.
And we can characterize the force between the foot and the ground using what we call force platforms, as sort of sophisticated scales essentially, where we can quantify the forces between the foot and the ground.
Yeah.
And so we get people to run over a force platform.
You can see this little blip kind of thing that happens when their foot hits the ground.
It happens very quickly, within 50 milliseconds or so after the foot hits the ground.
And so that's what we call an impact force, the magnitude of impact.
Loading, the amount of force associated with an impact force is very small.
But what people have sort of fixated on when it comes to impact forces is the fact that they happen very rapidly.
So the rate of loading happens very quickly.
So you'll see the ground reaction force curve peak very rapidly.
If you put an accelerometer on somebody's shoe or foot you'll see a quick little spike in that acceleration when the foot hits the ground.
So that's what we refer to impact.
After impact after this, 50 milliseconds for the rest of the stance phase of running which you know, let's say 250 milliseconds or so.
That's when the big forces come.
That's when the actual motion of running, the up and down motion of the center of mass, that requires large muscle forces across the ankle and the knee and the hip.
That's when those musculoskeletal tissues are really, really being challenged.
And so, you know, to answer your question, is there good impact?
Is there bad impact?
What our research has shown, sort of time and time and consistently and I hope this doesn't spoil the whole interview is that impact forces really don't have a deleterious effect on the musculoskeletal system.
It's really the large loading magnitudes that happen after the foot hits the ground, where you're sort of arresting the center of mass.
Your muscles are contracting very highly.
And that's what we think is ultimately the stuff for lack of a better word the types of forces that are leading to injury.
For every study that you can find an association between impact force and injury risk.
I can find you another one that shows there's no association between impact force and overuse injury risk.
And I can find you another one that says the higher the impact force, the lower your injury risk.
And so while...
There's no doubt that running is a jarring activity where you have these very high impulsive loads that the musculoskeletal system experiences over and, over and, over and over again.
That can be damaging to the skeletal system.
But we no longer think that it's that little hit of the foot when you hit that ground within that first 50 milliseconds or so.
Great.
I think it's really helpful understanding the differences between that.
And I certainly remember, you know, maybe 15 years ago, after Christopher McDougall's book Born to Run came out and everyone was obsessed with barefoot running
There were a lot of these impact graphs floating around on the Internet because people were looking at the difference between you know very thick sold shoes and running barefoot and then shoes in between.
And it was like the two little impact peaks before the bigger loading phase of the gate cycle.
You know, I wonder, there are ways to diminish the initial impact.
And it sounds like it really doesn't matter too much whether you're having a high impact force right at the beginning of your foot strike.
But I'm curious about the loading phase afterward.
You know when you're really experiencing what we might call force, let's just call loading.
You know, when your body is kind of supporting itself on the stance leg, you are dealing with a lot of different forces on the body, from rotational all the way to trying to move your body over your center of mass.
While you can reduce the initial impact of a foot strike, can you really do much to offload the load of the stance phase?
Because that seems to me to be mostly dependent upon your body weight and the speed that you're running.
Yeah, you can do a lot.
But a lot of those things are going to be detrimental to your performance.
So there's things that have been used by military cadets for marching and running.
There's things recreational runners can do.
But Again, I'll preface this by saying it's going to likely impede your performance.
So what are those things that you can do to reduce the loads on the musculoskeletal system?
You can run slower.
Come on, brent.
Yeah uh, you can run at the same pace, but you can reduce your stride length so you can increase your cadence.
Um again, like i'm not necessarily sure that a coach is gone, you know, maybe coaches are playing around with cadence and things like that.
I just don't know how much room there is for manipulation.
When we get people in the labs and we do these studies, we get them to decrease their stride length by about 10, which is you can feel that as a runner, like it feels different than your natural stride length.
We played around with things what we call groucho running, which is like where you reduce the flight phase of the run and you kind of increase the amount of time that your foot is in contact with the ground for a given stride.
So there are things, especially that you can play around with what we call these spatio-temporal kinematics contact time, flight time, stride length, running speed.
These things can impact.
And so there are things, I think, that our runners can do, maybe when they're starting a new training regimen, Maybe if they're coming back from an injury.
Things that you can do to potentially minimize your chances of injury risk, with the understanding that it's not what you're going to be wanting to do when you compete.
Yeah, for the most part.
Many of those strategies strike me as counterproductive to most of the goals that runners have.
