In this blog, I try to steer clear of the hype and offer real answers to questions, or the best answer available given the existing knowledge base. But sometimes things come along that I can’t resist.
If you are in this video, or you look like one of their crew, I promise we can help you.
Yesterday’s post got lots of comments; I’d like to post a bit more here to help folks understand this concept a bit deeper. Why does this idea about balance matter at all to runners? Midstance is basically single leg standing balance. However there is a difference between “reactive balance” and “proprioceptive control.”
Let’s define a few terms here:
Strength – relates to the cross-sectional area of a given tissue. This is related to the muscle’s ability to generate force. Bigger muscle, bigger force. Simple.
Proprioception: there are 3 primary things we use for balance.
Note- you do have other reflexes that play a role here, but these are the primary ones that have the greatest effect.
If these 3 systems “agree” then you are using your body as best you can to achieve control in stance. So let’s look at examples of how these can change. If you are on a merry go round, your eyes see you are spinning, your somatosensory feels the body turning, and your vestibular system says you are spinning. Everything is fine. If you stop, your eyes and somatosensory system say you have stopped, but your inner ear fluid is still swirling – signals don’t agree….. and you become dizzy.
So why is it harder to close your eyes in single leg balance? Most folks are visual dominant. They rely highly on their eyes to find their position in space. The problem with this is that it’s “slow.” You need to see information, process it in the visual part of your brain, then send a signal to the part of your brain that control motion (motor cortex) to make a correction. Somatosensory information is very very fast. There is a direct relay between the sensory and motor reflexes both inside and outside the brain – resulting in fast rapid “micro-corrections” of position. Let’s use an example.
If you look at skiers, surfers, skateboarders, white water paddlers – they all have something in common – they need to make positional corrections VERY quickly – faster than they can see visually and adjust. They get good feedback about the position of their body from their hard ski edge (transferred up through a very stiff plastic boot), or the rail of the surf board (transferred through their bare feet). Each and every time they practice their sport they are refining their position sense by “feeling” where the body is. They consistently train and improve their somatosensory system.
Research shows that the somatosensory system is highly trainable. Its best done frequently in small doses. Instead of trying to balance on one leg for 10 min each night, its better to do it 20x’s a day for 30 seconds. Yes, you CAN improve your balance….by practicing. Not your “I’m-rocking-back-and-forth-like-a-weeble-wobble” re-active balance, but your “proactive balance.” Proactive balance means “I know what to do to keep my body stable – I can micro-correct to improve my stability.” Think about spreading your toes out wide to maximize the width of your foot. Try to push your big toe down – not curling, just down as you keep it straight. This will improve your muscles firing inside your foot. I’ll make a deal with you – if you work on your single leg balance every day, you’ll find not only will you be able to stand with eyes closed, but also be able to begin to rotate left and right with your eyes closed. The goal is to reduce your dominance on vision and improve your use and perception of “feel.” It works!
OK – so let’s now look at this with respect to running. I’m going somewhere with this I promise – I’m building a case for you. There is a ton of research that supports the idea that firm surfaces offer better “feel” to the individual and thus better balance control. Soft surfaces mute the feedback to the person and result in poor stability in stance. The goal is to maximize your level of active stability control that your body can produce.
If I am in the clinic working with a patient, I always work them in barefoot, and will use all kinds of rocker/wobble/rolling boards to do this. All of these are FIRM and HARD surfaces. Even though the foot is moving, the contact between the ground and the foot is solid. The person gets good feel for what is happening. I am not a proponent of foam pads to work on balance. Why? Foam pads let you cheat and roll off to the outside of the foot. They don’t mandate that you activate the big toe. They don’t train “pro-active control.”
