[Tony Kauth is a senior studying Exercise and Sport Science at the University of Wisconsin-La Crosse, and an Applied Sport Science Intern at Athletic Lab.]
A simple Google search of the phrase ‘barefoot running’ will provide numerous results, often leaving a reader confused with where to begin and what to believe. Aside from that, every coach, athlete, sport scientist, physical therapist, and running enthusiast will likely have a very strong opinion on certain aspects of the topic. With opposing views easily available, the purpose of this article is to take a critical look into some of the research on barefoot running, and specifically, its potential utilization as a means of injury prevention for endurance runners.
Most endurance runners have experienced performance-related injury to some extent during their career. While misalignment due to foot insufficiency, high Q-angle, lower extremity muscle stiffness, and genu varum may contribute up to 40% of injuries among runners (Lysholm & Wiklander, 1987), these biomechanical mechanisms may be correctable. In attempts to correct for these insufficiencies, endurance runners are often prescribed recovery-type runs barefoot on grass. Recovery runs typically consist of 10-15 minute strides on grass or artificial turf at the end of a training session, 2-3 times per week. Does implementing this training stimulate the musculature enough to correct for any of the biomechanical deficiencies listed above? If so, does its implementation cause any other problems?
A Long-Term Approach:
Many barefoot running advocates (be it exclusively barefoot or those who believe in its importance to incorporate with shod training like Jason Fitzgerald) advocate for a very gradual transition, often over the duration of a year. Studies that have investigated the effects of muscle activation (which when increased would correlate to increases in hypertrophy) are often very short. What is considered to be a long-term study by da Silva Azevedo et al (2016), in which subjects completed a 16-week progression to barefoot running protocol, is still short in comparison to the 52 weeks in a year. It is possible that while scientific evidence currently may not strongly support greater muscle activation, it could be due to lack of the duration of monitoring. In this case, advocates that are in favor of incorporating barefoot recovery runs within shod training may be a better source of evidence as they have often been utilizing this technique for many years and personally notice improvements in muscle strength (Kelly et al, 2016). It’s always important to consider what is being done outside the lab.
Strengthening Foot Musculature:
Another point to consider is the process by which any beneficial muscle hypertrophy would occur as the result of barefoot running. Studies like Fleming et al (2015) and da Silva Azevedo et al (2016), have found that barefoot running results in decreased muscle activation in anterior shank muscles, and increased activation in posterior shank muscles in inexperienced barefoot runners. This change in motor recruitment is likely due to the biomechanical alterations that occur because of the different foot strike patterns while barefoot. While this may suggest that barefoot training can increase posterior shank muscle hypertrophy, the process of doing so (through alteration of foot strike motor patterns) may not be beneficial if the athlete is primarily training and competing shod. Training motor patterns that are not the athlete’s primary means of locomotion could increase injury risk when the recruitment complexes needed for shod running have been slightly altered as the result of barefoot running.
Posture and Running Efficiency:
Another popular argument for barefoot running is the improvement of running posture and its effect on foot strike and general running efficiency. With any technical movement such as running posture and efficiency, time for chronic adaptation leading to noticeable improvement may require greater than 30-45 minutes of work per week. Especially considering that it is only 5%-10% of the athlete’s total time running. Technique in any athletic movement requires a great time commitment in order to elicit any improvement (Israetel, 2015). While endurance runners often work on the technical movements of their sport more within their shod training, to be seeking transferable improvement from barefoot training seems unlikely with such a short amount of time dedicated to it.
It is also important to consider the psychological implication that barefoot running may provide. While the 5%-10% dedication of training time to barefoot running may not be long enough to improve running efficiency, it may be long enough effect proprioceptive mechanisms. Even low amounts of barefoot running may create a placebo-like effect where athletes have proprioceptive changes in biomechanics and running posture as a result of a pure belief that it is beneficial. Studies have shown that non-structural, external touch can increase proprioception in the lower leg (Bae, 2017) which may also occur through cutaneous nerve excitation when shod runners experience the external touch of grass or artificial turf against their skin. However, the external stimulus of the grass touching the skin may need to be present for proprioceptive changes to occur, and removing it by putting shoes back on, could negate any effects.
Injury Risk and Considerations:
In habitually shod runners, introducing barefoot running does initially increase the rate at which load is applied to the athlete’s body, resulting in greater impact forces experienced by the athlete and increased plantar pressure. With such occurrences, the introduction of barefoot running may increase the athlete’s injury risk; however, a long-term progressive transition to running barefoot may actually reduce impact forces and help to reduce injury risk (da Silva Azevedo et al, 2016; Bergstra et al, 2015).
Although biomechanical insufficiencies result in about 40% of injuries in endurance runners, it is important to understand that the other 60% comes primarily from training itself; shod or barefoot does not play a role (Lysholm et al, 1987). Incorporating barefoot running (or not) for injury prevention means that athletes will still likely experience injuries. This training is only another factor to consider in a much wider spectrum of keeping athletes healthy. When a coach or athlete is considering the implementation of barefoot running as a means of injury prevention, Jason Fitzgerald may have explained it best; that it is important to be cautious and to do what works for you (or your athlete). The end goal is to make a new personal record (PR), and each athlete needs to experiment to learn how their body reacts to different stimuli, and determine what will make them the most successful. If you’re a coach and enjoy incorporating barefoot running into training, continue to do so. If you haven’t implemented it, then perhaps you should try. Either way, pay attention to how your athletes respond both objectively through performances and subjectively based on what they say. Then adjust training to incorporate more, or less volume if you need to so they can make those PRs.
Bae, Y. S. (2017). Effects of spiral taping on proprioception in subjects with unilateral functional ankle instability. Journal of Physical Therapy Science. 29(1), 106-108. Retrieved from https://www.ncbi.nlm.nih.gov/
Bergstra, S. A., Kluitenberg, B., Dekker, R., Bredeweg, S. W., Postema, K., Van den Heuvel, E. R., Hijmans, J. M., & Sobhani, S. (July 2015). Running with a minimalist shoe increases plantar pressure in the forefoot region of healthy female runners. Journal of Science and Medicine in Sport. 18(4), 463-468. Retrieved from https://www.ncbi.nlm.nih.gov/
da Silva Azevedo, A. P., Mezêncio, B., Amadio, A. C., & Serrão, J. C. (2016). 16 weeks of progressive barefoot running training changes impact force and muscle activation in habitual shod runners. PLoS one, 11(12). Retrieved from https://www.ncbi.nlm.nih.gov/
Fitzgerald, J., & Gaudette, J. The importance of strength training and how to easily incorporate it into your training schedule. Runners Connect Podcast. Retrieved from https://runnersconnect.net/
Fleming, N., Walters, J., Grounds, J., Fife, L., & Finch, A. (August 2015). Acute response to barefoot running in habitually shod males. Human Movement Science, 42, 27-37. Retrieved from https://www.sciencedirect.com/
Israetel, M. (2 March 2015). Training frequency; a brief discussion. Renaissance Periodization Youtube Channel. Retrieved from https://www.youtube.com/watch?
Kelly, L. A., Lichtwark, G. A., Farris, D. J., & Cresswell, A. (June 2016). Shoes alter the spring-like function of the human foot during running. Journal of the Royal Society Interface, 13(119). Retrieved from https://www.ncbi.nlm.nih.gov/
Lysholm, J., & Wiklander, J. (1987). Injuries in runners. The American Journal of Sports Medicine, 15(2).