Barefoot versus Shod: A running controversy or a life style epiphany?
There seem to be hundreds of bloggers, twitters, and web contributors jumping on the barefoot band-wagon. Is there a benefit to running barefoot? Will it make you faster? Will runners be less prone to injury? Are shoes really causing the problem? There are so many questions and quite honestly little true science to prove the benefits of one position over the other. So let’s look at this latest buzz word controversy from a common sense perspective. Believe it or not I think you will agree that with some clearly directed questions, we all will see that we are arguing the same position, but really don’t want to admit it.
Remember the concept of Occam Razor, and the corporate equivalent – KISS: Keep It Simple Stupid. Do not underestimate the obvious and simple. As well do not ignore the aspect of natural selection and that as complex organisms we have developed organs and systems that are very purpose driven.
As I write this you will see that on one hand I try to put forth a logical argument and a path of logic that will lead the reader in a desired direction, however at times, unless you read the entire proposition, you will think I am going all over the place, or at least around in circles. This is analogous to the discomfort and injury cycle associated with footwear and orthotics. So before criticizing please consider that as I paint the big picture here, I am pulling concepts from gait biomechanics, physics, bio-chemistry, bone physiology and muscle physiology, and others. In some cases aspects of one field of science will act as a contributing building block to another. And just to make things a little more interesting I may also throw in some long standing positions that are well accepted and embedded into the worlds of the academia, podiatry and the footwear industry.
One: The foot – basically made of muscle, bone and connective tissue. Without spending lots of time digging up some supporting science, is there anyone out there who doesn’t agree that a strong foot would be better than a weak foot? Is there anyone out there who thinks that increased ROM (Range of Motion) at the joints would not be better than decreased ROM at the joints? Is there anyone out there who doesn’t believe that targeted exercise can result in an increase in strength and flexibility? Is there anyone out there who believes that a foot, which is muscle, soft tissue and bone, could not be subjected to an exercise regimen that would result in a stronger, more flexible more effective organism? I call it an organism because as a living structure it is capable of adaption at a cellular (micro) level and a morphological (macro) level in response to the environment, and more specifically the strains and stresses introduced by the environment.
This, in itself is key! The organism reacts to strain and stress at every level. The bones react to strain and stress and lay down bone tissue as a response. Repeated intermittent stress causes hypertrophy, chronic compression causes atrophy and chronic tension causes hypertrophy. These changes result in changes in the shape of articulations further resulting in changes to the direction of force vectors when muscles contract, and thus alter mechanics. The atrophy and hypertrophy of bone will alter the bone’s center of mass. Thus from a biomechanics point of view the magnitude of the forces, torques and energies that exist as our body acts and reacts will also be altered. Logically if these changes are in response to a negative environmental influence the resulting changes may encourage a negative less productive NET result. The NET result may be performance decreasing and/or injury causing.
A good example in all of this is the formation of a bunion. As the bunion forms the joint becomes more suspect to shearing forces at the joint, directed most commonly, laterally at the distal end of the hallux. As these shearing forces increase, as a result of the changes in angle, further tension is put on the capsule and thus more bone material is laid down as a defensive mechanism, and the cycle of increased stress and bone formation continues. To further compound the issue, the now enlarged bunion is more suspect to the intermittmnet stresses created in the foot-shoe interface at toe off, and even more bone material is laid down further adding to this vicious cycle.
So where is all of this going? Well properly introduced strain and stress can be beneficial, after all exercise is really only strain and stress. The field of orthodontics have been using strategically introduced strain and stress for years to promote dental alignment by the remodelling of the mandibles. Improper strain and stress can be detrimental, as shown in the bunion example, as well it can be a contributing factor to genum varum and genum valgum.
The key is in understanding, with respect to the foot, that the strains and stresses caused by a shoe will ultimately lead to a remodelling of the foot that is less than ideal, simply because the shoe environment is less than ideal. The resulting change in mechanics will also be less than ideal, producing less than ideal performance, and greater than desired forces and energies resulting in chronic and acute injury.
What else is happening at the level of the foot?