Let’s take this idea and now apply is to footwear and the entire rationale for you reading this post. What is traditional footwear? – It’s got an elevated heel, a wider lever arm than your foot, and a big marshmellow stuck underneath. This marshmallow allows your weight to shift to the outside of the foot. The heel-higher-than-the-forefoot provides a “rocker” in front of the shoe that you can simply roll off of. It lets you “cheat” by conforming to your foot. A lot of runners have gotten used to this. Their feet have become weaker as the shoe does more of the work.
When we look at minimal footwear or barefoot running, this foam pad is gone completely or reduced significantly. Suddenly, you can’t cheat. You have to actively use the muscles inside the foot to stabilize. The absence or reduced cushioning in the shoe allows you to get better “feel” – why do so many proponents of barefoot and minimalist running claim that they feel “free” or like they’ve “been released”…….? It’s simple – your foot gets more information from the surface you are on when you don’t have a big piece of compressible foam in the between. More information = better muscle activation.
I see a hand up in the audience.
Q: So I’ve been running for years and I still can’t stabilize with my eyes closed. What gives?
A: closing eyes might be slightly overkill, but you know what? – Almost every standardized assessment for balance testing has an eyes-closed component to assess just what we mentioned above (the 3 things that impact proprioception). So if you have good balance with eyes closed, I know that you are good in this regard and not going to ask you to add this into your training program. It allows the examiner to differentiate how well you use different skills that affect balance. If the eyes closed part is the issue, and this is connected to faulty foot and ankle mechanics during running, it give me more information as to what your limiters are as a runner.
Q: So I’ve been running for years, and I still can’t stand on one leg – even with my eyes open. What gives?
A: There is no research to show that your poor balance will result in injury, but there is research to show that those with a number of lower extremity injuries do have poor balance. Further, I’ll be happy to say that those with poor single leg balance almost always have some very interesting finding in our lab – they usually have altered forces around the ankles which results in abnormal stresses to the lower leg and foot. Improving your single leg balance is a way work on prevention. I’d much rather you not get hurt and keep enjoying your runs, than not. Maybe you are one of the lucky ones who has run for years without injury – awesome! However, research shows that 82% of you runners will be hurt at some point. Both personally and professionally, I’d rather see you in the 18% of those who are not.
Let’s say you are out for a night on the town. Your significant other turns to you and says how do you like my outfit? Unless you answer this question perfectly (still not sure how to answer this even after many years of marriage!) you may notice that your significant other withdraws for a while to cool off. Could be a few minutes, could be for the night, but this time away allows things to mellow and return to a state of bliss yet again. What does this have to do with shoes?
It’s common practice for a lot of runners to have multiple pairs of shoes at one time. This though process behind this has been that running in a shoe breaks down the cushioning properties of the shoe, and it takes time for it to rebound before your next run.
Well, Let’s look at some objective information on this subject. This is not going to turn into a discussion of minimal shoes vs. traditional construction. We are simply going to look at what happens to the properties of the midsole itself. The midsole is the squishy part of the shoe that lies between your foot and the tread. Its commonly made of a chemical compound called ethyl-vinyl acetate (EVA). Shoe manufacturers manipulate properties of the midsole to get their shoe to perform a certain way. Obviously a minimal shoe has less of this midsole material in it then a traditionally constructed shoe, but they both have some type of cushioning material between the foot and the shoe tread.
As you run, you are applying mechanical forces to the shoe itself. These forces physically break down the midsole. In fact, lets look at this at the microscopic level. The following picture is from a study (1) that looked at the state of the midsole at various points in the shoe’s lifespan. In fig A, you are looking at an electron micrograph cross section of a brand new shoe. It’s easy to see the outline of the well defined air pockets in the midsole. This intact formation allows the midsole to perform as it was designed. Fig B shows a cross section of the midsole after 500 kilometers (310 mi). This type of magnification allows you to see that the edges of the former well defined air pockets are now frayed and weakened. Finally, Fig C shows the midsole after 750 Kilometers (466 mi). It is now possible to see that the majority of the air pores are frayed, and in fact some of them have actually deformed enough to create holes. Thus, the structural properties of this midsole material are now very different from what they originally were when new. While your body can repair tissues that have been affected from mechanical stresses in running, your shoes cannot. Resting your shoes by the front door between runs won’t reverse these changes.
