Barefoot versus Shoes

There are two important aspects to the barefoot versus shoes debate. The first centres on running performance. Is barefoot running more efficient and if so many athletes will look towards running barefoot to improve their performance. The second question, will barefoot running reduce the rate of injuries in runners. If so, there may be a reason for all of us to throw out the shoes and join the barefoot running revolution

Differences in Technique between barefoot and shoes

Barefoot running increases plantar flexion at contact. During stance there is an increase in ankle dorsi flexion and calf muscle activity (Divert et al, 2005, Squadrone and Gallozzi, 2009). Also stride length is decreased causing more steps to be taken to at a given running speed (Squadrone and Gallozzi, 2009, Divert et al, 2005) The decrease in stride length is due to both the decrease in the foot weight, heavier foot weights have been shown to decrease stride frequency and also the need to reduce impact forces in barefoot over shod conditions. Decreasing stride length to decrease impact forces can decrease running economy. There appears to be an optimal stride length for each person and each shoe, shortening you’re stride below this point will prove to be inefficient (Cavanagh and Williams, 1981, Hogberg, 1952). Barefoot running is also characterised by an increased knee flexion at impact and the knee is positioned more anteriorly throughout the gait (De Wit et al, 2000). These biomechanical differences between shod and barefoot conditions change muscle activation patterns and the forces on various joints in the body. This will have an impact on running performance as well as the type of running injuries experienced

Running Injuries – Barefoot versus Shoes

This is a difficult question to answer as research on the area is difficult to gather. Injuries will always result being both acute and overuse in both barefoot running and shod running. Changing from barefoot to shod running is likely to change the type of injuries experienced rather than the amount. The question that will be hard to answer is, are there long term benefits of running barefoot over running in shoes? Supported running shoes with orthotics or just medial posting have suggested benefits for patellofemoral pain, ITB pain and possibly achilles tendonitis through control of pronation. The downside is increasing shoe support effectively decreases muscle activation which may inevitably lead to the requirement for more support. Interestingly studies have shown children from lower economic families who have no access to shoes have less incidences of flat feet then children of the same age who have access to shoes (Rao et al, 1992, Sachithanandam and Joseph, 1995). This would indicate arch development is hampered by footwear. The problem is once arches have failed to develop in childhood it may be impossible to reverse those changes into adulthood. Or possibly genetics  may have renders some people with naturally flatter feet with weaker intrinsic foot muscles. In the same way note all people could do chin ups and swing from trees, not all foot types may be able to handle reduced support running. If this is the case shoes will be this persons ergogenic aid that allows for increased training and improved performance.

Injury differences

With increased ankle flexion there is an increased load placed on the Achilles tendon and possibly the tensor  fascia. It is likely barefoot running will initially increase the risk of Achilles tendonitis and tears to the soleus muscle

Minimalist and barefoot running has been suggested (small studies) to cause higher rates of tarsal (midfoot) loading and possible stress fractures

With increased anterior knee movement due to increase early dorsi flexion there will be higher forces placed on the patella tendon throughout the gait, whether this impacts patella tendinitis and arthritic wear due to shearing forces is not known

Running in a motion control shoe with larger heel drops may lead to injuries related to overstriding, such as lower back and hip conditions. Studies of supportive shoes shoe higher ground reaction forces and possible links have been reported for anterior shin splints. There is also a greater joint load or stiffness at the knee joint as opposed to the ankle and foot joint with barefoot running. This increases loading of the tibial plateau of the knee which would be expected to increase wear at the cartilage of the knee

As mentioned above the adaption to barefoot running is the unknown variable. Increasing barefoot running distances rapidly will most likely result in injury. It isn’t possible for the body to adapt to new forces in the space of weeks. Months or years are likely to be required for tendons and bones to respond completely to the new demands.

