Monday, 30 May 2011

Born to Run? - Part 2

Long overdue I'm afraid - but I've been a busy chap (update to follow).
So here it is, the long awaited, "Born to run" part 2...
Hope you enjoy - please share with your friends if you find it of interest!

In “Born to run” Part 1 I spoke about some of the “prime movers” involved in the action of running, but I spoke little about the  running  gait and, most importantly I think, the foot strike.
This is something I have spent a great deal of time analysing in my own running and, as a result, trying to change.
There are those who would say that you run the way that is most natural to you – it’s personal. In other words, there is no “right way to run”.
Well, I guess that’s true to a point.
However, the same could be said of swimming. There is no “right way to swim” either. If all you want to do is get from one end of the pool to the other then, by all means, jump in, thrash your arms and legs about, and with a bit of luck you’ll get there - eventually.
People my age will no doubt have memories of the inefficient frenzy of “swimming” at the end of the great kids TV show “We are the Champions”!  Trashing about, having fun, doing what came naturally, but far from efficient as a means of getting from one floating pontoon to another!

However, if you want to get to the end as quickly and efficiently as possible, then few would dispute that there is, most certainly, a particular way to swim that is far quicker than any other. It’s called the front crawl, or free style. It’s a “technique” that has been developed to optimise the speed and efficiency of a human through the water.
Crucially, it’s a technique that must be taught. It’s not something you’d ever likely stumble upon just by doing “what feels right”.
Look at kids as they learn to swim. The “natural stroke” might be something closer to the doggy paddle. But, to my knowledge, there have been no speed records set using that technique!
It’s the same with many other sports so why should running be any different?
If all you want to do is get from A to B – by all means, run how you want. But if your goal is speed and efficiency, then there must surely be a way or “technique” of running, which is superior to others for this purpose.
I think there is, and that’s what I want to discuss today.
Starting with the basics, running speed is related to two key biomechanical variables. These are: “cadence” or leg speed and “stride length” or how far you travel with each stride. So to run faster you simply move your legs more quickly, or you aim to travel further with each step (or both). Simple!
We can despatch with the first one pretty quickly. Interestingly, research and analysis of elite runners has shown that leg speed or cadence, is pretty consistent. It seems to fall within a very tight range irrespective of race distance (discounting sprint events). So for race distances from 800m right up to the marathon, an optimum cadence seems to be around 85 – 95 strides per minute. Women tend to be a little higher than men and long legged athletes tend to have slightly lower cadence than those with shorter legs – stands to reason really. But all are remarkably similar.
However, for a number of reasons, most amateur and club runners will have a much lower cadence and would no doubt find 85-95 strides per minute pretty hard work! This can be improved through certain types of session (speed work, intervals, track etc) which will bring about muscular adaptations allowing them to “fire” more quickly. Distance runners will tend to have a greater percentage of “slow twitch” muscle fibres to “fast twitch” ones. There’s little you can do about that. But certain training methods can train your natural slow twitch fibres to behave more like fast twitch ones.
However, your cadence may well be limited by the actual biomechanics of your running style or “gait”.
The key culprit here is the heel strike. Landing on the heel with a straight leg is an alarmingly common way of running. It’s how I’ve always run (until recently) – it is most akin to the action of walking and so feels quite “natural”. People walk, people start to jog, people run – it’s a logical, natural progression and few people actually get coached on correct running technique. So it’s easy to understand why there are lots of heel strikers out there.
Additionally, modern trainers with thick cushioned soles “allow” runners to heel strike without excessive discomfort, but the forces are still there and those forces are being directed in completely the wrong direction for efficient forward motion (and doing a lot of damage and causing fatigue into the bargain!)
In other words, running with a heel strike is like running with the brakes on. It will be incredibly difficult to increase your cadence into the high 80’s and beyond when you slam the brakes on with every foot strike! The photo of me below from 15 or so years ago, shows my extreme heel strike. Take a look and try to visualise where all the impact forces will go at the moment my heel hits the ground!

