Tag Archives: shoes

My new book: bedtime story for the new royal baby?

It seems the Brits have been busy. A few weeks ago, a new Royal baby greeted the world, and it seems my collection of bedtime stories to Prince George was released just in time!

photo-14Anatomy for Runners has made quite an impact. Since its release almost one year ago, its been one of the top selling running books, and achieved significant accolades with runners, coaches, clinicians, and the industry. In fact the book has done so well, that it was picked up by a UK-based Lotus Publishing Group. The overseas edition, re-titled “Run Like an Athlete” is available now to anyone on the other side of the pond. I’m quite happy with this title – its actually hat I wanted to call the US book in the first place. It features all the same excellent content, although its been translated from English to well, English……

Yes…..The Queen’s prose is quite different from our countrymen’s linguistics. Going through the editing process with the publisher, I’m shocked at how much it was altered for the european audience: “Soccer mom = football mum” are among thousands of edits.

Note: this version of the book is best utilized with hot tea, crumpets, ascots, and a Hugh Grant movie playing in the background. 

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my copy arrives by none other than the Royal Mail

The running shoe industry has been taken by storm: TP Striders

Revolution, not evolution.  The latest innovation for your feet is not from the behemoth with swoosh. Its not from the company who brought you “those funny toe shoes.” Instead, this latest venture was announced last night on prime time television.

Its innovative “dual-purpose outsole” has a unique feature to help you out of a certain situation that always seems to come on about 1 mile into your run. Run prepared! If you’d like learn more, check out the video below.

Running Footwear: A critical look at what we know about footwear and how to select the best fit for your athlete

The media likes to spin things to make headlines. I’m not too big on spinning, I’d rather just help educate. If you’d like to clear the air and see what we know, what we don’t know, and what’s been spun, you can check out this webinar I’m doing for USA Track and Field next week on Mar 26th. Coaches will get CEU’s from their couch.

The make of running shoes have historically gone from one side (thin and flexible) to the other (stiff and bulky) and are now moving toward the middle of the road. Which is best? And how do you match running shoes to an individual runner? In this webinar presentation, Jay Dicharry will comb through relevant research and clinical experience to help you approach your running retailer with the knowledge of selecting the right tool for the job. Learn how to ensure that you are running in your shoes rather than your shoes running you! By the end of this webinar you’ll be able to understand:

  •                 the evolution of footwear
  •                 how footwear has been classically prescribed
  •                 proof that this fit model is ineffective
  •                 how shoes impact your running form
  •                 how barefoot running impacts your form
  •                 how shoe wear impacts your form
  •                 how to select shoes for you
  •                 what minimal shoes are, and if you are ready to make the transition

Chevy Tahoe or a Mini Cooper? A tip on running shoe selection.

You are about to leave your house and have the keys to both your cars in your hand. Which do you take?

Today, you have to drive through town town to get some groceries, and then to the mall. Its a slow drive on neighborhood streets to the freeway. Your SUV is comfortable, affords a good view of the road, and has lots of room for the stuff you are going to buy. Given the fact that SUV’s account for huge number of sales in the US, the public agrees this is a logical choice.

OK – its the weekend. You are going to flee the city and head up to the cabin. Its a really twisty backcountry mountain road. Turn after turn, its hard to even maintain the posted speed limit. Do you select the SUV that ensures you need to slow down due to body roll, or do you take the sports car? The sports car is lighter, lower, and has a firmer suspension. It was designed for these very conditions. While a stiffer suspension may be less comfortable driving through the burbs, the improved “road feel” you get with the sports car helps you drive better at speed through more challenging roads.

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Time to go shoe shopping! You ask the salesman to pull two pairs of shoes for you. The first feels like a cloud at first step. It feels like you could stand around in them for hours. Your quick run test on the sidewalk in front the shop confirms that same cushy marshmallow feel during your run. Going back inside, you slip on shoe #2. It feels comfortable, but is much firmer. It didn’t grab you at first step as you walked around the store, but when you repeated your short demo run outside, it felt pretty much like the shoe wasn’t even there. The firmer feel felt a bit more responsive.

What running shoe should you buy?

Well, the marketing research is clear. People buy shoes b/c of 1) color, and 2) “first feel”. First feel is that first step you take. You know that sense of walking on a cloud…..the same feeling that made you think you could stand around in them for hours? Well, that doesn’t have anything to do with running shoe selection. Running is not standing. When you stand, you have half your body weight split between each foot. The total load on each each leg is about half your body weight. When you walk, sometimes you have two feet on the ground, and sometimes you have one foot down on the ground. So at the most, you’d have your full body weight on one leg, and at the least, it would be split between both legs. And when you are walking, your feet are on the ground for a long time. If you need to “micro-correct” your muscles to stabilize your body, you’ve got time to do so.