Barefoot running and athletic performance

Shoe weight has been shown to significantly increase running economy at a suggested rate of 1% per additional 100 grams (Frederick, 1984, Franz et al, 2012, Divert et al, 2008). This translates to a 2.4 seconds per km per 100 grams benefit. With the average shoe weight being just over 200 grams this gives a significant performance benefit of around 50 seconds over a 10km race. Some studies though have failed to show the expected level of improvement in running ecomomy that would be expected due to changes in foot mass (Franz et al, 2012, Squadrone and Gallozzi, 2009). Warne (2014), showed when given time to adapt barefoot running was indeed significantly more efficient than shod suggesting skill acquisition and possible changes in the toughness of the feet may be required to handle the barefoot running. No time trial data of athletes wearing shoes compared to barefoot exists. Most likely on grass barefoot running would provide minimal improvements. But then traction would be required and this would require shoes. On hard surface the avoidance of pain due to impact likely prevents maximal running speeds being reached. This pain avoidence is the probable reason why stride frequency increases with barefoot running. More strides equals less ground contact loads. Tung (et al, 2012) found a significant improvement in running economy when comparing barefoot running on a 10mm foam cushioned treadmill compared to running on a standard treadmill. This difference would most likely be greater comparing cement to 10mm foam due to the small cushioning element of the treadmill. This fact is the predominate reason why no professional athletes are undertaking barefoot running. If you could run with this 10mm foam attached to your feet then... oh wait, that would be running in light cushioned shoes. Racing flats reduce shoe weight to almost 100 grams whilst providing the small amount of cushioning required. This cushioning allows the runner to place greater forces on the ground without any negative side effects. Without years of adaption it is not possible to run on hard surfaces at high speeds barefoot. Look at any other animal who engages in running on hard surfaces, their paws are thick and padded and most likely no wear near as tactile as human feet. If this same animal spends large amounts of time on rocky ground you’ll most likely find they indeed have hooves

Summary – The barefoot debate

Barefoot running modifies technique increase ankle and foot loads whilst lowering chosen stride frequency. There is an improvement in running economy that is associated with the reduced weight of the lower leg. This improvement fails to translate into improved running performance due to the negative effects of hard surface impacts on running speed. With the light design and added cushioning of racing flats it is unlikely barefoot running can rival shoes for high end performance. In regards to injuries barefoot running may reduce peak impact loads at the knees and shins and decrease forces at the hips and lower back. There will be increased loading on the foot, plantar fascia, Achilles tendon and lower leg muscles. It is likely different injuries rather than less injuries will occur with barefoot running as opposed to shod. Changing to a barefoot gait must be performed slowly as tendons and bones adapt over long periods. Some foot structures may not adapt to barefoot running and will find a shoe there risk of injury. In most people performance will most likely decrease due to the inability to perform high training loads on hard surfaces  

References

Cavanagh, PETER R., and KEITH R. Williams. "The effect of stride length variation on oxygen uptake during distance running." Medicine and Science in Sports and Exercise 14.1 (1981): 30-35

De Wit, Brigit, Dirk De Clercq, and Peter Aerts. "Biomechanical analysis of the stance phase during barefoot and shod running." Journal of biomechanics 33.3 (2000): 269-278.

Divert, C., et al. "A. Belli1 Mechanical Comparison of Barefoot and Shod Running." Int J Sports Med 26 (2005): 593-598

Divert, C., et al. "Barefoot-shod running differences: shoe or mass effect?."International journal of sports medicine 29.06 (2008): 512-518.

Franz, Jason R., Corbyn M. Wierzbinski, and Rodger Kram. "Metabolic cost of running barefoot versus shod: is lighter better." Med Sci Sports Exerc 44.8 (2012): 1519-25

Frederick, E. C. "Physiological and ergonomics factors in running shoe design."Applied ergonomics 15.4 (1984): 281-287

Högberg, Paul. "How do stride length and stride frequency influence the energy-output during running?." European Journal of Applied Physiology and Occupational Physiology 14.6 (1952): 437-441.

Rao, Udaya Bhaskara, and Benjamin Joseph. "The influence of footwear on the prevalence of flat foot. A survey of 2300 children." Journal of Bone & Joint Surgery, British Volume 74.4 (1992): 525-527.

Sachithanandam, V., and Benjamin Joseph. "The influence of footwear on the prevalence of flat foot. A survey of 1846 skeletally mature persons." Journal of Bone & Joint Surgery, British Volume 77.2 (1995): 254-257.

Squadrone, R., and C. Gallozzi. "Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners." J Sports Med Phys Fitness 49.1 (2009): 6-13.

Tung, K., J. Franz, and Rodger Kram. "A test of the metabolic cost of cushioning hypothesis in barefoot and shod running." American Society of Biomechanics Annual Meeting. Gainesville, FL. 2012

Warne, J. P., and G. D. Warrington. "Four‐week habituation to simulated barefoot running improves running economy when compared with shod running."Scandinavian journal of medicine & science in sports 24.3 (2014): 563-568