So, besides increasing your cadence, which is often a good thing to do if your cadence is too low, based on your easy running effort pace,
But for the most part I really only see maybe a five to 10 increase in cadence for some people, especially if it's in the 150s 150 steps per minute somewhere around there.
That strikes me as a little bit too much of that bounding stride where you're just spending a lot of time in that stance phase.
Okay, so for the most part it sounds like there's not too much we can do about the actual impact and load that we're experiencing as runners.
Now you spend a lot of time looking at how that repetitive loading process works, causes micro damage, accumulation and fatigue, soreness etc.
Now, we runners are unfortunately intimately aware of this process.
This is how we get our repetitive stress injuries.
What counteracts that habitual repetitive loading?
Like if we are constantly doing the same thing, and it is a jarring experience, as you say.
And we really can't get away from it.
It's part of the sport.
What are some things that is in the literature or in your experience can help counteract that experience?
Okay.
So first of all I'll tell you a little bit about what we do in my lab, in addition to the research that we do, where we get people into the lab and we do the motion analysis and we try to estimate the forces that the tendons experience, that the bones experience, and we look at playful interventions with cadence and stuff like that.
We do a lot of materials science with biological materials.
So we take pieces of bone, we take pieces of tendon and we subject these materials for lack of a better word to repetitive loading.
And we can manipulate how fast we load them.
We can manipulate how long we load them.
We can change the magnitude of the force that they experience.
And so one of the things that we find, remember, this is a piece of tissue outside of the body.
There's no remodeling taking place.
There's no adaptation to the load.
This is just treating this biological tissue as like an inert piece of material.
One of the things that we find with those studies is that the magnitude of the force that the tissue experiences plays a way more important role in damaging that tissue than the number of loading cycles.
Okay, so two loading cycles with a peak force of, I'm just going to say, 100 pounds or something like that okay,
Two loading cycles with a peak force of 100 pounds does not produce the same amount of damage as one loading cycle with a peak force of 200 pounds.
The one loading cycle that has 200 pounds, so twice the magnitude, is going to be way more damaging to that musculoskeletal tissue.
In fact, we have a rule of thumb when it comes to biological tissues.
If I can decrease the force that the tissue experiences by 10, I'll increase the number of loading cycles that material can experience 100-fold.
So just decreasing the magnitude of the load a little bit is really, really important for preventing the accumulation of damage and failure.
So I'm gonna get to your question.
But the first thing is like, what are things that you can do?
Well, what that means is like you shouldn't treat training intensity and training volume the same way.
The types of studies that we do in the lab suggests that if you decide to increase your running speed by 10, let's say that could have a much larger effect on your injury risk than increasing your running distance by 10.
In theory, it's much safer to increase the distance that you run than it is to increase the speed at which you're running or the intensity at which you're training.
So you know, I think that's interesting from the standpoint of are you looking to improve your running performance?
Are you looking to run further?
There's things that we know from material science that sort of are directly translational to you know people training that don't want to get injured.
The other question is like what are these other things that we can do to counteract it?
Well, I'm sure we'll get to this but like, rest is the best thing because when this tissue is inside the body, obviously the body has these natural defense mechanisms.
It has ways to repair the damage.
And then it also has, which is completely independent from repairing the damage that's there.
The body has this amazing ability to adapt to the loads that it experiences by increasing its shape, its size, improvements in its stiffness, structure and material properties.
And these kinds of things are really, really important for preventing the damage to occur in the first place, if that makes sense.
Yeah, I mean, I think this is an incredible insight that's really helpful for runners.
This one insight might be the price of admission for this episode.
Does this not mean that runners should be less cautious about volume and way more cautious about the overall pace of their running and the speed workouts that they're doing?
I'm putting on my coach's hat and trying to really actually be a bit prescriptive here.
It sounds like the the intensity of running is is typically what gets most runners hurt.
And so you know, in my mind, you know like, looking back on my entire running career, i was always a little bit more concerned about volume.
You know, let's not increase our volume too quickly.
You know, let's abide by the 10 rule.
And i never really thought about how running a workout too fast or going on an easy run but speeding up over the last three miles with my friends, because we're 23-year-old young guys at the time and we had the ability to do that, even though it might not have been the greatest idea.
So I think it lends a lot of weight to the idea that we should be very cautious with pacing and potentially a little bit more aggressive with volume.