Running isn’t standing. And its not walking. During running, your foot is only on the ground for a very short time: The average runner moving at 7.2 mph is on the ground for only .17 seconds. Decisions on stability need to happen very very quickly, faster than you can actually think about them. And when running, there is no double leg contact. You are either sailing through the air, or in contact with a single leg. That single leg must not only support your full body weight, but about 2.5x’s your body weight.

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So what “car” do you pick? Well, lets look at hundreds of research articles on foot and ankle balance. Almost every single article says that you have a harder time balancing and stabilizing when on a cushioned surface. On marshmallow-cushy surfaces, the muscles that control your foot and ankle kick on too late and not enough to keep things under control. So if you are going to rally around a twisty mountain mountain road, the stiffer suspension on the Mini Cooper gives you better traction and feel. When running, a firmer feeling shoe provides a stiffer surface for the muscles in your foot and ankle to support your body. Said very simply: the foot works better when on a firmer surface.

So do yourself a favor. Go to the store. Try on your shoes. Obviously you’ll stand, and then walk outside or over to the treadmill. But resist the urge to make an impression on the shoe until you are actually running. Of course you should buy a pair that feels comfortable! But most of us are in shoes too soft and squishy to be running fast. Pick the right car for your drive, and the right shoe for your run. Running comfort, not walking comfort, should be key.

South by SouthWest Festival: When Biomechanics Attack

Check out the report WIRED magazine did of my talk with ESPN writer Henry Abbott at SXSW music festival. Likely the only time I’ll get to say I presented at the same conference as Al Gore, Bruce Springsteen, Seth MacFarlane, Jay-Z, and Jeffery Tambor (unfortunately not on the same stage at the same time!)

Nice summary, except they didn’t really get one critical point across. You CAN improve your hip flexibility and your hip strength!

Check out the WIRED article here and check out this link I did for Runner’s World a while ago on improving hip mobility

 

When the Big Man in Red calls, you have to be ready

Thought I’d share this with you guys, because it’s a bit different than most of the cases I see here in the lab on a daily basis. So the phone rang on today. The caller ID just said “North Pole” – not knowing what to expect, I picked up and surprisingly spoke to Ms Claus! She spoke very frantically. Santa was overheard in the background, and did not sound jolly. One of their athletes was down for the count less than one week before the big day, and they were in serious need of our services. ASAP. Rudolph is suffering from Achilles pain, and can’t fly at race pace. At his current speeds, they’ll be about 8.5 hrs behind Christmas-Eve night delivery schedule. Kids on all sides of the world should all be able to wake up to their loot. Running late is not an option.

Seems like all this global warming has taken its toll on a number of fronts. Yes, its hotter, and more of you are driving Prius’s (or is that Priui???), and sea level is rising – but folks, reality is now staring you in the face…. and its taking your Christmas presents with it. Typically, the reindeer wind up their training volume when the snow starts to fall in the end of October. This year, October saw record high temperatures. Instead of training, the reindeer were sunning themselves at the lake. A typical week in October looks like this:

  • Sunday: light 6 hr hike through the woods
  • Monday: 8-mile Hill repeats (about 4,000 ft per climb) x 12 reps
  • Tuesday: AM Speed work: 10 x 1.5 miles, all negative split. PM workout: easy 5-mile flight
  • Wednesday: Flight training: Circumnavigation of Arctic circle x 3. 1st and 3rd easy, middle rep at tempo pace.
  • Thursday: Weighted sled training: 3.5 metric tons for 6 miles, 2.5 tons for 4 miles, 1.5 miles for 2 miles at 90% VO2
  • Friday: easy run to Canada and back, with 1 hr of fartlek
  • Saturday: Tempo intensity, all flight – equator and back. Goal time is around 2 hrs.

The Elves in the training room had to be pulled out to help with some last minute Xbox orders, and they are understaffed. So Donner and Blitzen volunteered to get Rudolph down here within 2.5 hours The made it in 2:10. For starters, Rudolph is super nice – a bit too much on the Type-A sometimes, but I guess its that kind of work mentality that gets you to lead the sleigh year after year. He said this is the first time he has been injured. He even did weekly jogs sans horseshoes in the early summer after reading “Born to Run”, but he thought it was the sudden ramp up in volume that really got him.

