A Look at How Trainers Affect Training and Running Performance

Following last week’s article “Foot Types & Foot Wear,” I have had quite a few runners ask me the same question, with words to the effect of: “Ok, if the whole overpronation shoe model thing has no evidence, what the hell do I run in!?”

A very good question! But first things first…

Why do we need running shoes at all?

Relax, I’m not going to start preaching about barefoot running (although I’m not going to dismiss it either). But in order to discuss how we decide which trainers are suitable for us, it is useful to re-evaluate exactly what we are buying them for.

With that in mind, over the last couple of days I have been asking the runners I meet what they are looking for when they buy trainers. Collectively, the majority of them produced the following three reasons: protection,support, cushioning.

Protection

If by protection we are referring to avoiding glass & syringes, then wearing something on our feet obviously makes sense. This may well be the main contributing factor as to why, at least in my experience, it is rare to see runners training or racing in no shoes on at all.

Many of us could probably find less hazardous routes on which to entertain the theoretical benefits of barefoot running, but until clearer evidence supports such theories, most of us will probably pass.  However, if we’re talking about protection from running on hard surfaces then we are essentially looking at cushioning (more on that shortly).

Support

By support, most people are referring to stopping the medial arch of the foot “collapsing,” which brings us back to the whole supination/neutral/pronation paradigm used by most running shops to prescribe you a “suitable” trainer after watching you walk or run for a couple of minutes (or in some cases just standing you on a pressure pad, which in itself has no connection to how your foot acts whilst running). I am sure you are already familiar with the process:

• If the arch of your supporting foot drops “too much” you are labelled an “overpronator” and assigned a motion-control shoe that will in theory reduce the “overpronation”.
• If your arch does not drop “enough”, you are said to be an underpronator (or supinator), and assigned a flexible, cushioned shoe to absorb some of the shock that underpronator is said to cause.
• If you are somewhere in the middle, you are said to have normal pronation and are recommended a “neutral” shoe that in theory provides just the right amount of stability and cushioning.

As we saw last week, this model is heavily flawed and unsupported to date by any evidence. It is important not to let fear of injury or promises of recovery persuade you to be herded into one of the three pens (motion control, stability or neutral) however persuasive the sheepdog/sales person may be!

Cushioning

If you regularly run on hard surfaces like pavements, tracks and treadmills, you would think cushioning makes sense. Running shops can be very quick to stress this point if they “see” you as a heel striker. And yet, studies show (Scott, 1990) that peak loads at typical sites of injury for runners (Achilles, knees, etc.) actually occur during midstance (when your bodyweight passes over the supporting leg) and toe off (when your back leg pushes away from the ground).

These studies suggest that impact force at heel contact has no effect on the peak force seen at typical injury sites.

There is also growing evidence that when faced with higher impact forces from a harder running surface, your body makes natural adjustments to deal with the change in impact force – changes in joint stiffness, changes in the way the foot strikes the ground, and also via a concept called “muscle tuning” (pre-activation of muscles prior to impact).

Based on information received visually and from the previous foot strike, the body adjusts how strongly the muscles in your leg contract before the foot hits the ground again. Imagine jumping on a trampoline – your legs naturally stiffen in preparation for the soft landing.

Now imagine yourself jumping onto concrete – your legs naturally become less stiff in preparation for the hard landing. This natural adjustment is the result of sensory feedback from not only the eyes but also from the feet. In other words, the theory is that sensory feedback from the feet following one foot strike helps prepares the body for the next foot strike. If this is indeed the case, could excessive cushioning at the bottom of a trainer inhibit this natural sensory feedback?

Cushioning & injury prevention

The role that impact actually plays in running injuries is not at all clear. Studies by two highly respected biomechanics researchers, Dr. Irene Davis (Director of the Running Injury Lab, University of Delaware) and Dr. Benno Nigg (Co-Director of the Human Performance Laboratory, University of Calgary) have produced contrasting results.

Whilst Dr. Davis’ research links high impact loading rates with plantar fasciitis and tibia stress fractures, Dr. Nigg has found that overall injury rates are slightly lower among runners with high impact loading rates.

One possible interpretation of the above is that leg stiffness, as we considered earlier, is an important factor with certain injuries. Dr. Davis’ research linked runners who had suffered tibia stress fractures with higher impact forces and higher leg stiffness.

