Running is a popular form of exercise because of the positive health benefits and the fact that it can be done virtually anywhere without any special equipment. Many patients with patellofemoral pain want to continue running. As health care providers, we need to educate these runners on the risks as well as the benefits of continuing to run.
Different running styles, including chi running, barefoot running and evolution running, have been developed to eliminate the initial heel strike and to promote the forefoot strike upon initial impact. No definitive conclusions can be made that these alterations in strike patterns prevent or reduce injury. However, several studies have shown that elimination of heel strike results in a significant reduction in ground reaction forces, stride length and ground contact time. These changes can have a positive effect on the patellofemoral joint.
Robin V. West
Before the invention of running shoes in the 1970s, people ran in either no shoes or minimal footwear. The author of Born to Run, Christopher Macdougall, was credited with started the barefoot running trend following its publication in 2009. Although barefoot running has become more popular in recent years, many competitive runners have run successfully barefoot prior to the book’s publication. The popularity of barefoot running has probably increased recently as more shoe companies are designing minimalist shoes to mimic barefoot running.
Biomechanical differences have been observed when comparing barefoot and shod runners. Barefoot running is associated with increased foot and ankle plantarflexion, resulting in decreased peak vertical ground reaction forces, shorter stride length and contact time, and a higher stride frequency. Barefoot running has also shown a significant decrease in peak PF joint stress and reaction forces in multiple studies.
Excessive hip adduction (HADD), hip internal rotation (HIR) and contralateral pelvic drop (CLPD) during running are kinematic variables that increase patellofemoral pain in women. Using 3-D gait analysis, 23 habitually shod, uninjured female recreational running athletes were studies while running with and without shoes. The barefoot runners showed higher step rates, decreased rear-foot strike and increased forefoot running, and lower HADD, HIR and CLPD when compared to shod runners at both initial contact and 10% stance.
The study above was done in asymptomatic runners. So, does forefoot or midfoot running improve symptomatic runners with knee pain? Also, do you have to run barefoot or can you just alter your foot strike position? A small cases series addressed both of these questions. Three runners with patellofemoral pain were evaluated who initially presented with a rearfoot strike pattern. They underwent eight sessions of landing pattern modification using real-time audio feedback from a force sensor placed within the shoe. Ground reaction forces, patellofemoral pain and running performance were assessed. The landing pattern of runners was successfully changed from a rearfoot to a non-rearfoot strike pattern after training. The vertical impact peak and rates of loading, as well as the patellofemoral pain symptoms and functional limitations were reduced. These runners improved their symptoms by only addressing their foot strike pattern and not by running barefoot.
Another study evaluated 22 highly trained runners during over-ground running while barefoot and in a three shod conditions (minimalist, racing flat, a regular shoe). They found that barefoot running resulted in significant differences between all shoes. There was no difference when comparing the three shoe conditions. Barefoot running demonstrated less knee flexion during midstance, an 11% decrease in peak internal knee extension and abduction moments and a 24% decrease in negative work done at the knee compared to shod conditions. The ankle demonstrated less dorsiflexion, a 14% increase in peak power generation and a 19% increase in the positive work done during barefoot running.
In conclusion, barefoot running significantly reduces the ground reaction forces, stride length and ground contact time and increases the step rate. The increased step rate results in a reduced knee extension moment and knee flexion angle during the stance phase, which substantially diminishes peak patellofemoral joint contact forces.
Barefoot running is not the only way to achieve the biomechanical benefits. Barefoot running leads to more forefoot initial contact, but shod runners can also modify their foot position (forefoot or midfoot) at contact and get the same benefits.
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Robin V. West, MD, is the Medical Director, Sports Medicine, Inova Health System in Falls Church, Va.; email: Robin.West@inova.org.
Disclosure: West has no relevant financial disclosures.