In the big picture the foot needs to subjected to an environment that encourages freedom through all of its ranges of motion as well as controlled strain and stress. The combination of these two encourages a foot capable of achieving ideal mechanics resulting in ideal performance and reduced injury. Ideally the foot must operate in a tri-planar capacity and the reduction of ROM in any one plane cannot help but to influence the ROM in the other planes. This can have profound effects on performance reduction and injury promotion. This is especially important when we look at the role of orthotics and motion control footwear whose sole purpose is to artificially reduce ranges of motion.
The foot is also a very essential proprioceptive organ whose role from a gait perspective maybe defined as guidance, cushioning and support, yet in conjunction with that is a role of proprioception or an understanding of the environment’s support surface. This is essential for the foot to offer the cushioning, support and guidance that it is naturally capable of. Unfortunately we have, for centuries, been insulating our foot from its environment and reducing its ability to function as this proprioceptive bell weather for the body. Most of us have been with kids who are barefoot, and we have stood back in amazement as they have clambered over rocks and sticks and gravel almost unaffected whereas we are hobbling off balance because of the super sensitivity of the soles of our feet. The key thing to acknowledge here is that the proprioceptive component is not originating from the thickened skin associated with the heel pad, or the callused skin beneath the met heads, but from the thin, nerve engorged skin of the midfoot. Drag a finger across the palm of your hand and then across the tip of a finger – the difference in sensitivity is undeniable. Currently nothing in footwear encourages this midfoot sensation required for healthy, ideal gait. Footwear and orthotics both introduce a barrier which reduces the nerve stimulation in the midfoot.
One last note on the foot – its’ muscles. Many of the long muscles controlling the guidance and propulsion phase of the foot are located in the lower leg. However what often goes un-noticed is the intrinsic musculature of the plantar surface of the foot. Whereas most of us think of muscle force generation as “action causing” concentric forces, few of us take into consideration the “action controlling” eccentric contractions. If we think of the foot as a leaf spring and we view the plantar fascia as a sort of connective cable controlling the two ends of the leaf spring, then as the leaf spring deflects, it’s rate of deflection would be controlled by the plantar fascia (later on I will argue that the Windlass Effect is occurring prior to foot strike and thus also plays an important role here). Unfortunately the PF (plantar fascia) has little spring properties being connective tissue and can easily be over strained resulting in injury. Now let’s consider for a moment what other mechanisms are there that could help lessen the load on the PF. The obvious here are of course the intrinsic muscles on the plantar aspect of the foot lying dorsal to, and some integrated with, the PF. So now let’s visualize, in slow motion, the arch deflecting and the intrinsic muscles slowly eccentrically contracting to control arch deflection. It has often been proposed that the intrinsic are too small to provide an significant contribution but I would liken it to the single strand of a rope, wherein one strand my prove to be insignificant, but the contribution of the collective is significant. Where the “whole is greater than the sum of the parts”.
This proposition is key from a couple of perspectives; firstly these muscles must exist for a reason and the concentric contraction of these muscles truly serves no purpose, secondly we know that eccentrically a muscle can develop more force than concentrically, and thirdly we know that muscles, through their series and parallel spring properties, are excellent energy storage units. This energy can then be contributed positively to the gait cycle, at least, and more importantly it can be stored rather than having to be dissipated. The alternative, and more common, here is the existence of weakened intrinsic muscles, unable to store energy properly, and that energy, which must be used or converted (remember grade 9 physics), eventually is dissipated through the destruction of soft tissue resulting in acute or chronic injury. In an ideal sense this foot is a fantastic shock absorbing mechanism, a wonderful work of engineering, in the eyes of Da Vinci.