While it’s probably a good thing to be nice to your shoes (running in wet environments with no chance to dry out may accelerate breakdown of the midsole), they don’t have feelings. You can pound on them day in and day out – even 2 runs in the same day. The breakdown of the material in your shoe is cumulative. So what happens to our gait as shoes breakdown?
A 2009 article (2) revealed that running in worn shoes caused the runner to increase their stance time (time spent on the leg) and alter their lower leg range of motion in order to keep forces on the body somewhat constant. What does this mean? As your shoes break down, the body will slightly alter its gait style adapt to the gradual changes that occur in the shoe itself. When do these gait alterations reach critical mass (causing injury if you don’t buy new shoes)? Shoe breakdown is variable depending on the runner’s mass, running surfaces, and gait style. I know runners who note that they become injured if they put more than 250 miles on their shoes, and I know runners that put well over 1200 miles on a single pair. The old school rule of thumb states 400-500 miles, and is likely a good starting point based on the research stated above.
Happy Running!
Yesterday we briefly discussed the idea of loading rate, and why it matters to you as a runner. Today we’ll talk of the 3 primary ways runners can change loading rate, and likely dispel some myths while doing so. If I ruffle some feathers while doing this, don’t get frustrated. Its good to stretch you brain. Let’s look at what we do know about loading rate, and what is a bit fuzzy.
Methods to decrease loading rate involve a combination of:
****Warning – some of this gets a bit tedious, but there has been a lot of request for this information lately, so lets dive in shall we?
Let’s get right to the hot topic. Should you land on you forefoot, midfoot, or rearfoot?
Right below, is a graph of a runner landing with a midfoot gait. You’ll notice a very distinct impact peak (first bump) and a larger active peak (second bump). You’ll also notice that the slope of the first bump (from the x-axis to the top of the first bump) is quite steep.
What kind of foot contact pattern made this graph? Nope – not a heel striker – but a midfoot striker. In fact this woman is about as midfoot as possible – her foot came down completely flat down at contact. I know ….this runs counter to a lot you’ve been told right? Hold on – let’s keep going.
Now look at runner #2’s graph. Notice the single mountain (or peak). Notice that the slope of the line from contact to peak is quite less steep than that of Runner #1. A LOWER loading rate! Guess what kind of contact style this runner utilized? A heel-strike. Yes. You read that right. A heel striker had a lower loading rate than a midfoot striker …..in this situation.
What gives? The media tries to make things simple. They say that “mid-foot” or “forefoot” is better than rearfoot. I love reading running forums where people with way too much time on their hands armchair quarterback running styles. They look at a picture or video of a contact pattern of some guy running across the screen and say “wow – nice midfoot strike –that runner is efficient.” They don’t know who the runner is, or what his time was for the race. They just saw a foot strike and proclaimed him efficient. Then they’ll scroll down and see some picture or video of some guy heel striking and proclaim that he/she is an “in-efficient” runner based on the heel strike. This “in-efficient” runner might be an in-efficient runner. Or it might be Meb Keflezighi (a runner who is just a bit faster and more efficient and than most of your reading this post). You see, these arm chair-quarterbacks aren’t very good at identifying efficient gait. Fancy force plates are. I do this for a living and still need data from my lab to give me the answer because no one can actually see forces. So what have we learned from these fancy force plates? Its NOT rear-foot or midfoot or forefoot that matters – its where the foot contacts in relation to the body’s center of mass.
As I stated above, I picked some outliers just to make a point. It is true that for MOST runners, adopting a midfoot or forefoot gait style will lead to decreased loading rates. However, its not because the foot lands differently, its because a rear-foot style typically allows you to land with the foot farther in front of the body’s center of mass (over-striding). Switching to a contact style that moves the foot closer to the body’s center of mass usually means that we land closer to the font of the foot. But not always. Let’s look at the elite runners to dig a bit deeper.
