by Nicholas A Campitelli DPM FACFAS
Has anyone ever pondered the fact that almost every shoe we put on our feet contains a “heel”? This is true whether it is a $200 motion control running shoe or simply a dress shoe that has the ¾-inch heel to accommodate our perfectly hemmed slacks. Let’s not leave out the eye catching high heels that we all tell our patients are biomechanically inappropriate.
Surprisingly, it’s not simply 1 ½-inch pumps that can be wreaking havoc for our patients’ feet. It may very well be the majority of shoes that most of us are wearing.
Is the heel still necessary, especially in a “running” shoe?
The running shoe has many origins but many agree that athletic shoes began with a canvas top and rubber soled shoe that became known as a sneaker when U.S. Rubber used the brand name Keds to sell the first sneakers in 1917.1 The next major milestone came in the 1970s when William Bowerman and Phil Knight created the Nike running shoe. These early shoes had little if any cushion and for the most part had a negligible heel.
Over the next 40 years, we have seen the height as well as the cushion gradually increase. These developments inadvertently made runners adopt a “heel to toe” gait or “heel strike” when running. Bowerman and W.E. Harris authored a primer entitled Jogging: A Physical Fitness Program for All Ages in 1967.2 In this very popular book, they noted the most efficient way to run should be landing or striking on the heel first. The authors specifically stated that forefoot striking is incorrect and not the proper way to land.
Bowerman and Harris had no scientific basis for this explanation. Several years later, they went on to create a running shoe that contained a cushioned heel. They speculated that in order to run faster, one should stride longer and that by striding longer, runners needed to land on their heels. This is one of the “primitive” reasons for the introduction of a cushioned heel. As far as increasing our speed or becoming an efficient runner, we now know from the work of Daniel and colleagues that longer strides are not as important as cadence.3
This heel height has been referred to as “drop,” the distance in height between the heel of the shoe and the forefoot. Today, traditional running shoes have an average drop of 12 mm with the heel being 24 mm and the forefoot being 12 mm. This design encourages an unnatural gait, resulting in the heel hitting the ground first and followed by a rapid “slapping” of the forefoot.
A literature search will yield numerous articles discussing running biomechanics but unfortunately, we have yet to see any hard evidence as to what is the proper way to run. The majority of Root’s theories about running biomechanics involved heel striking first.4 However, that is simply what they were — theories. I agree that his work and publications are magnificent, wonderful and have meant a lot for our profession. However, we cannot use this as evidence-based medicine to treat our patients’ disorders in every aspect.
This can be very difficult to swallow but pronation as described by Root becomes irrelevant when we describe forefoot striking as we see pronation occurring with the entire foot and then ending just as the heel touches the ground. His definition, although described as movement of the foot, focused on the motion of the subtalar joint.4 Pronation in this manner becomes an ideal shock absorber, utilizing the motion of the midtarsal joints as well as the subtalar joint.
Root’s evidence came from previous texts, examination of patients and cadavers to then create what he referred to as “normal values” for the given range of motions. Root never went on to produce any randomized trials or studies that could demonstrate that injury was more likely a result of not having the so-called “normal values.”
Ankle equinus is one specific pathology Root discussed that has become very important when discussing lower extremity injuries. Root described ankle equinus as the inability to obtain at least 10 degrees of dorsiflexion at the ankle joint.4 He also emphasized that when we assess the subtalar joint in a neutral position, the ankle joint should be at 0 degrees with respect to dorsiflexion and pronation. Root also noted that by having the ankle in a plantarflexed position, we see uncovering of the talar head and thus an increase in the propensity for the subtalar joint to become hypermobile.
Interestingly enough, what happens when we place our foot in a traditional running shoe? We plantarflex the ankle joint and function with our foot in ankle equinus. We spend so much time educating patients on the effects of ankle equinus and runners abandon it all within seconds by lacing up a traditional running shoe.
Editor’s note: Dr. Campitelli has disclosed that he is an unpaid Medical Advisor for Vibram USA.
1. Available at http://news.bbc.co.uk/sportacademy/hi/sa/athletics/features/newsid_3935000/3935703.stm.
2. Bowerman WJ, Harris WE. Jogging: a medically approved physical fitness program for all ages. Grossett and Dunlap, New York, 1967.
3. Daniels J.T. Daniels’ Running Formula, Second Edition. Human Kinetics, Champaign, IL, 2005.
4. Root ML, Orien WP, Weed JH. Normal and Abnormal Function of the Foot, Volume 2. Clinical Biomechanics Corp., Los Angeles, CA, 1977.