Heel striking - back in the day!

It’s interesting to note that before the advent of thick cushioned running shoes, runners tended not to heel strike. Running in plimsolls would have made this technique very uncomfortable. Try it for yourself. Run down the road in just your socks. I take a bet you quickly move onto the fore foot to “protect” yourself from the impact. It’s also interesting to note that before the advent of thick cushioned running shoes, runners tended not to get injured!!
So what about stride length?  Well this is where it does get a little tricky as most people, in an attempt to increase stride length, will end up reducing cadence. This is because most people confuse “stride length” with “stride reach”. These are not the same thing. Increasing stride length is not achieved by simply striding further or trying to move your feet further apart from one and other between each stride.
Think of the some of the early paintings of horses in “full flight”. Most were misguidedly depicted with legs as far apart as possible, because painters felt that for horses to travel such great distances with each stride, then this is surely what they must be doing.

Horses defying gravity!

It took a photographer called Eadweard Muybridge to settle it in 1877 with his famous series of high speed photographs which show the horse’s legs bent rather than straight at the precise moment in time when the horse was fully airborne.

Muybridge's famous highspeed photos of a horse galloping

It should be the same with running. At that glorious moment of full flight, the lead leg should bent, foot below knee, as illustrated here by the great Haile Gebrselassie.

Haile in "full flight"

Attempting to “stride further” is often accomplished by straightening the lead leg, heel striking and landing with the leg out in front of the body. Running becomes more of a “lollop”. Cadence drops and so does efficiency. It’s viscous circle.
So how do we increase stride length without simply trying to take bigger steps?
Well, simply put, you need to become more “dynamic”. Strangely, to start working on increasing stride length or “air time” you need to start by reducing how far you “reach” with your lead leg. In other words, to consciously shorten your “stride reach”. Do this and straight away you will detect an increase in cadence.
Let’s break it down.
You’ll remember from my previous blog that hip flexors are crucial. They drive the lead leg forward. But stop! Don’t now straighten the leg and let it swing forward like a pendulum! Instead, keep the knee soft and the foot high. This reduces the effective length of the “lever” from hip to foot and allows the hip flexor to move the limb quickly forward (remember cadence!). Now, maintaining a slightly bent knee, bring the foot down so it lands vertically below or slightly behind the knee – but NEVER in front. The knee should still be bent.
Land on the fore foot, maintaining a bent knee. In this position, the ground reaction force is driving you forward, not backward as with a heel strike. Don’t try to deliberately point the foot in an attempt to land on the toes. The “ball” of the foot is really where you want to land, most likely to the outside edge.
As previously mentioned, the best way to experience this, is to simply remove your shoes and run (grass is probably best – to avoid cutting your feet). You should find that you naturally move to the balls of you feet.
Running barefoot is not something I personally plan to do full time (although plenty do!). I do however try to do one “barefoot” session per week throughout the summer. This will often be tacked onto the end of a grass speed session and may include some strides and technique work. I find that the sensation or “proprioception” of my feet / limbs remains once I return to running in trainers. It’s also a great way of building foot strength (more on that later).
So, back to the running cycle. Having landed on the forefoot, as your centre of mass moves over your foot, your heel drops to the ground and your knee bends a little more. Don’t for one minute imagine that fore foot running is about bouncing along on your toes! It isn’t and that would be a very quick route to Achilles or calf strain. Few people run on their toes only (sprinters mainly). The heel should drop to the ground after the initial fore foot landing. At this point, amongst others the Gastrocnemious and Soleus muscles (calves), Achilles tendons and soft tissues all begin to stretch. Imagine this is like pulling back the strings of a bow. This not only gradually decelerates the ground reaction force, it also “stores” the energy. As the cycle continues this energy is “released” like a spring and, combined with force from the muscles, propels the body forward.
This “elastic energy” is a critical yet, so often, overlooked part of the running action.
This is a very important point...Running is as much about elastic energy as it is about muscular force.
At this point I want to deviate briefly and talk about stretching. It has been a long held belief that stretching is beneficial to athletes as it can increase range of motion (ROM) and reduce injury risk. In actual fact, there is little evidence to support any reduced injury risk and while stretching does certainly increase ROM, one does have to question whether this is to the athlete’s advantage. Referring to my previous statement about elastic energy, it should be clear to see that an athlete able to hyper “dorsiflex” their foot (pull their toes up) for example, will be less able to build elastic energy in the calf and Achilles. It seems that the best advice is to stretch up to and only slightly beyond the range of motion required of your sport – but don’t take things to the extreme. There is for example, little point in a runner being able to do the box splits, but this would be essential for somebody practicing martial arts which involves high kicking etc. Excessive flexibility can lead to instability and loss of dynamic “elastic” energy. More than simply “stretched” it is far better for the muscles and soft tissues to be well warmed up prior to exercise, for this reason, dynamic stretches (involving movement) are preferable.
Loads on the internet – but here are some that I use..