To run really fast, it’s very simple. You either increase your stride rate or your stride length. Simple right?
So let’s summarize what we’ve said about contact foot contact style. For most runners, landing closer to the body’s center of mass is an effective tool to lower loading rates. Barefoot running, minimalist running, and increasing cadence (faster cadence means you don’t have time for your foot to reach out far in front of the body) are all effective tools to accomplish the end goal of decreasing loading rate. This being said, contact style is NOT the only way to decrease loading rate. Its possible to have lower loading rates with multiple foot contact styles, and other factors as well.
***Note: Unless the person is accelerating, it is not possible to have the foot contact directly under the center of mass. At steady state, the foot does (and should) contact in front of the center of mass.
The effect of posture
We said that, in general, a foot contact closer to the center of mass would decrease loading rate. On the flipside, posture can be utilized to alter the center of mass in relation to the foot. Most of us stand, walk, run, etc with poor posture. Take a look at the runner below. The runner is in exactly the same phase of gait, except for a more arched low back on the right than on the left. The posture on the right is typical to most runners. We hang out in the “back seat” with lots of arch in the low back. This change in lumbar position moves our center of mass backwards thus causing our foot to land further in front of the center of mass. Therefore, keeping a neutral lumbar spine (not arched) is essential to keep our center of mass over our foot when running – and has the effect of minimizing loading rate.
Lastly – gait cueing and limb stiffness. Here’s where things come together, but also show need for additional research. In our lab, when we get someone with high loading rates, we show them their ground reaction force plots in real-time as they run, and ask them to change it. Normally, we don’t tell them how, we ask them to “play” with their graph shape as they run. Most runners figure out how to minimize their loading rates by getting visual cues, or feedback. This is the best way since the runner is aware of the conscious modifications they are doing to alter their loading rates and can see instant feedback to observe success – thus learning! If they don’t “get it”, we guide them through the technique modification so they can see the effects of their form changes as they run. Again – the goal is to get the runner to retain this sensation so they can alter their gait to make long-term changes to decrease tissue stress. On the simpler side, research has been done that simply told runners to “run soft”. These individuals were found to decrease their loading rates. Gait cueing works. How does it work? People modify their contact style, posture, and their limb stiffness to achieve a desired result. Limb stiffness relates to how compliant the runner maintains the knee to modulate the rise and fall of the center of mass. There is more work to be done here to dig deeper, but this should hopefully answer the bulk of questions for now.
Summary:
What does this mean for you as a runner?
There is mounting evidence that minimizing loading rate has vast implications for a number of injury prevention strategies. There is also mounting work to show links to performance, though this is inconclusive at this time. There is additional work to be done to show how the gait style changes observed with decreased loading rate correspond to improved performance. Another topic for another day……
If you want to try to decrease your loading rate, you need to get your foot to land closer to the body. Barefoot running is a good drill for this since it “forces” you to avoid over-striding. There is evidence that a properly constructed minimal shoe should also lead to minimal loading rates (although no one can say all minimal shoes since the definition of this market sector is so vague). Keep your torso centered over your lower body and avoid the temptation to run in the “back seat”, especially as you fatigue.
Run Tall! Run Soft!
Yup…. Less (loading rate) = More.
So you went to the “insert giant athletic store here”, and the 16 yr old kid who works part time for the summer, who is the “expert” on running watches you for about 30 seconds, and decides to tell you that you in fact, pronate. Or worse…..maybe you even over-pronate. Never fear though, they say! They’ll just go in the back and grab some of those big mutha shoes to totally stop you from pronating and be your personal savior.
Before you plunk down your hard earned cash, we should probably come to terms with a few things.
