Original article published by Natural Running Center.
Minimal shoes give the runner or walker an experience closer to barefoot. One starts with the least amount of shoe that is safe for them today and then gradually reduces the protection and support as the foot strengthens. A shoe should allow you to walk or run not enable you.
One of the main benefits about being truly barefoot is maximizing proprioception, the valuable sensorimotor information we receive from the foot/ground interface. The foot’s dense proprioceptive system plays a critical role in the activation and efficiency of muscles controlling gait, posture and alignment. When we introduce a layer between the sole of the foot and the ground we add a layer of sensory insulation.
So let’s look at the role of a critically important aspect of the shoe – the insole layer, the layer that is in contact with the foot. Insoles have traditionally been broken down into 3 main categories; cushioning, support, and custom orthotics. Recently a 4th category, foot strengthening or proprioceptive feedback insoles, has been introduced.
1. The cushioning products use terms like shock absorption and energy dissipation .The premise is that the material, through physical changes in the material properties and / or material breakdown, dissipate harmful impact energy and provide cushioning. Top products in this category, SofSole and Spenco, use materials with viscous properties. The viscous property materials tend to be heavy and the softness of the product dampens our interactions with the ground. This does not produce the desired effect for efficient walking and running activities.
2. The second category of insoles support the foot, and most commonly the foot’s medial arch. Variations of these insoles exists which feature wedging effects to alter pronation.
These insoles mimic the custom orthotic concept. Variations of these insoles also exist where you can heat form the insole to match your foot, making it more like a custom orthotic products. In the support category are Sole, A-Line, and Superfeet.
3. Another device is the custom orthotic. The Websters’ Dictionary defines an Orthotic as “a device (as a brace or splint) for supporting, immobilizing or treating muscles, joints or skeletal parts which are weak, ineffective, deformed or injured.” Although typically not sold at retail, virtually every retailer has a percentage of consumers who come in and must ensure that their orthotic will fit into their new shoes.
Although I believe there are several structural flaws that benefit from orthotics; we often take a structurally normal foot which has atrophied through years of bracing and support, make a cast of the weakened foot, and make a support to brace the weak foot. We allow the foot to continue to weaken and make another pair in a year. Making the foot reliant on a brace or support is in opposition to strengthening and rehabilitating the foot so it can become a self-supporting structure. Once a joint is braced it will often require bracing indefinitely until an active rehab is prescribed.
Athletes embracing healthy foot movement desire the following:
a) We don’t want sensory insulation
b) We want full foot Range of Motion
c) We do not want excessive bracing, cushioning or support
4. A unique category of insoles is a Proprioceptive Based insole by Barefoot Science. This is not a new concept – Barefoot Science insoles have been around for almost a decade and the underlying science is decades old. The insole focuses on the use of the body’s sensory system to introduce a mild stimulus to the foot’s center. The body’s natural response is to move away and a series of continuous and minute muscle contractions begin. The insole works with a progressive series of inserts, like progressive resistance training, to gradually introduce a muscle strengthening component to the foot. So as opposed to the concept of brace or cushion, the goal is strengthen and rehabilitate. For those questioning the benefits of the brace/support and cushion/insulate products Barefoot Science is a product to test. Your body will answer if it is right for you.
Another interesting aspect of Barefoot Science is how it interfaces with the foot. Most insoles focuses on supporting the foot’s medial arch and, depending on product, the transverse and lateral arches. The shape and concept behind Barefoot Science is in interfacing with the foot’s center of mass. This key region is also aligned with the body’s line of action through the foot and thus it creates a dome like effect that the foot can rotate about. From an anatomical point of the view the hip is like a ball-socket, the knee is like a simple hinge and therefore the foot, to interact multi-directionally with the ground, needs to have a ball-socket multi-directional capacity also. This aspect is especially beneficial for those running or doing activity on uneven surfaces.
Apart from the sock, the insole is the layer in most immediate contact with the foot. The features and benefits of Barefoot Science brings the benefits of foot/ground interface inside the shoe to the foot/insole interface. You can also wear in daily footwear providing progressive barefoot like stimulation with every step taken. This can shorten the transition time associated with the minimalist shoes and reduce discomfort and potential injury.
Through athletic history coaches have known that improved foot strength translates into a more efficient and less injury prone movement. The natural suspension of the musculoskeletal system is capable of providing the shock absorption and support our body requires as well as spring enhancing movement economy.
Insoles focusing on the strengthening and rehabilitation of the foot make the most sense. Barefoot Science insoles are ultra-light weight, flexible, and come in full and ¾ length. Barefoot Science makes sense for not only minimalist runners but for the entire shoe wearing population desiring stronger feet and better posture
Mark Cucuzzella MD FAAFP; Professor West Virginia School of Medicine