Summary – keep the foot in an environment that is as artificially stress free as possible, an environment which encourages full range of motion, encourages development of muscle strength, and encourages the proprioception and biofeedback loop that exists in the central nervous system between the brain and the foot. For those so inclined there is also a perceived role of importance of the foot as a component of the sympathetic and para-sympathetic nervous systems. In an ideal state all of these would be encouraged through a lifetime of barefoot gait. Some literature has suggested that only 3% of persons in unshod populations suffer gait related foot pathologies whereas 85% of those in shod populations will suffer a pathology necessitating some form of intervention. However we do not live in environments conducive to being barefoot 100% of the time, nor have we been brought up in a culture that has encouraged barefoot gait from birth, simply removing our shoes does not make us reflective of barefoot. From this ideal perspective of the foot, simply taking one’s shoes off does not make a person truly barefoot, however with proper encouragement and common sense a transition to barefoot is possible.
Gait and Footwear – The real issue here, as I see it, is that there is a part of us that wishes we could run barefoot on soft grass in an idealistic world, and that the world was a simpler, slower moving place. The reality is that few of us live in the tropical climates where we could potentially be barefoot 24/7 and few of us live in regions that are still paradise. For most of us footwear is a necessary evil. There have been numerous studies looking at the effect of footwear on gait, specifically the analysis of temporal, kinetic and kinematic characteristics. All have shown that there are dramatic changes associated with the use of footwear. Although there is a considerable body of research relating to footwear and gait, there are some obvious flaws in the world of academia as it relates to shod versus barefoot. The most obvious of these is that most data collection is done in an academic environment, and the data is collected from the student populations. These students have been in shoes most of their life and have adapted to our hard flat environments that are not necessarily barefoot friendly. Yet we presume to take these “subjects” pull them out of their shoes, throw them on a treadmill and collect data from them under the veil that they represent “barefoot”. This is so far from the truth and such an obvious oversight that it is comical. To compound this academia tends to reward and reinforce the regurgitation of previously collected data so what we get are reams of data collected to reinforce the same old observations and theories.
It has been argued that shoes, as they currently are, have many detrimental effects on the foot and on gait. In a manner as brief as possible, let’s take a quick look at the evolution of the shoe.
Firstly, before the presence of social hierarchies and before the importance of sales and marketing campaigns, there was time when there was no fashion, so there was no fashion versus function proposition. Shoes were worn purely for protection from the environments and the elements. The materials of choice would be that provided by the environment itself, most notably the leathers and hides of the animals that were the food source. The very nature of the materials themselves and the methods to actually manufacture the product would, without doubt, only have produced footwear that was light, thin and flexible and above all, practical and un-inhibiting. Now let’s jump ahead to an era of social hierarchy when nobility had servants and your level of inactivity revealed your rung on the social ladder. In these days shoes also revealed your rung on the social ladder, the more impractical the shoes were, the more sedentary you would be and thus your position on the ladder would be further up. So design characteristics like pointy toes, thin lasts, and high heels became the aesthetics to aspire to. Welcome to the age of shoes screwing up your feet. The wheels have been put in motion for the nurture part of “nature versus nurture” to play a significant role in foot pathologies and gait.
Now just a few quick reminders, the trend for these shoes, the environments for our feet, were unhealthy. And as we have discussed we know that our feet will adapt to these unhealthy environments resulting in unhealthy morphological changes, unhealthy biomechanics and thus shoes were contributing to a whole host of related symptoms.
If we jump ahead a couple of centuries or so to a time when the prevalence of these symptoms came to prominence we see a host of inventions aimed at helping to relieve these symptoms. We are now in an era of science and pseudo science, and an era of salesmen ship and marketing for the purpose of preying on consumer ignorance to sell product. Nowhere is this more apparent than in the footwear business. Back in the early 1970’s the increased popularity of physical fitness and running meant more people were running, and running more often. There was thus an increased frequency and magnitude of gait related stresses on the body, and logically a taxing of the related musculoskeletal system resulting in injury. Gait analysis was still in its infancy, despite the fact that it was some years after Muybridge’s early cinematography. The majority of the testing equipment that was available and capable of providing reliable and accurate data, dealt with the measurement of material compression, and for the shoe industry, this meant measuring the midsole compressions of midsole materials. This was the onset of the cushioning and shock absorption era, the industry became inundated with technologies like Derringer’s Web, Dynamic Reaction plates, Air and it’s derivatives, Gel and its derivatives, to name a few. This was an era of the “cola wars” of shoes and if 5mm of cushioning was good then 8mm would be better, and so and so on. This all under the ipso facto assumption that if the increased participation in running was creating a higher frequency and magnitude of running impact forces, and therefore higher related stresses, then adding more cushioning under the foot would be helpful in reducing running related injuries. Oddly enough this didn’t happen. In fact studies relating to cushioning actually showed that the gait characteristics of a runner actually altered as a response to shoe midsole density and compression. The body itself was regulating it’s mechanics, arguably in an attempt to be as efficient as it could be. This is supported by research looking at the economy of locomotion.