The research suggests that that's the case, right?
Um, but no one's done the definitive study where you get the big group of runners and you force them to do these.
You know specific increases in intensity.
And there's another group that does the increases in volume and things like that.
There's been a couple of nice larger epidemiological size studies out of um from a Danish group um, that have done a series of these kind of running studies to look at running injuries.
Um, they've shown things like you know, too large of a change in um Not only training intensity but also training volume can increase your risk.
So I'm not trying to say that changing running volume isn't going to increase your risk.
But what I like to think of it, as it should in theory do it in a very linear manner where the loading magnitude's not going to.
So if you run 10 miles and there's a certain injury risk associated with that, And running 20 miles should basically double the risk associated with that.
And that's not the case for changes in loading magnitude.
This is highly, highly nonlinear where very small changes in loading intensity that you're going to get from increasing running speed will very quickly increase your risk of injury.
We need more of these kinds of studies that actually have runners undergo volume and intensity changes in a more methodical way to kind of tease out some of the effects of those training interventions.
I think that would be fascinating.
Yeah, it would be great.
Obviously...
Large-scale studies.
Hard to get the funding for those kinds of studies.
A lot of issues with dropout compliance.
A lot of issues.
I'm not an expert in this, but I know that people that study just – sports injury epidemiology like there's all types of arguments about what is an injury.
How do you define it?
Is it injuries, the thing that's diagnosed by the clinician?
Is the injury the thing that keeps the runner from running for more than a week?
Or is it pain associated with the injury?
So for sure we need those studies, but very, very hard to do, which is probably why they don't exist.
Yeah, yeah, I can dream.
Maybe we'll keep the what is an injury conversation to another episode.
That's probably a whole can of worms right there.
Yeah, that's not for me.
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You know Brent, one of the other things that I was thinking is the idea that if you can accurately track impact and loading of your body as you're training, you might be able to short circuit that nonlinear risk of injury.
Now I know you're working with the smart shoe company Avello on trying to figure out exactly how to do that.
Can you talk a little bit about you know how you're trying to figure out the type of impact and load that a runner is experiencing and tracking it over time so that, much like volume, you know, every runner pretty much keeps track of their mileage.
If we can track intensity from the perspective of impact or loading, I think we could hopefully reduce the injury risk among runners, which is unfortunately very, very high.
Yeah, I mean, I think the ability to track the load acting on the musculoskeletal system during any physical activity has a lot of potential.
Has a lot of potential.
So first of all, I'll start by saying that anything that you use right now, that's a wearable sensor.
It's simply a proxy device for the load that the musculoskeletal system experiences.
None of the sensors that are available on the market are able to tell you what the bone feels, what the tendon feels, et cetera.
So we're a little bit limited in the things that we can measure.
But a lot of these things that we can measure are fairly good proxies of the loads that the musculoskeletal tissues experience under.
I'm just going to say typical everyday running situations.
I'm not going to say that there is not some funky confounding relationship between what the sensors give us and what the tissue experiences.
Like there might be certain running grades, okay.
It might be that when you run up a hill, the relationships that you get with these sensors versus what the tissue is experiencing might be very different.
If you're running in deep, deep sand and things like that, you might have these weird nuanced relationships between what the sensor gives you.
But for the most part I think If you increase your speed, force goes up on the tissue and the force that you can measure with the wearable sensor hopefully goes up right.
And changes in cadence can be captured in this way.
And obviously, volume.
That's the easiest thing and probably the most accurate thing that you can measure with these wearable sensors.
So the work with Avelo is really fun because it's like my role there has really been working with them to develop the algorithms to appropriately interpret, like how changes in loading magnitude and changes in running volume are gonna impact the risk of injury.
And so we've got like a training load measure.
It's going to be weighted in such a way that high magnitude loads count more towards that measurement which Avelo is calling the impact score.
Not to be confused with impact forces, but the impact that it has on the body.
So yeah, I mean we're really developing algorithms that are fundamentally built on experiments that we perform in the lab, where we can directly quantify how loading magnitude impacts tissue damage, how loading volume impacts tissue damage, and we incorporate those into the loading metric, with the understanding that it's early days, but the more data that's collected on real runners using these algorithms, the better those algorithms will be able to be fine-tuned so that it works for actual runners.
Yeah, I think I'm really interested in this because it almost speaks to the idea of predicting an injury before it happens.