Head Elf stretches Rudolph after last week

So, we did what we normally do. Got some markers on Rudolph and threw him on the treadmill. Results? Well, Rudolph has some serious imbalances going on. Pretty weak stabilization of his right rear ankle, and some inflammation of his bursae seem to be the culprit here. But the real issue was his weak right hip. Failure to drive off with his hip was actually increasing the stress on the achilles. Using data on our force-measuring treadmill, we cued him to use more of his glutes to stabilize his hip. We fit him for some minimal horseshoes to reduce the lever arm on his ankle. Lastly, we gave him some self-mobilizations he could do on the rooftops to keep him supple throughout the night. So how’d it go? Well, here’s hoping that all of you have something special under the tree on Christmas morning…..on time. Happy Holidaze!!!!

Proprio-what? a deeper look at balance and stability

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.

  1. Vestibular  (inner ear) – If you are standing still, inner fluid is still. If you turn your head suddenly, the inner ear fluid swirls and this information goes to your brain to help determine acceleration and change in position.
  2. Somatosensory – You “feel” the ground. You have sensory receptors in your skin which allow you to feel something – light and deep pressure, vibration, heat, cold, etc. This sensation goes a long way to improve your tactile feedback to help you remain stable.
  3. Vision – We use our eyes to orient our head and trunk and let us know which way is “up”.

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.

Less From Your Shoes, More From Your Feet

There has been a lot of interest lately in the transition to minimal footwear. Am I going to get hurt? How long does this transition take? Is this really better for me? Will my old shoes take it personally? Last year at this time, there were 6 minimal shoes on the market. This year there are 64. It’s a hot market, and folks are taking notice. While shoes are nice to talk about, let’s not forget that it’s the runner in the shoe that plays an active role in this equation. Shoes don’t run by themselves!

The recent article by Giuliani et. al. has raised some concerns.2 They highlight 2 cases of stress fractures in 2 different runners who transition to minimal footwear. The switch to minimal footwear can be dramatic. You get more “feel” since the squishy midsole is reduced or gone. You get a lower differential from your rear foot to your forefoot. These 2 factors change a) the position of the foot (Heel isn’t higher than the forefoot in full contact) and, b) the demand of the runner to stabilize the foot inside the shoe. In short, with less “stuff” in between you and the ground, you need your body to do a bit more, and get accommodate to a bit more as well.

Ever hear about the experiment with pre-K kids with the cookies? They put a kid in a room with cookie on the table and tell him/her that they can eat the cookie and they’ll get one cookie. BUT, if they don’t eat the cookie, they’ll get 2 cookies later (yea!). The tester walks out of the room and the kids go into panic mode when sitting in front of this stellar, delicious cookie. Most eat the single cookie for instant gratification.  They fail to see the merits of waiting patiently for a better result.

What in the world do cookies have to do with running shoes? A lot. The switch to minimal footwear can pay off in the long run, but you need ensure you’ve got what it takes for a successful transition. Obviously any time you make a change to your body, there is an adaptation period that needs to occur.  A lot of “experts” say that it will take 6 months to a year to fully transition to a minimal shoe. I’d like to think that this is overly cautious, and like to discuss why using the anatomy. We’ve found great success using the following 3 criteria for runners looking to run with “less”.

1. Mobility: Traditional running shoes have about a 10-13mm drop from the heel to the forefoot. This creates a “rocker” effect in the shoe. Take a look at a shoe from the side and you’ll see that the curve from the ball of the foot to the tip of the toe rises up. Since your foot is flat, you need to ensure that you have enough mobility (called dorsiflexion) of the big toe to allow the foot to roll over. Additionally, since the heel is higher in a traditional running shoe (think a small high heel) the heel chords are used to operating in a shortened position. You need to ensure that you’ve got the mobility needed to allow the heel chords to operate form their slightly lengthened position. So what to you test?

    • Ankle mobility (heel chords) – you need to be able to dorsiflex (cock the foot up towards the shin) about 25 degrees. Lack of mobility here means you’ll need to stretch the calf and Achilles.
    • Plantar facsia mobility – with the ankle in about 5 degrees of dorsiflexion, you need to have 30 degrees of dorsiflexion at the big toe. If you don’t have this, you can’t roll over the toes, and will be forced to spin off of the forefoot.

2. Single-leg Standing Balance: normal balance has been identified as standing on single leg for 30 seconds
with a still upper body and full foot contact. Since the midstance phase of running is essentially a single leg squat, it is essential that the runner is able to maintain the foot in contact. A triangle between the inside ball of the foot (1st MTP), end of the big toe (distal phalanx of the 1st ray), and outside ball of the foot (5th MTP) should be seen. When in single leg stance, the muscles in the foot need to be “pro-active” not “re-active”. If you are wobbling your foot back and forth when standing on one foot, you’ve got some room to improve your “proprioception” – or sense of where and what you’re your foot is doing during contact. The most successful way to improve single leg balance is to perform it frequently (15-20 times a day) for small doses (30 seconds each).

