Should we be wearing barefoot running shoes?
Running is probably one of our most fundamental movements and is often learned naturally. Likely are easiest ways to exercise and is one of the most celebrated sporting events ever. From the 100m sprint to the long enduring marathons, running commands respect from all. With big events comes big money and big corporations to follow, which is not necessarily a bad thing, but does open up the door for controversy. To look at running, you first have to look at the anthropology. We cannot leave out the arguments that are risen by evolution. We humans have been evolving for many years, and were designed by nature to walk and run barefoot. Only in the last fifty years have we started to wear supported, cushioned, stabilized shoes. If our bodies were designed for running, how come so many runners are injured so frequently? How come big companies pour billions in marketing to say their shoe is the best when our fundamental human nature is not to even wear shoes? I am going to discuss why barefoot running shoes or “minimalistic shoes” (interchangeable) are a more desirable and smarter choice of footwear for a runner. Barefoot running and minimalistic shoes can change the foot pattern to forefoot and mid foot striking that leads to a safer, and can provide a more efficient energy expenditure during running. We will define our term safer, as in any modes of decreasing the risk of injury while running and reducing impact forces given to the body by running. We will then define energy efficient increases in as improving oxygen consumption and energy utilization. This in turn will allow the runner to proceed for a longer duration. This essay is only regarding running in a form of duration, we will not be speaking of performance sprinting; but much more research is out there! First things first, let’s see what is happening at our foot when we are either wearing minimalistic shoes or standard athletic shoes.
Initially, shoes limit proprioception, which cannot be argued. Sensory feedback was one of our first evolutionary traits developed and we still use it daily. We need this feedback from our plantar surfaces on the feet to sense the characteristics of the ground to tell us how hard or soft the surface is (2). Having plantar proprioception tell our nervous system what choices to make regarding our running such as stability or strike angle (2). When we run with a big cushioned shoe, with an elevated heel and an inch of cushion and air pockets, we are depriving our body of valuable feedback that can help prevent injury. If we run nearly barefoot, we can have that proprioception and allow our body to tell us how to run. Secondly, wearing these cushioned shoes can have an adverse effect on our feet and actually damage what we are trying to protect. The skeletal muscles of the feet are like any other muscles, if you don’t use them, they will get weaker (2). This is especially true of children when the body is still growing (2). If a child is given cushioned shoes at such a young age, how will his feet develop strength and how will his bones adapt to stress? Our foot is an arch, it is designed to absorb impact, you deprive your muscles of the impact, and it will get weaker and not be strong as it could have been (2). Let us look at these foot strikes and the variety of which causes the best effect.
We will be looking at the effects of foot strikes, them being rear foot strike (RFS), mid foot strike (MFS), fore foot strike (FFS), and non-rear foot strike (NRFS). This variety of foot strike pattern is derived from the runner and the bio-feedback of the actual foot strike itself. Thus causing a minimalistic runner to tend to a FFS while a standard shod will tend to adopt a RFS pattern. (3) This in turn links us to the question at hand, “should we wear barefoot running shoes?” Well, what is a barefoot running shoe? Typical athletic running shoes consist of three layers: insole, mid-sole, and outsole. The insole is usually made of synthetic material such as nylon. The outsole is most often made of a hard rubber surface. The midsole is usually made of foam to provide a cushioning for the sole. This is where the differences lay among the two different shoes, a standard shoe has a cushion and raises the heel 8-16mm. The minimalistic shoe ranges from 0mm to 6mm (3). This is where the greatest change occurs for the difference in shoe. A minimalistic shoe that is worn typically causes the runner to adopt a NRFS, whereas a standard shod frequently adopts a RFS pattern (3). First, let us take a bite of the credibility of the expensive state of the art running shoes.
Would you be surprised if I told you that pricy athletic shoes that use words such as “state of the art,” “cushioning impact,” and “advanced technology” had a greater injury frequency of 123% compared to the cheapest running shoes? Well, it’s true (5). Unfortunately, we are susceptible to advertising claims or pictures and think nothing of it. An interesting study was done by Br F sports med, that showed the hazards of deceptive advertising in athletic footwear and comparing the cautiousness of runners and how they selected their form while wearing the shoes. The more expensive and elaborate messages attached to these shoes, the more careless the wearer was while in use. Researchers tested the impact forces on these shoes, and surprisingly they tested with higher ground reaction force than the less expensive shoe. On the other hand, with the cheapest shoes with no extravagant message of super cushioning, the user was more cautious and showed a reduction of impact forces given (5). This is poised to show that an expensive running shoe is not always the best way to prevent injury and elaborate advertising has a limit (5). Now, let us look at what is the main differences in minimalistic shoes and standard athletic running shoes and see what all the hubbub is.