And as a formerly very injury-prone runner myself, this is the holy grail.
I have been searching for the answer to this question for my entire life.
You know, I am curious, from what you see on the lab, from any data from real-world runners using these kinds of sensors that Avello is using, are there any type of gait changes or aberrations in form or other signals that might indicate you know you're reaching this point of breakdown, of injury, of overreaching beyond your current abilities?
Is there anything that might give you a hint that that's on the horizon?
Again, it's a hard study to do.
I'll tell you what absolutely can be measured with these kinds of wearable sensors and changes in running pattern is there are ways that you can use these sensors to determine if somebody is moving in a way that's not their habitual movement pattern.
So you throw the sensor on them and you quantify, let's say, days or weeks of actual running, and then you can kind of Use these.
You know, you can monitor the sensor and you can figure out if somebody's got their own typical movement signature versus something that's not.
And you know you can also measure changes in these running metrics over the course of an exhaustive run, over the course of a marathon, etc.
And so there's lots of markers or lots of things that we can measure in the lab and outside of the lab that have to do with a runner fatiguing, experiencing neuromuscular fatigue.
Right. trying to equate those changes associated with fatigue to injury is actually a big problem.
First of all, I'm not aware of any research that suggests that running injuries happen when runners are fatigued.
So maybe it exists out there.
But the other thing is like what happens when people get fatigued is typically the loads acting on the musculoskeletal system decrease.
In fact, every single study we've done in the lab, where we've had a runner run to exhaustion, has ultimately resulted in lower forces acting on the musculoskeletal system.
Because if you run them on a treadmill and they can't change their speed when they start to get fatigued, what they start doing is they increase their cadence and the loads go down.
What happens when people are outside and they're not on a treadmill at a fixed speed?
When people are outside and they fatigue, what do they do?
They slow down.
So there's things that you can measure that are associated with neuromuscular fatigue.
I'm not necessarily sure that those are good markers of somebody getting injured.
Okay, so now are there biomechanics associated with somebody that's about to get injured?
This is my opinion after studying this stuff for decades and knowing enough about the literature that, like it really doesn't seem like there is one specific marker of injury risk.
There's no research to suggest it has anything to do with foot strike pattern or the shoes that you're wearing, or this or that.
What I subscribe to and what I think is really important.
Training volume, it's training intensity, but more important than that it's how quickly does somebody change their training intensity and training volume?
I really think it does come down to just training errors, for lack of a better word, these running injuries.
If you want to see a lot of running injuries, take somebody and put them in military.
Make them a military cadet, put them through basic training.
Like, I mean, that's when you really see big spikes in musculoskeletal.
You take people that are relatively you know they're not super fit, and then they're put into a demanding training regimen.
I do think that a lot of running-related injuries, certainly in university athletes, are happening towards the start of the semester.
They come back from summer.
They start training hard with their team again.
And so I do think that...
A lot of these running injuries happen because people are just not, their musculoskeletal tissues are not conditioned to accept the new loads that they're seeing, if that makes sense.
Yeah, totally.
And training errors, I think, is the right phrase for that.
Just mistakes that you make with your training.
My college coach would say avoid the three twos too much, too soon, too fast, which is basically a very quick and easy memorable way of saying progress gradually and really keep going the load of intensity and volume in mind.
One of the things that I'm interested in is the idea that when you get tired, your form starts to change.
I wonder if there's a case to be made, if by this idea that when you are tired, you are probably not moving in your body's preferred method or style,
Your gait pattern is a little bit changed.
If you continue on in that highly fatigued state with that inefficient movement pattern, the pattern that your body is not actually used to, is that a potential injury risk?
Because you might be experiencing lower loads at that time, but you're also not kind of absorbing the load in your body's preferred way.
It could be.
I mean, I think that's the...
That was probably the initial argument impetus for people to start studying, people in a fatigued state.
This idea that well your, your form kind of falls apart and um, maybe you're running in such a way where you're, you know, you're exposing tissues to loads that they haven't really seen before, and and and things like that.
And so in theory, it makes perfect sense.
All I can say is that when we get people in the lab and we fatigue them and we quantify the loads that are acting on these tissues, they're always decreasing with neuromuscular fatigue.
So... it could be something that we haven't looked at.
Yeah, another thing that we need another study to look at.
Well, let me ask you about surfaces that runners run on.
And this is something that I used to spend a lot of time thinking about.