However as advances in technology in the shoe industry was allowing more complex cushioning devices to be manufactured, the technical advances in gait analysis was also evolving. The most notable of these, for this conversation, involved video analysis. Hence was the birth of motion analysis which revealed a considerable amount of information about the magnitude of motion occurring in the lower limb during gait and as a result the speculations on the amount that needed to be controlled – hence the birth of motion control. One of the most interesting things in this field is that as a heel height increases, for example to insert a cushioning device, then rearfoot motion also increases with that increased heel height. Increases in heel heights lead to increases in torque through the subtalar region, increases in rates of pronation etc.. All of these require increases in muscle contribution to control these increased stresses. The result is muscles are pushed beyond their limits as they attempt to control excess motion. Their inability to control and store the related energies results in chronic and acute injuries as the excesses in energies result in soft tissue destruction.
Interestingly enough, as the shoe companies realized that, in their efforts to address the perceived cause of injury, they may actually be further increasing the predisposition to injury, and they needed to look outside of the shoe industry for solutions. Who better to look to for guidance than the field of podiatry? Remember there was an era when most of the major running companies had their own in-house or preferred gait mechanist or podiatrist. This relationship presumably was to seek guidance from these experts as the shoe companies attempted to address these possibly motion controlled injuries, but it also looked great in adverts touting the medical validity of their shoe technologies to the consumer.
Back in the early 1900’s the famous Dr. Scholl is cited as acknowledging a link between foot pathologies and a weakening of the foot’s arch. Unfortunately most everyone overlooked the issue that the arches of the foot were an integral part of a living organism capable of rehabilitation. The course of action at the time was to brace or support the weakened structure, just as you would brace or support a weakened house foundation, which the foot is often compared to. The business of solving gait related pathology through artificial bracing and cushioning was set in motion and capitalism has taken full advantage of it. However, as we now know, if you brace a living structure you create a dependency, and in the case of the musculoskeletal system you encourage an atrophy of the tissues and thus you enter into this endless loop of bracing causing weakening resulting in more symptoms, requiring further bracing. All of this is good for business, if you are in the business of orthotics or motion control footwear.
For the runner this collaboration between the bracing obsessed podiatric type community and the footwear R&D engineers, led to the adaptation of bracing technologies into footwear. Hence the onset of the motion control boom. Interestingly enough as we add to the heel height of shoes to accommodate newer, larger motion control technologies we produce increased torques, energies, and accelerations during the gait cycle, all of which the weakened musculo-skeletal must attempt to counteract and adapt to. Also as we introduce these devices to control motion in one plane, we also effect motion in other planes and thus affect the overall function of the foot.
All in all, this is an endless cycle resulting in dependency and injury. There a number of clues overlooked by the experts that could have taken running, and more importantly barefoot inspired running, in a totally different direction. The first of which was Scholl’s original observation that there was an obvious relationship between the strength of the medial arch and pathology. The industry at that time was not as imbedded in bracing as it now is, so hypothetically, things could have moved in a strengthening and rehabilitative direction. If there had only been a way to profit from it. As we can see the from the footwear and footcare industries, the underlying product development philosophy is embedded in the bracing and cushioning approach. Each industry has fed off each other, and to compound this academia, with its approach to rewarding regurgitation, has meant that these century old philosophies become over researched and over accepted, giving little incentive for the footwear industry to think outside of the box and propose new approaches.