So, back on we’ve hopefully realised, landing with a heel strike makes it almost impossible to build high amounts of elastic energy into the lower leg.
Another killer of elastic energy are trainers with thick heels. Let’s say you’ve landed nicely on your forefoot.  The heel drops but actually, because the heel of the shoe is so thick, it contacts the ground before any elastic energy has been stored in the lower leg. This is like pulling back the string of our imaginary bow in a broom cupboard!  We can’t pull the bow back very far, so there is now less energy stored in the bow and the arrow won’t fly as far.
So this brings me onto what I think are the most important aspects of trainer design.
Thick soles are bad because, they not only prevent correct foot (heel) motion but, more often than not, they lead to instability. Shoe manufactures compensate for this instability by adding all sorts of complicated motion control features. These features improve stability but provide too much mechanical support for the foot.
The foot doesn’t need motion control – it’s already a highly evolved piece of structural engineering design! Over a quarter of the bones in the human body are in your feet!
Think of expensive trainers as “plaster casts” for your feet and you are not far off the mark. Yes they provide support and control but, by doing so, over time, the foot becomes weaker. In the same way that muscles in a leg will atrophy (waste away) when a plaster cast is worn for a few months.
Using shoes that provide minimal support and control means the bones, muscles and ligaments of the foot all have to work hard (as intended). In the long term you will gain strong, stable, injury proof feet! Not cosseted, weakened, injury prone ones!! It’s interesting to note that the prevalence of foot injuries such as plantar fasciitis seems to positively track the increasing complexity of running shoes when by rights they should be reducing!
As an interesting aside here, most runners preserve their “racing flats” for, well, racing! Stands to reason I suppose. But these same runners probably do the bulk of their running in over supportive training shoes. Their feet become “accustomed” to this level of support, chronically weakened and when they move into racing flats for competition, expose themselves to injury risk.
Me? All my running is now done in minimal shoes (Saucony Type A4). They provide my feet with minimal support and allow them to move naturally and become strong. I am now comfortably running marathons is minimal shoes – (the heel of the type A4 is only 13mm thick and, crucially, the fore foot 9mm giving a minimal difference between the two)

My new best friend - The Saucony Grid Type A4 - All I ever run in

Orthotics are another very contentious subject. Podiatrists are often quick to prescribe supportive foot wear or orthotics to athletes with disorders of the foot and lower leg. However, these disorders can often (but not always) be the result of chronic weakening of the foot through years of inactivity in over supportive footwear. Orthotics provide yet more support and the cycle continues. Now please, those of you who wear orthotics, don’t throw them away quoting “but Duncan said so!!” I am no expert and there are many athletes with genuine biomechanical problems which orthotics “may” be able to correct. However, if you currently don’t use orthotics – but are thinking about it, why not try a few bare foot grass sessions first in an effort to build some strength back into your feet.  Those using orthotics might like to do the same once a week, but any changes should be implemented slowly  and assessed regularly.
My feeling with regard to footwear is to keep it simple, and build strong feet.