My entire college track team would always try to run on softer surfaces because it was less jarring on our body, less impact that we were experiencing.
Does this actually matter?
Because I've also read science that says your body sort of compensates for the surface that you're running on by having a stiffer leg.
So you might actually experience very similar impact forces running on grass or running on concrete.
First of all, the surface changes the biomechanics.
It changes the impact.
Uh, it changes um, the muscular activity that crosses the joints and we can talk about why.
So you talk about like um, how your body will i forget the exact words that you use, but this idea that your body kind of compensates for the surface that you're running on there's, there's truth to that and the science shows that time and time again.
When you run let's say you're running at a fixed speed your body has sort of this again, this sort of natural up and down motion of the center of mass.
And you can actually get somebody to run across the lab.
And then without them really even knowing it, you can sort of change the surface.
And the first time that leg hits the ground, they modulate the stiffness of their leg right away so that the center of mass essentially takes the same path, or a very similar path.
So...
What that means is, when you run on stiff surfaces, you tend to have a more compliant leg or you tend to decrease the stiffness of your lower extremity joints, if you will.
That's when you're running on harder surfaces.
When you're running on softer surfaces, you stiffen up a little bit.
So for sure, the surface impacts the biomechanics.
The question about whether or not now the surface impacts injury risk is like, who knows?
Study's never been done.
And again, very hard study to do.
I'm just gonna assume that if we're talking small ranges in stiffness maybe hard grass and concrete and and things like that where the where the differences in stiffness or that not are not that much, i would be surprised if differences in surfaces had an impact.
What i don't know is, like again, what happens if you uh, just all you do is run in deep sand like i i, i really don't know what would happen um, So it's a good question.
Yeah, I think.
I think we were a little bit misplaced back in the day for constantly searching out soft surfaces because they were soft.
I still actually do this to this day, but for a different reason.
I mean, two reasons.
One, I just think it's more fun and that's just separate.
But number two, it's a little bit more variable.
Whereas if I'm running a concrete sidewalk, it is arguably the most uniform smooth surface that runners can experience.
And it's also the hardest surface, which I don't really care about too much, but it's more the uniformity of it.
Whereas if I'm on a trail, I'm every foot strike is a little bit different.
So I like it from that perspective, from injury prevention.
Just you know, reducing the repetitive stress of running, reducing the repetitive motion of every single foot strike.
You know, especially if you're running a lot of miles.
I think this can be a helpful strategy.
I.
I'm also curious about kind of like the relationship of impact on bone health.
This is something that a lot of runners will know that if you increase your mileage and your intensity too quickly, you're going to increase your risk of a bone stress injury.
My question is about rest days.
So let's say you take a rest day once a week.
My understanding is that bones adapt and model and change very slowly.
Does a single rest day actually have much of a relationship to keeping your bones healthy if you're experiencing a lot of impact on the other days?
Not from a damaging perspective.
Probably not from a repairing the damage that you'd incurred perspective.
But when it comes to strengthening that tissue, to begin with making the bone more dense and thicker, right
These things that physical activity can help with, that rest is sort of incredibly important.
So you're right.
Like one day of rest.
It doesn't do a lot by allowing all of a sudden, your body's going to be able to repair all this damage that has incurred.
Although cumulatively, who knows, right?
Because one day a week over the course of 52 weeks, that's 52 days.
And that's better than zero days.
But when it does come to bone, what we know is that the cells inside bone that sense mechanical loading.
Okay, we have dedicated cells inside the bone.
They're called osteocytes.
They're the ones that sense mechanical strain and in turn orchestrate a cellular response to sort of build new bone and make it stronger.
Rest is incredibly important in that process.
Um, because those, those cells tend to get saturated very, very quickly.
They need rest to sort of recover their shape and their sensing ability.
So it's kind of funny.
Actually, running is not like the best thing exercise you can do to strengthen your bones.
If you want the best exercise you can do to strengthen your bones, become an Olympic weightlifter.
Like what do you do?
You go there, you lift insanely high magnitude weights in a hugely impulsive manner, right?
You You do like a clean and jerk or something like that.
And so it's high magnitude, rapid loading, very dynamic.
And then what do you do?
You go and you sit down on a chair and you recover.
Your bone loves that, because now, when you do that loading again, the cells are in the perfect state to be able to sense that mechanical load.
