Wednesday, 21 December 2011

Natural Running, Biomechanics & the Problems with "Typical" Running Shoes

Over the past 6 months or so I’ve done a fair bit of reading into the current state of thinking with running shoes and the science behind it, but it is a really subjective topic…. Even some of the keenest promoters of “less is better” on your feet are including a fair dose of caution when it comes to encouraging people to think away from the traditional cushioned, stability controlled (ie anti pronation) trainer that has risen to dominate the market in the last 30-40 years.
My opinion (and it may still be proved wrong, there’s the cautious tone raising it’s head already!)  is that we shouldn’t really be running in heavily cushioned shoes with anti-pronation features and highly elevated heels. BUT for the vast majority of everyday runners this how they have learnt to run and it is engrained in them now. Hence why the majority of recreational runners runner with their heels hitting the ground first (more on why this situation has arisen below..)  If you are one of the lucky few who already run on their mid/fore foot, congratulations, go buy yourself a pair of more minimal shoe and enjoy (in a gradual manner…). However for the rest of us, all is not lost. 
It is widely recognised that running is a learnt skill, dominated by control from our brains. In many animals running is a low level response controlled from the spinal column and hence can be considered an almost automatic response, but humans have more control over things! We can adjust/adapt our running style to improve our ability. This article on the Science of Running blog is very good and goes into detail about how our bio mechanics work and  gives advice on how to change your running to maximise the body’s bio-mechanical ability.
 So we can change and improve things, but (and this is the big BUT) you have to do it carefully! Ditching your old shoes and going straight into unfamiliar shoes with features designed to promote good bio-mechanics is risky. Injuries can develop as a result of muscles/tendons etc.. suddenly being subjected to new forces and stresses without a gradually introduction to the new demands. A good example of this is the achilles tendon, the elevated heels of modern shoes (not just running shoes) have caused the Achilles to be under- used and become weakened in a lot of cases. Go into minimal shoes and the loading on the Achilles shoots up, but this is a good thing, as the Achilles functions as an important energy storage and release mechanism during the running cycle (ie we want lots of force in it!). The downside is that if your Achilles is not strong enough, the switch of shoes could lead to damage. The key point is that any switch of shoe type to try more minimal shoes should be done gradually and in conjunction with your current shoe type. I made this mistake in the summer with a new pair of neutral low heel light weight Saucony Kinvara shoes. I ran them a couple of times (quite fast longish runs) and tweaked an ankle tendon. This seems to be because the shoe has no pronation control I was running off road quite a bit and hence subjecting my ankle to lots of lateral forces. There was nothing to stop my ankle from going inwards more that it should. At the next cross country race I did (in my normal race shoes) the ankle tendon got severely exacerbated and I ended up not running for a week (and another week to get back to normal). As a side note, it turns out that my ankle pronation issue may well stem from an imbalance in my hips (twisted pelvis) which has been treated by an Osteopath, I’m waiting to see how the ankle responses now I’m back doing some runs in the Saucony’s. Importantly, the ankle problem probably doesn’t originate from using the wrong type of shoe, but it appeared to! The Kinvara’s are amazing comfortable and light shoes to run in (if slightly narrow at the toes) and the low heel, means it feels more natural with a fore or mid foot style, but I definitely feel the lack of heel if I switch back to heel first running, it becomes very hard on my heels (as I can feel the impact normally hidden by the heel cushion of regular shoes)
A quick shoe 101, the typical recreational running shoe that has dominated the market for the past 30 odd years is characterised by the following features; large different in the height of the heel compared to the toes, typically in region of 12mm, and effectively elevates the heel; considerable cushioning in the sole of the shoe; pronation control features that are designed to correct the lower leg alignment. I thoroughly recommend you read this article (again from the Science of Running site, by Steve Magness) on the fallacy of these features (particularly cushioning and pronation control). I have borrow some of the ideas from this piece and others in writing this. Basically shoes have become highly protective and are almost ‘proscribed’ these days, as if they are medical devices!