But thick soles are great because they absorb shock right?
Well let’s get one thing clear...
You can’t destroy (or create) “energy”. You can merely turn it from one state to another. This is the law of conservation of energy. 
Light bulbs for example turn electrical energy into light and heat energy.
So the notion of a running shoe “absorbing” energy is just not correct.
All that energy has gotta go somewhere, and even if a shoe could “absorb” energy why would you want it to? Isn’t that a bit of a waste? You want to take that energy, store it, and release it in a way that propels you forward.
Think of a car suspension system. The tyres can be thought of as your trainers and the shock absorbers as your legs, (bones, muscles and connective tissue).
The car tyres provide a degree of comfort and protect you, the occupant, from the harshness of the road. However, they do little dissipate road shock. That’s the job of the suspension system.
A car with big squashy tires, but no suspension would be almost un-drivable (this is like heel striking in thick trainers). Conversely, a car with a good suspension and very minimal tyres handles like a dream! (this is like forefoot striking with minimal trainers).
So when we run we have to deal with large impact forces as we land with our full bodyweight on one leg. If we land on our heel with a straight leg the only way of slowing this impact force is with the compression of the shoe’s foam / rubber sole (and the cartilage in our joints!!). Now even the most space age materials are just not able to deal with the magnitude of forces involved here.  Those forces simply travel up the straight leg, through the ankle, knee and into the hip (and neither of these joints are particularly well known for their shock absorbing properties!)
Now let’s imagine landing on the ball of the foot with a slightly bent leg. The forces are the same, but this time they can be decelerated by the bending of the knee / ankle and the resistance and stretching of long muscles and tendons of the entire leg.
The bottom line is... damaging forces on the body (hips and knees particularly) are greatly reduced when landing on the forefoot.  And a forefoot gait is promoted and optimised by running in minimal training shoes or bare feet.
Ground reaction forces are most damaging when landing on the heel with a straight leg and this is the gait promoted or at least facilitated by thick soled (heeled) running shoes.

So yes, contentious as this may sound. Forces on the body are more damaging in thicker soled shoes than those with thin soles (providing you run with a fore foot strike).

Equally - I would question the universally accepted view that we must bin our trainers after a few 100 miles, because they "loose their shock absorbing properties"!


Humans have been running in bare feet, leather sandles, canvas plimsoles, even bits of old car tyre without injury for 100's of years, so how can a 200 mile old pair of trainers be damaging?? - They are if you continue to heel strike!  
As a final point – I would suggest anybody can benefit from looking at their running gait, but don’t imagine this is something you can change overnight (and nor should you aim to). Not only do you have to build specific strength in muscles and soft tissues that you might not currently be using, but you also have to overcome the deep routed “hard wiring” in your brain that is telling you “how to run”.
Anybody that has been running for some time doesn’t need to “think” about it, as Nike would say you “just do it”. But in making the change to forefoot running, you will have to go through that learning process again. You will literally have to think about every step you take. You will also find yourself slipping back into your “old ways” particularly as you get tired, but this is where you really need to concentrate and persevere!
You will need to reduce your run mileage dramatically. Start with a few miles – your feet, calves and Achilles will ache! Allow them to adapt and grow stronger. Build up the length of your runs slowly and only progress once you feel no pain in the new muscles and tissues that you will be recruiting.
I think it took me 6 months to build the sufficient, specific strength required for fore foot running in minimal shoes and about a similar length of time again to break the hard wiring in my brain!
I now class myself as a “natural fore foot runner”.
It’s been hard work – but worth it.
At the age of 39 I think I’m running faster than ever!!

Finally a natural Fore foot striker!