When you go out for a run, The osteogenic benefits osteogenic that means like the bone building benefits that you get from a run they're gonna happen towards the beginning part of that run.
And then everything after that has diminishing returns, doesn't mean that there's no benefit to building bone at mile 5, at mile 10,
It just means that the benefit to building bone at mile 5 and 10 are way way way way, way less than they are for those first 100 cycles.
So when it comes to building bone, you don't need a lot of loading cycles, but you want high magnitude dynamic loading.
So that's what's important.
So again, not conducive for running performance.
But if you're building bone through running, the best way to do that would be to break that run up into several different bouts throughout the day.
So go and run a half a mile and then don't do anything for an hour and then run another half a mile, like that.
Your bone, your bone, would love that.
And so that's kind of the this acute rest, that rest in between loading bouts.
But the same thing holds true for building bone.
It would be much more beneficial for your bone to no, because now we're getting into this diminishing returns thing.
Rest is beneficial for bone adaptation.
I'll just leave it there.
Yeah, yeah.
I like the idea of taking a five-mile run and doing 10 by a half a mile with a three-hour recovery.
I think if I started prescribing that to my athletes, they'll know I've jumped the shark.
Yeah, no, it's not good for the athlete, but you know what it's good for?
A lot of bone building is hugely like.
The greatest amount of bone building that you could do happens during growth and development.
Um doesn't take a lot means that kids during growth and development they need um, they need a lot of uh.
High impact, dynamic loading, variable loading.
All this stuff is really good for bone building and they don't need a ton of it.
And at the same time, in theory, to preserve bone as an adult.
Again, I'm not talking about the competitive aspect.
But to preserve bone as an adult, you know, the 55-year-old post-menopausal woman doesn't need to be going out and running 10 miles in order to do that.
They can skip rope, they can do box jumps and it really only takes a little bit to be really important.
Well, you just hinted to something that I was going to ask about, which was plyometrics.
Can you talk about the role of plyometrics in bone health?
Because it does seem like it fits the requirements of low volume, but high impact force, high load.
Yeah, absolutely.
So those are going to be the most beneficial things to bone.
High magnitude, highly dynamic.
So if you're getting that through plyometrics, then yeah, that would be a good bone building exercise.
Yeah, I think one of the interesting things I'm learning about running is that it's just a less effective bone building type of exercise.
And a lot of runners have this idea, including me, up until a few years ago, that running was a great bone building activity.
Of course, it's not helping my upper body, but at least I have strong hips and leg bones.
But I'm glad I'm lifting weights and doing some high-impact things.
What about sprints?
It also seems like, rather than a distance runner taking their five-mile run and dividing it up into these really short bouts throughout the day, if you were a sprinter and you did a sprinter's workout of low-volume, high-intensity repetitions that are very high impact, it does seem like that would be better for your bones than distance running, but probably still not as good as plyometrics or heavy weightlifting.
Yeah, I don't know, but like I mean, the studies are out there, cross-sectional studies looking at the quality and the quantity of bone that a sprinter has versus a long-distance runner, and the sprinters have better bones.
They just do.
So, in addition to these mechanical things that we're talking about, where the cells become desensitized and the magnitudes aren't high enough and dynamic enough to promote bone and running,
I mean, the other thing that you have to think of is...
Before I get there, I want to make sure that nobody that's listening to this podcast thinks I'm out here saying that running is bad for your bones.
That is not what I'm trying to say.
In fact, there's research to show that people who run, at least recreationally, tend to have better bone health than sedentary controls.
There does seem to be a point though, where running too much can actually be detrimental to your bone health.
And it has nothing to do with these mechanical principles that we're talking about, and has everything to do with what I don't know a lot about, which is energy availability, and and nutrition.
And, and, and so that stuff is hugely important.
And when you're in a energy deficient state, as is the case with a lot of endurance athletes, because they just can't consume the calories that they're burning.
And then there's other reasons, of course, that it doesn't matter how much mechanical load you experience or what mechanical load you experience.
Your body is going to need calcium.
Where is it going to get that calcium?
It's going to get it from your bones.
It's going to start resorbing bones.
So there is a point where too much running becomes too much, but it's not the mechanics per se.
It's more... if you're not paying attention to the biology and the physiology of your body.
Yeah, the fueling side of things I think is just as important to bone health as the kind of the training side of it.
You know what you're doing.
To maintain bone health kind of has to come from your activities, but also from your nutrition as well.
