Footwear is as essential to fitness as a bottle of water. And like all sporting equipment, footwear is rapidly evolving as research progresses and understanding of human biomechanics improves. Popular books like Born to Run by Christopher McDougall (Vintage 2011) and extensive marketing campaigns for “fitness shoes” have made healthy footwear—and maybe even no footwear at all—a hot topic on the hiking trails and in the gym. Chances are you or your clients have seen Vibram’s FiveFingers® shoes and have questions about starting a barefoot training program. As a movement professional, you need to fit yourself into the great foot conversation.
Footwear: What Is the Big Deal?
Scientific arguments from researchers in the barefoot and minimalist footwear movement are fairly straightforward. Footwear does not grow on trees; it is an unnatural, modern habit that is unnecessary for healthy human performance. The human body does not require shoes to stabilize the joints and keep lower-leg tissues healthy (Rossi 1999, 2001; D’Août et al. 2009).
More important, footwear can limit the natural motion of each joint during a regular gait cycle (Bergman et al. 1995) and increase the incidence of knee osteoarthritis, back pain and hip degeneration. With this data in the literature, it is no wonder people want to ditch their footwear and take their daily 3-mile run sans shoes. But how exactly are shoes causing inappropriate wear of our human tissue?
Losing Our Nerve
The sole of the foot is the first interaction between man and ground. Sensory nerves collect data on temperature, pressure and terrain, staying finely tuned by constantly reading changing environments. Processing the same data every day for decades creates a physiological response that limits the nervous system’s ability to process new data. This makes balance and locomotion less natural and increases the risk of falls, ankle sprains or other lower-leg injuries (Nurse et al. 2005).
Limiting Full Joint Motion
Foot position is affected by two groups of musculature: extrinsic and intrinsic. Extrinsic foot muscles have one end in the foot and the other end somewhere up in the leg. These muscles always move the foot relative to the lower leg. The three muscles of the calves are all extrinsic.
Intrinsic foot muscles have both attachments entirely within the foot. Intrinsic motions move one portion of the foot relative to other foot joints. One example is the muscle that moves your pinkie toe out and away from the other toes (abductor digiti minimi).
Wearing shoes is like putting a limb in a cast after a bone break; muscular tissue rapidly atrophies without regular use. As the smaller, fine motor skills of the intrinsic muscles weaken, larger extrinsic muscles begin to compensate, developing inappropriate tensions.
The human skeleton is designed to bear weight on the vertical axis. Positive heels—any heel height above the ground—shift the skeletal position at all joints above the ankle (de Lateur et al. 1991). Although slight, the resulting increase in knee and hip flexion creates a gait pattern that causes friction and leads to joint inflammation.
It is also important to note that while footwear choices like high heels are obvious culprits, most shoes, including many athletic styles, have heels up to 2 inches high.
Fresh Feet and the Urban Jungle
Despite all the data supporting barefoot theory, the flip side of the au naturel coin is that most exercise surfaces are just as unnatural as our shoes. The hardness of concrete, while somewhat similar to the firmly packed dirt of a trail, still exceeds the natural biological forces created by the interface of natural on natural. The increase in impact, made worse by poor walking or running mechanics, can increase the risk of stress fractures (Warden, Burr & Brukner 2006).
The traction between skin and dirt or grass is also much less than that between skin and artificial surfaces like asphalt. The interface of bare feet on asphalt creates greater tension on the surface tissue, which can increase damage to the top layers of skin. Finally, modern-living terrains sometimes contain debris that can injure bare feet. For all these reasons, many foot specialists are not fond of shoe-free exercise.
Another issue is that many who start a barefoot or minimalist shoe exercise program ignore the basic exercise science laws of appropriate progression (see the sidebar “Training Feet”). Feet that have been bound for decades cannot bear the load of the human body without some sort of training. Just as you wouldn’t hand a 150-pound weight to a client fresh out of an arm cast, you shouldn’t send a shoeless client out unprepared. It is very likely that injuries sustained in a barefoot training program come from a combination of deep foot-muscle weakness and poor mechanics.
Is Barefoot the Answer?
Spanning over two decades, the research on footwear and its impact on total-body health is fairly extensive. Shoes have many detracting qualities, and data supports at least a change to more flexible, spacious and flat footwear. As for all-barefoot exercise, research is limited and new, but it is trending toward integrating this lost body part back into the foreground of exercise training (see the sidebar “Sample Foot Exercises” for some basics).
Many footwear companies have begun to create minimalist footwear—shoes that allow more natural biomechanics while still offering a bit of protection from modern surfaces. For most people, these options provide the best of both worlds, enhancing health and performance while minimizing risk of injury.