Running in itself is a cyclic movement that pounds the surface and the body pays the price. The effecting joints are absorbing that energy over and over during this movement. Our first goal can be to reduce the impact forces that are absorbed by the bodies effecting joints and muscles. Let’s look at the hip, knee, and ankle during foot strike; they are the primary power absorbers during running. Researchers at The International Journal of Sports Physical therapy came to the concluding findings that FFS pattern lands with an effective force of -6 W/kg of power absorption in the knee and hip, while RFS pattern landed with forces of -13 W/kg of absorption. Looking at the ankle, FFS lands at -9 W/kg while RFS landed with -5 W/kg of power. As you can see, the forces from FFS tend to shift from knee to ankle, while RFS rely more on knee absorption. However the total impact forces combined of FFS land with an approximation forces of -15 W/kg, while RFS landed with 23 W/kg of power (6). Adopting this method of running is an effective way of reducing the overall impact forces applied to your body during this cyclical movement. Runners often complain of patellofemoral pain and accounts for 20% of all runner related injuries (3), therefore reducing the impact forces of the knee can be an effective way to prevent knee injuries.
In regards of injuries, we have to look at frontal plane movement while running. High knee frontal plane movement is known to correlate with the increased medial compartment knee loading and is often linked with degenerative knee disorders. Knee movement in the frontal plane causes a higher knee impact loading causing medial tibiofemeroal osteoarthritis (1). Also it has been suggested that running induced frontal plane knee movement contributes to the pathomechanics of the patellofemoral pain that is very common among standard shod runners (1, 3). There was significant statistical difference in knee abduction taking place among fore foot strikers, it being less than rear foot strikers; indicating less chance of injury among FFS (1). Minimalistic runners often land with their foot more vertically aligned with their knee and also their hip which in turn provides less over stride (2). With more alignment, we also eliminate cross swing and unwanted oppositional forces throwing us off balance.
Looking at the efficiency of a runner, we have to look at the mechanics of the individual on how they land, and also the length and stride frequency. Starting from the shoe itself, we cannot forget we have to account for its mass. A standard athletic shoe weights approximately around 350g which is 200g more than a minimalistic running shoe (4). With every 100g costing about 1% more of cost of transport or COT (mL 02 * kg -1 * m -1) this in turn totals to a savings of 2.41% and 3.32% (4). When the shoe weight is held a constant along with stride frequency, a minimalistic running shoe landing with FFS is about .74% more economical than a standard shod wearer with a RFS (4). It is also noted that it is possible that wearing a minimalistic shoe allows for more of an elastic energy effect in the arch of the foot. The moment the foot strikes and going into mid-stance, then it recoils like a spring during the second half of the stance (4). There is another aspect that cannot be overlooked, which is minimalistic runners undergo less knee movement comparing to standard shod wearers who exhibit more knee flexion (4). It is estimated that a 1% increase in running economy based on the cost of transport model, can allow a runner to increase his/her speed by 0.049 m•s-1. Thus having a mean energy efficient increase of 3% can allow a marathoner increase his/her aerobic speed by 0.147 m•s-1 during a race and can save the runner approximately 9.5 minutes (4).
With all that said, it still can be a strange transition to move from a brand new pair of Nikes to the opposite of nearly having nothing on your feet. We have to remember not to be fooled by deceptive messaging and extravagant words and think our shoes our protecting us; our body knows how to protect us. The evidence is there and illustrates clear cut reasons to make the transition. You will eliminate a significant amount of unnecessary ground reaction forces from foot strikes and reduce the strain on your knee and hip joints. Not only that, but you will also ease the pressure on your medial side of the patella femoral joint and reduce the chance of injury. Running more efficiently because you are light on your feet, and running longer because you don’t have to carry such a heavy shoe with you and a reduction in knee flexion. Eliminating cross forces from a reduction in knee abduction. Letting your foot do what is it designed to do, be a supportive strong elastic spring and allow your body to be receptive to bio-feedback it takes in as you run.