Brent, I'd love to end with kind of a, well, I think it's a fun question.
I just would love to hear your general thoughts on the culture of super shoes in the running world.
These are those high stack, very squishy foam shoes.
Many of them have carbon plates in them.
I've done episodes talking about how they change your mechanics.
I'm just wondering about your perspective on how they change the distribution of load, how they change the impact forces of that first foot strike.
Any thoughts on that phenomenon in the running world and how it might impact potential injury rates moving forward,
Yeah, I have some opinions on this and thoughts on this.
And we're doing research in this area right now.
So...
There's certain things that we have not been able to find with our research so far.
So there was some case series, studies that came out in literature that kind of suggested that these shoes may be increasing stress, fractures of the foot,
And then when we do studies in the lab and we look at the loads that are acting on the foot and specifically we quantify the strain or the deformation that the bone is experiencing in these shoes, we have not been able to show a detrimental effect of these shoes on loads of the foot.
You mentioned something that's interesting, load distribution.
There's no doubt that that is happening in these shoes.
You know, the work at the metatarsal phalangeal joint sort of decreases, and then you can see sort of increased mechanical work at other joints of the lower extremity, particularly more proximally as you go towards the hip and things like that.
So these shoes do change your biomechanics subtly.
It's not like a crazy big change. but they do change them.
Does that mean that they're gonna increase the risk of somebody getting injured at another joint or something?
Are runners gonna start seeing injuries at locations that were not as prone to injury before these shoes were used?
I think that remains to be seen.
I think it's going to take some time.
But I do think we're going to start to see studies coming out that – because I think now there's been enough time.
You can't go to a single race without seeing people in these super shoes.
So I think we're going to start seeing a lot more research to sort of – to see if, if these shoes are changing the location of injury.
But like, something to think about, something to consider is like, just because somebody gets injured in the shoe doesn't necessarily mean that it's the shoe per se, right?
Like, maybe what the shoe does is allow somebody to maintain a faster pace for a longer period of time.
And as a consequence, the musculoskeletal tissue is experiencing higher loads.
So...
You know, there could be other explanations.
If we do see the changes in injury rates, there could be other explanations besides the shoe.
It could be the performance gains that you get from the shoe that are actually what's causing the injury, if that makes sense, rather than some kind of biomechanical alteration.
You know, and then I think a lot of people get excited when they buy these shoes because And they go out and they run a lot, or they buy them because they're training for something.
And then they're more prone or more likely to make a training error.
I know, whenever I get a new piece of gear for anything that I do, I'm like really want to go out and I want to try it.
And so the easy answer is no.
I don't think there's any good evidence out there right now that these super shoes are causing more injuries, but only time will tell.
Yeah, I tend to think that they're simply a little bit different and different type of shoe, just like a different surface, just like a different speed or volume that you're used to.
It can all have somewhat of an effect on your, your injury risk, and it also kind of depends on how everything else in your training is is fitting together.
You know, from a stress perspective, from the other types of of loading and impact that you have in your training, whether you're doing some strength training, whether you're progressing intelligently, like it all fits together.
And this is just yet another variable that runners have to consider.
Well Brent, I know I put you on the spot by asking a lot of loaded questions and you're not a coach or a practitioner.
You're in the lab and it was a little difficult, but I just really loved hearing your thoughts on things and I know we weren't going to solve the injury crisis among runners today in this conversation, but hopefully we gave a few people a little bit of a better understanding of some of these ideas so they can better apply it to their training.
Is there anything that you wanted to add that maybe we didn't get to, that was related or similar to the topics we discussed that our listeners might be interested in?
No, nothing that really comes to my mind right now.
But thanks.
I really enjoyed it.
I really enjoyed it.
Yeah, yeah.
No, thanks again.
And if anybody wants to follow along with your work, find you online, is that possible for them?
Oh, yeah.
Just email me.
They can find me.
Google me.
Brent Edwards, University of Calgary.
And yeah, happy to have discussions.
Well, thank you so much for that.
I will put some of that info in the description so folks can find it easily.
Brent, thank you so much.
Thanks, Jason.
Those reviews are incredibly impactful and helpful for this small business.
If you have questions about your running, feel free to email me at support at strengthrunningcom, or you can search our website at strengthrunningcom.
For more digestible tips, videos, memes, and more, follow me on Instagram at jasonfits1.
We'll be in touch.