What is pronation?1 – First, let’s re-cap what this pronation stuff is all about. Pronation is not bad; in fact, it’s the body’s natural shock absorption mechanism. When the foot moves into pronation, it becomes like a loose bag of bones. Everyone pronates to some extent. Some more than others. If you didn’t pronate, you’d have problems with- you guessed it- shock absorption. The opposite of pronation is supination. In supination the bones of the foot become more congruent (increased contact between the surfaces of the joints). This increased contact produces a rigid lever for push off in gait. So we should land in a supinated position, and move to a more pronated position during stance to decrease shock, and then move to a supinated position to achieve a rigid lever for push off.
Let’s re-cap this again using America’s favorite national pastime, Tetris. When the pieces fall from the top of the screen, we can move them about and rotate them freely. They can move. This is how the 26 bones in your foot function in the shock absorption or pronation phase. They should move about to dissipate force. Now imagine those same Tetris pieces once you’ve placed them in the stack. They can’t move right? They become congruent and are locked in place. This is similar to the foot when you are in supination.
2- Now that we understand pronation as something that is not really bad; let’s talk about when it occurs. As evidenced in a study carried out in our lab and published in the Journal of Orthopedic and Sports Physical Therapy, maximum pronation of the foot occurs after the heel has left the ground. Why does this matter? Remember that 16 yr old kid? He’s going to grab a shoe off the rack that is a motion control shoe –designed or should I say marketed, to stop pronation. A shoe like this features a higher density material on the inside of the shoe. The claim is that this different density material acts to stop the pronation from taking place, thus fixing your issues. If you’d like to see if your shoe has this, just look at the inner side of the midsole (marsh mellow stuff between the fabric upper and tread). If some of the inside of the shoe is a darker color than the rest, it’s likely a “dual density midsole design”.
OK – so let’s get back to timing of pronation. Shoe companies put this increased density material to “stop the foot from pronating”. Well, we found out that maximum pronation occurs after the heel is off of the ground. So guess what? – All that higher density material in the shoe isn’t even touching the ground to try and stop the foot from moving at the time when the foot is moving the most! Hmmmmm……makes you think doesn’t it?
3- We know what pronation is, and when it occurs, and now we should address the question of stopping pronation. Pronation is necessary. I’ll even say in the right amounts and at the right time, its good. I’ve seen PLENTY of runners who have problems because they don’t pronate enough. However, stopping pronation isn’t really in our best interests. It’s better to learn to stabilize the amount of pronation. The thing is that no shoe can do this- you need to learn to use the muscles in the foot and the muscles in the hip to stabilize the rotational motion that naturally occurs in your legs. Can you do this? How good are you at stabilizing your pronation? A visit to the SPEED Clinic can help you pin point your issues and fix them for good.
Parting thought –please don’t read this and think that we are saying that shoes don’t make a difference. They do. The objective research we do combined with our clinical experience has proven to us that they make a huge difference. We view footwear as part of an intervention to help you perform at your best. Shoes are very different. How much of a shoe you need, or weather you even need a shoe at all (barefoot running anyone?) are all part of a comprehensive assessment here at the University of Virginia.
When most runners, coaches, running shops think of the single biggest problem that affects runners- the answer usually points to the most feared word in running – “over-pronation.” However, we told Amby Burfoot (link here) that our years of experience quantifying running mechanics through the use of 3D gait analysis has shown us otherwise.
While it’s true that some of us out there may pronate more than others, it isn’t exactly what we’d call an epidemic problem in America. We’ll estimate that less than 30% of runners truly over-pronate (excess motion in the foot) their feet while running. To find the real answer, we need to move up eyes up and look at the hips. About 80-90% of runners don’t extend their hips.
What is hip extension anyway?
Lifting one knee up to the chest moves the hip into flexion. If you extend the hip the opposite direction (past vertical) that is hip extension. The goal is to do this without extending your back. Stretching your hip flexors to get more motion is the key
So why don’t most runners extend their hips?