If tibia stress fractures are a consequence of high leg stiffness (for which I hasten to add there is as yet no evidence) then maybe runners susceptible to them should try wearing a less cushioned shoe and run on harder surfaces.

Just as we saw in our “landing on concrete” example earlier, in preparation for the harder surface, the body will reduce leg stiffness, which if the theory is correct could reduce susceptibility to tibia stress fractures.

At this stage it is all theory, and I draw particular attention to the words “maybe” and “try”. Always introduce changes slowly and gradually! Give your body a chance to tell you how it feels about the change before you do any harm to yourself!

So what trainers should I buy?

For those of you still clinging onto the hope that I or indeed anyone is going to be able to give you a structured model for trainer selection, I should probably put you out of your misery. There is no model. But do not despair. See it as liberation as opposed to a hindrance.

Yes, some people are recommended trainers and their injury disappears, but plenty are given the same advice and the injury continues. The journey to injury free running is best started with acceptance & application of the following mantra, as used by running coach James Dunne of Kinetic Revolution: Form Before Footwear.

As far as trainer selection goes, Pete Larson, anatomy professor, writer & runner with self diagnosed shoe obsession sums it up nicely: “I can run in just about anything as long as I’m careful to take things slowly and listen to my body.”

This is what I mean by “liberation.”

Part of Pete’s Running Shoe Collection, 2010. (Photo Courtesy of P. Larson)

In my opinion, one of the best things to so far emerge from the barefoot debate is the much larger variety of designs of shoe you can now choose from.

Having seen that heavy cushioning is not necessarily helpful to everybody, you should now hopefully be more confident to test, for example, some lighter trainers. Again, the secret is experimenting to see what feels comfortable for you. Bear in mind that a trainer that suits you for one distance, terrain or speed may not work as well for another.

You could also try trainers with a slightly lower Heel-Toe Drop than you are used to (the difference in height between the heel and the forefoot).

Traditional running shoes have a heel-toe drop of about 12mm. Vibram Fivefingers have pretty much a drop of 0mm. Going straight from 12mm to 0mm is not taking things slowly or listening to your body! There are plenty of 6-10mm transitional trainers on the market which will allow you to experiment more gently.

Though there is as yet no direct evidence for benefits of a lower drop, I personally see much logic in the argument that exposing your feet and legs to varying forces (in a controlled, sensible manner) could potentially make you a stronger runner and reduce injury.

Remember to listen to your body

If you run too far, too often, or too fast in a new pair of trainers, your body will let you know. Many of the running injuries we see in clinic are linked to a runner buying a new pair of trainers and thinking they can pick up their training program from where they left off. It’s more than that. Most runners actually run faster or further the first time they put on their new trainers (we all love new toys!).

• It is vital to respect the fact that your body will often need time to adjust to a new style of trainer. Put on a minimalistic shoe for the first time and run too far and your calves will soon let you know about it! It’s all about taking it slowly and listening to your body.

• If you experience a slight discomfort, treat it as a thoughtful message from your body that you need to break the new trainers in a little more gently. Put them away for a while. Go back to your favourite trainers then re-test the new ones with reduced time or intensity.

• Obviously, if the pain is persistent and affects your running whilst wearing other footwear then get it checked out by a professional, but in my experience most running injuries are the result of either ignoring a warning sign (not listening to the body) or too quick an escalation in frequency, intensity or time.

It may be the shoes, but it’s more likely to be you pushing yourself too much, too soon. Which brings me to my next point…

Use more than one pair of trainers

In order to break in new trainers, you will need to have your all time favorites at hand to wear in between. Your body will warn you if you are doing too much in your new trainers. Listen to it. Put them away for a week, continue with your regular trainers, then go back to the new ones.

Many runners I work with report that exposing their legs & feet to different forces via rotating the trainers they run in leads to (or at least coincides with) less injury. Given that the majority of running injuries are the result of repetitive strain, mixing it up kind of makes sense (and that goes for running surfaces as well). Invest in a few pairs of different style trainers – the chances are you will get your money back by less need for injury treatment!

Have you experienced success by changing to a new style of trainer? Maybe you already rotate different style trainers as part of your running program? We are always keen to hear from you and look forward to reading your comments.

Happy running!

Matt Phillips is a Run Conditioning Coach, Video Gait Analyst & Sports Massage Therapist with over 20 years experience working within the Health & Fitness Industry. Follow Matt on Twitter. And for more great training, nutrition, maintenance info, check out the RunnersConnect blog.