Bio mechanically we are designed to run with a fore/mid/whole foot strike, but not really with a heel strike, unfortunately, no-one realised this when the recreational running boom started in the 70’s and as the masses shifted from walking to jogging to running, they did so on their heels. This wasn’t very comfortable in the thin heeled, unsupportive, zero cushioned shoes of the day, so the shoe companies started to develop thicker shock absorbing heel counters to reduce the impact. This actually had the reverse effect on impact force, as as the cushioning got more and more, it increasingly reduced the sensory feedback from the feet, which made runners land with heavier feet (as they were unable to feel the true impact with the ground). Put it this way, if you can feel that the ground is hard and unforgiving, you will tend to walk/run with lighter feet to reduce the discomfort, heavily cushioned shoes remove this sensory feedback.
That’s just for the cushioning aspect of ‘traditional’ running shoes, the same goes broadly for pronation correction, in fact some argue that over pronation (the tendency for you ankle to dip inwards as you push through a stride) is natural and shouldn’t be corrected, it’s part of the foot’s shock absorbing action. The traditional thinking is that pronation causes all sorts of other lower leg injuries and so fixing it will fix those problems too. This is far from proven…
Now science is starting to overhaul marketing patter, some parts of the running world (and scientific community) is realising that maybe we’ve been going in the wrong direction for a number of years(!). Minimal shoes (less or even no heel rise, low cushioning, little or no stability control) are on the rise and the market is becoming flooded with a multitude of options. Some of the major brands and starting to join in, Saucony have recently reduced the heel height on two of there flagship ‘traditional’ shoes from 12 to 8mm in response to the research work that has been carried out. it’s great that the some shoe manufacturers are becoming proactive in this area, but at the same time it is creating many shades of grey for runners trying to decide what shoes they need, I’m now pretty familiar with the confusion the choice presents! 
One of the biggest issues I now read and hear about is the experiences people have in most running stores. I would guess that 90% of running shops assess runners shoe requirements based on flawed theories & techniques. My personal experience of this was when I returned to the shop I originally brought my first pair of, very standard, Brooks shoes. On the first trip to buy my 1st proper pair of running shoes the shop assistant got me to run on a treadmill and videoed my running from behind. The assessment was that I had a bit of over pronation (ankle dips inward on foot contact with ground) and duly found shoes that (after another treadmill run) corrected my pronation.
In the year since I got those shoes I went from doing my first races to going under 01:25 in a half marathon, by summer 2011 I was racing in some of the lightest Adidas racing shoes on the market without any problems. I’ve since run a sub 3 hour marathon in them too. I returned to the same shop to investigate replacing the ailing Brooks, they popped me back on the treadmill and the assessment was that my running gait/form was unchanged. The advice was to buy a pair of the slightly newer version of the same shoe, which was fundamentally the same as those I was looking to replace. My option is that my running now doesn’t suit bulky, highly cushioned shoes so now I’m now running almost exclusively in the Adidas racing shoes (with some excursions in the Saucony’s), but I plan to build up my mileage in the Saucony Kinvara’s. Ultimately a lighter replacement for the Brooks needs to be found!
The way most shops work out what shoes you need is a product of a lack of scientific understanding, some misplaced assumptions that the way to address running injuries is to ‘fix’ them with shoes that correct aspects of the running mechanism that we wrongly think need correcting and a good healthy dose of marketing spin. There are shops out there (in the US) which are bucking the trend, but in the UK it’s really up to you and the internet!
Some shoe suggestions if you want to explore more minimal shoes include; the Saucony Mirage (only 4mm heel and some light pronation control), this is the slightly more stability orientated version of the Saucony Kinvara’s. Alternatively the Saucony Guide 5 and Triumph are the more regular shoes that have been reduced from 12 to 8 mm heels and lightened a bit (less material in a shoe = lighter weight!). One is a neutral shoe (no pronation control) and the other has some anti-pronation features. By the way I’m not sponsored by Saucony in any way, they seem to be one of the mainstream manufacturers putting in effort to adapt to this shift in thinking on how we run. New Balance (Minimus range), Nike (Free) are also in on the act. I would recommend having a browse on the US online store just for reference, they have a massive range of shoes and very detailed information that allows you to compare shoes.
It’s all a bit of an exercise in exploring the options and experimenting with what suits you as a runner. You can stay with the ‘safe’ traditional shoe that has prevailed in the mass market for the last few decades or try out a different approach (based on scientific work that so far is hard to refute) that offers to take you back closer to how humans have run for the past 10,000+ years….it’s an interesting choice if you ask me!

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