We tend to sit. A lot. We sit in class. We sit at work. We sit in our cars. Cyclists, you spend all your time on the bike sitting in hip flexion. When we continually sit in hip flexion, the hip flexor muscles become tight. So tight that the overwhelming majority of runners can’t extend the hips. “Now wait a minute” – you might say –“I see all my friends and their leg does get behind them when they run – so they must be extending their hip right?”
Tight hip flexor muscles cause you to get your leg behind you not from extending your hip – but by arching your lower back. This can cause injury since an arched lumbar spine compromises our ability to use core muscles while we run. This sets us up for a host of leg injuries and also is the most common cause of low back pain in runners. Further, lack of hip extension compromises your running efficiency. As we increase speed, the bulk of the work supplied to the legs need to come from the hips. Well, if you can’t extend the hips, you are missing out on critical force to move your body forward.
So how do I get hip extension and is it really that simple?
You’ve got improve your range of motion of the hip, and your ability to control the new motion. The best hip stretch is a kneeling hip flexor stretch. Beware though, a lot of the videos on-line show incorrect form for this stretch and you don’t actually wind up extending your hip flexors at all (they stretch the quads). Check out the July 2010 issue of Runner’s World for an article we helped them put together. It shows correct technique to stretch the hips, and some simple exercises to learn to use your new range of motion.
You can run quarters on the track in 80 seconds. Maybe you can even do them in 60 seconds. Maybe you hit a PR for sustained power on the bike. You can drive your golf ball 250 yards down the fairway. Does this mean you are really performing at your potential?
Every time we practice a movement, we are reinforcing a particular movement in our brain. This is commonly referred to as “muscle memory”. Training technique is an often overlooked aspect in endurance world. Each joint in your body has an axis around which it moves, with muscles controlling the movement. These tissues are engineered to move a specific way. If we learn good muscle memory, we continually re-enforce good habits – and come competition day – we perform at our potential.
Competition to you might be a round of golf with friends on Sunday or qualifying for the 10,000 meter at the Olympics. At every level, focusing on your form can improve your performance. Our body and mind strive to get the job done – at all costs. Often, this can mean we learn an incorrect strategy to get the job done. And even if your form is better than most, we all suffer form alterations when we fatigue. When these form changes occur, we have a decrease in efficiency. Since we are performing “different” than we normally do, we put more strain through our body’s tissues and are more likely to become injured. Understanding the stages of motor learning will shed some light on why we need to work on our form in the first place:
Unconscious Incompetence – this means we have no idea that we are doing something with incorrect form. Most of us fall in this category. Look at the picture of the woman landing from a jump. The joints of the lower body are designed so that the knee tracks over the second toe when we land from a jump. The goal is to preserve proper alignment when we move. This athlete has no idea that her knees crashing to the inside are a problem. She doesn’t know that it significantly increases her risk for an ACL tear, patellofemoral syndrome, hip impingement, or a host of other issues. She doesn’t know that this landing technique will hurt her running, jumping, and cutting performance.
Conscious Competence – The athlete understands that there was an issue, knows correct technique, and now is able to perform correctly without thinking about it. She has removed the stresses from a flawed technique, and can perform correctly in sports-specific drills and in competition. The is the stage we want to be at! Think about some of the best performances you’ve ever done. What were you thinking about? Most successful athletes can’t even remember what they were focusing on. They were in “the zone” and just let their bodies perform using the skills they learned through a lot of practice.In our quest to improve, we often focus on adding intensity or training volume thinking it to be the magic fix to take us to the next level. We’ve often heard the phrase “train smarter, not harder.” Adding time and focus to alter your technique pays off in spades. So let’s expand that saying to “move smarter, not harder”. The focus of the biomechanical analysis done in the SPEED Clinic @ the UVA Center for Endurance Sport is identify your unique compensations and make those muscles smarter!
Jay Dicharry's Website, An Athlete's Body 