Within the footwear industry itself there was a wonderful clue back in the mid 70’s and early 80’s that would have given a whole new insight into the negative effects that footwear was having on gait. Remember back in the days of the first Waffle trainer, the TRX trainer and others? There was a problem with retail product claims because the runners toe nails were cutting through the top of the shoe. In the infinite wisdom of the shoe industry this area of the shoe was reinforced to reduce product claims. This was the course of action as opposed to any of the leading gait and shoe guru’s questioning why this happening? The secret here is looking at what structural effect this motion has on the foot, at what point in the gait cycle could this be occurring to create such an effect, and what are the benefits of this occurring.
Overall the shoe has evolved into an environment that encourages a bracing of the foot and thus an atrophying of the musculoskeletal structure. The foot’s inability to effectively use its muscles optimally reduces performance and predisposes the system to acute and chronic injury. The shoes of today have also evolved into sensory insulators preventing an accurate priopreceptive understanding of our underfoot environment. Our inability to prepare for initial contact in the gait cycle further predisposes us to injury and encourages continuing atrophy of the musculoskeletal structure. This insulation also removes certain input that would be by received by mechano-receptors and illicit involuntary muscle contractions, thus creating exercise.
There are considerable studies and observations detailing the transition from a more idealistic midfoot strike, to a more rearfoot striking gait. With this comes an increased contact angle between the foot and the contact surface. Of special significance here is that the long bones of the lower limb and their cortical matrix makes them ideally adapted for the resistance of compression. In simple terms the more perpendicular the lower leg is to the support surface the better. In this orientation the posture of the body is more upright and the shock dissipating cartilage of the knee joint is also better oriented to compress evenly and dissipate shock more uniformly. Most runners will observe in their own gait, that as they transition to a lower profile midsole, or to barefoot running, that they naturally transition into more of a midfoot striking gait.
This running posture and orientation to the ground has been proposed to be less injury invoking. All of this is perceived as being typical of an ideal barefoot gait. All of this is also possible if we can introduce to our feet an environment that induces a barefoot simulation and is as free as possible from the restrictions and unwarranted stresses of current footwear. The transition to be being barefoot should involve a gradual introduction of strategic stresses to the foot’s supporting structure. The most obvious of these comes from simply exercising the foot’s supporting musculature, either through planned exercise or though the introduction of devices that create the proprioceptive stimuli necessarily to create these exercises at an involuntary level. For many people their goal may not be to run barefoot, for a whole host of reasons, but to at least be able to run in lighter, less controlling footwear, or to be barefoot at home, or to be less reliant on supporting mechanisms such as orthotics. Regardless of the motivation, there is ample logic to support the notion that running or walking in a manner that is more ideal and closer to an ideal barefoot gait, is healthy and reduces the predisposition to injury. The increased dependency on bracing, supporting and cushioning based footwear merely provides a short term band-aid solution and merely addresses symptoms. The secondary symptoms are the pain and discomfort, the primary symptoms are the foot’s inabilities to control and gait related energies, and the underlying causes are weakened, atrophied muscles. Stronger, healthier muscles in the feet like any other parts of the body only make sense.
For those wanting to make the transition to being barefoot, or at least less dependent on traditional footwear or orthotics there are safe, low risk, ways to do this. There is a growing movement towards the use of bio-feedback or proprioceptive catalyzing products such as Barefoot Science to pre-exercise the muscles of the foot. The insole system works on the premise of introducing a progressive series of pressure inducing catalysts to the plantar aspect of the foot. The presence of the upwardly directed force places an infinite number of minute tensions on the Golgi-tendon organs and muscle spindle fibres. The body’s neural response to this is the involuntarily contraction of the associated muscles. In simple terms the product produces a mild stress which the body wants to reduce, and thus move away from. The only way the body can move away is to contract specific muscle groups thus engaging in exercise. The NET result here is a progressive, low intensity exercise work-out for the plantar intrinsic muscles and the muscles helping stabilize the foot’s arch system. The resulting stronger more flexible foot is better able to provide the cushioning, guidance and support with an end result of increased performance and a reduction to injury and discomfort.
