Today’s post is a summary of a lecture symposium that I attended a few months ago. The lecturer was none other than Irene Davis, a well respected physical therapist, biomechanist and barefoot running expert. Dr. Davis is the director of the Spaulding National Running Center at Harvard. The few paragraphs that follow are to present the material that Dr. Davis discussed during her lecture, and to give some personal thoughts.
It may not surprise you, but Dr. Davis was a huge advocate of barefoot running. She gave several personal and patient related anecdotes about the therapeutic benefits to running barefoot. Also, to cement the facts of her argument, she threw numerous peer-reviewed and published articles at us.
Her first point of emphasis was the biomechanical concept, ground reaction force (GRF). GRF is defined as the force exerted by the ground on a body in contact with it. In other words, if you punch the ground it will most likely hurt because the ground will produce a force acting back onto your hand. The larger the force applied to the ground, the larger the force applied back onto the object (in this case your hand). However, you can decrease the effect of the force by producing the force over a large amount of time. Lets use the punch example again. If you place your hand on a wall as if to punch it and apply 100 pounds of force over 10 seconds you probably will only feel slight pressure applied back to your knuckles. However, if you strike the wall with 100 pounds of force over 0.5 seconds (like a punch) you will likely do some damage to your knuckles. In both cases, the same amount of force was applied, but subsequent reaction is decreased when spread out over a larger amount of time. This is called loading rate.
Back to running.
This brings me to the next topic, foot strike. When people run, we see a few general patterns of foot strike. Foot strike is how the foot initially makes contact with the ground after each stride (aka at the termination of swing phase). The different types of foot strike were grouped into a few categories, and to simplify they can be either rear foot strike (RFS) or forefoot strike (FFS). RFS is when your calcaneus (heel) makes contact with the ground first, and FFS is when the ball of the foot strikes the ground first. There are three benefits to FFS, 1) decreased loading rate, 2) no impact peak which is present in RFS when the calcaneus strikes the ground, and 3)allowing the arch to drop to absorb force (more on this later). Decreasing loading rate and having no impact peak, decreases the amount of force exerted up the kinetic chain on hard tissue structures (aka bones and joints). With a RFS pattern, common problems such as tibial stress fractures, shin splints, and knee/ hip pain was prevalent. With the FFS, greater stress is applied to the soft tissue structures. Dr. Davis says that barefoot running forces the runner to strike with the forefoot. Please refer to the figures below of GRF plotted vs. time.
Does running barefoot strengthen the intrinsic foot muscles? Dr. Davis’ research says that it does. Is this important? Yes! The intrinsic foot muscles, as well as the extrinsic eccentrically contribute to force absorption by allowing the arch to drop, which is what its supposed to do! Dr. Davis believes that giving orthotics to someone with a non-congenital flat foot, only exacerbates the problem by never re-educating the muscles to fire like they are intended. She believes that orthotics (or arch support) should be of temporary service to the patient or client, and that they should be weaned off of them progressively. Dr. Davis further stated that barefoot running is a functional and fun way to strengthen the muscles of the feet.
The last point that I will discuss is the use of minimalistic footwear. Dr. Davis prescribes the Vibram five-finger shoe to her friends and clients, because she says it allows the foot to act like a foot while providing some additional protection. She also made the claim that there are other minimalistic shoes out there that serve the purpose, and that typical running shoes with large heel pads are only increasing the prevalence of rear foot striking. She claimed that people think that because of the built in arch support and increased heel protection, it decreases the force placed onto the body. She said that this could not be further from the truth.
So what are my thoughts?
1. Foot strike patterns–>It is hard to debate her biomechanical analysis of foot strike patterns and gait mechanics. So, I am going to believe the source on this one and understand that it is probably best to strike on the mid or forefoot when doing repetitive running. Furthermore, watch the best athletes in the world run. Whether you are watching Olympic track and field or the NFL, those athletes are not running heel to toe.
2. Orthotics–> I really liked what she said about weaning the patient off of orthotics. She used the example of a neck brace. When a person injures their neck, do we keep them on a neck brace forever? Of course not! We allow the injury to heal, regain range of motion, and strengthen the musculature around the neck to do its job…hold the head up! In using this example, it makes sense that we should allow the foot to do its job by allowing the arch to drop and absorb force. Pronation is a natural part of gait, we just do not want it to be excessive. On the other hand, if the flat foot is congenital or architectural, this may not apply.
3. Minimalistic footwear–>I like minimalistic footwear. I am on my 4th year of wearing minimalist footwear, and my feet and knees feel great! Can I attribute all of my painlessness to my footwear? I am not sure, but I don’t think so. I agree that intrinsic and extrinsic foot function is of utmost importance for health and performance, but I am not going to agree that the best way is barefoot running. It very well maybe, and obviously there are many benefits of allowing the foot to act like the sensate instrument that it is. However, there is more than one way to skin a cat, but I am partial to strength and conditioning. A well structured lower quarter resistance program will awaken the neuromuscular system to allow proper functioning. A little trick to get more bang for your buck is to warm-up and do posterior chain and standing exercises barefoot! I do not run barefoot. I like the concept, and understand that it may help you adopt a more natural footstrike, but you wont ever catch me running down Broad Street unprotected! In addition to this, I would not buy the five-finger shoes. I will keep buying my $80 minimalistic shoes, train hard, run with proper mechanics and use the $30 I saved on other things that I enjoy (see picture below)!