3. Ability to isolate the Flexor Hallucis Brevis: a key factor that distinguishes humans from primates is our medial longitudinal arch. This arch is actively stabilized by the flexor hallicus brevius (FHB). While standing, try to drive the big toe (1st MTP) into the ground (plantar flexion) while slightly elevating (dorsiflexing) the lesser toes. Make sure not to roll the ankle in or out. This test enables screening of muscles inside the foot that stabilize the arch. The FHB can be easily distinguished from the longus (FHL), as the FHL crosses another joint in your big toe (1st IP joint), resulting in your big toe curling. Spend some time getting to know your foot. Aim to drive the big toe down while lifting the little toes (without curling the big toe!), and lift the big toe up while driving the little toes down. It’s the best way to work on coordination of muscles that actively stabilize the foot in stance. It’s your foot – control it! If you can do this, it’s a sign that you can keep the rear foot stable on the forefoot when the body sees the greatest amount of pronation (which is just slightly after midstance and AFTER the heel is off of the ground by the way.)1 Midstance is when forces are highest throughout the body- about 2.5x’s your body weight. You need the internal strength to be able to respond to these forces to keep things in alignment.

When your foot “works” it can actively stabilize the transfer of forces through the foot. If you don’t pass these 3 tests, no worry  -get to work on improving your limitations. Pay a visit to your local PT if you need help with specific exercises and stretches to improve.  If you lack mobility, research shows it takes 10-12 weeks to gain significant improvements. So stretching for 2 weeks likely won’t be enough for most folks. Improving tissue length can take some time. If your limitations are in the balance aspect, you’ll be amazed how quickly this improves if you simply practice practice practice. Typically, about 2 weeks yields a significant improvement. Finally, strength gains take about 6-8 weeks to achieve. So if you really have trouble isolating your foot muscles, this could take a bit to get them stronger – but you can always improve the strength of your muscles!  Passing these 3 tests doesn’t mean that you should go run a marathon in your new minimal shoes on day 1, but we’ve seen that folks who master these have little to no problem making the transition. I’ll note here that these tests are not new in my mind. I’d like all runners  – even those who run in traditional shoes – to pass these tests. Its that when the “stuff” under your foot is less, these traits are that much more important.

So invest some time to improve your foot – Because it’s always better to have 2 cookies instead of one!  Shoes make a difference, but it’s the runner in the shoe that you’ve got control over.

References:

Dicharry, JM., Franz, JR., Della Croce, U., Wilder, RP., O’Riley, P., Kerrigan, DC. Differences in Static and Dynamic Measures in Evaluation of Talonavicular Mobility in Gait. J Orthop Sport Phys Ther 2009;39(8):628-634

Giuliani J, Masini B, Alitz C, Owens BD. Barefoot-simulating Footwear Associated With Metatarsal Stress Injury in 2 Runners. Orthopedics. 2011 Jul 7;34(7)

Do shoes have feelings ?

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!

  1. Verdejo, R. , Mills NJ. Heel-shoe interactions and the durability of EVA foam running-shoe midsoles. J Biomech. 2004. Sept; 37(9):1379-86.
  2. Kong, PW., Candelaria, NG., Smith, DR. Running in new and worn shoes: a comparison of three types of cushioning footwear. Br J Sports Med 2009 43: 745-749

Loading Rate: Part 2: Forefoot, midfoot, rearfoot……..Who cares?

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:

  1. A foot contact style closer to the body’s center of mass
  2. Minimizing excessive lumbar extension (which shifts the body’s center of mass posterior in relation to foot contact)
  3. Changing limb stiffness through feedback training.

****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?

  • Stride rate- this is also referred to as cadence. Cadence ranges in cycling are pretty variable. Cyclists use anywhere from 45 – 140 rpm in competition, depending on the event and terrain. When we look at running, you’ll notice that cadence for middle distance through marathon distance typically ranges from 88-96 rpm. This is a much narrower effective window than cycling. We’ll look more in depth at cadence in a later post, but for right now, its safe to say at the elite level, there isn’t a huge difference in cadence values.
  • Stride length –if cadence values are held fairly consistent, the only other way to run faster is to adopt a longer stride length. The stride length of someone running 4:30 miles is significantly longer than running 7:45 miles. What we see is that a number of the elites land on the rearfoot, but their center of mass is still very high up at the time of contact. When running, you are a projectile in the air with your center of mass following a parabolic curve. So even though the elites often “contact” on their rearfoot, they don’t really have much pressure (force) on it until their center of mass lowers to the ground.  This effect produces a low loading rate with a heel contact, and is exactly what occurred in runner #2 above.

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.