This is an excerpt from Running Mechanics and Gait Analysis With Online Video by Reed Ferber & Shari Macdonald.
Barefoot running, or running in a minimalist shoe, has received increasing attention within the popular media over the past several years. However, one must first realize that barefoot running is not new to elite runners, with Abebe Bikila winning gold in the 1960 Olympic marathon while running barefoot and Zola Budd setting the world record for the 5000 m at the 1984 Olympic games. The first research study published was in 1987 (Robbins and Hanna 1987). Since then, multiple studies have been conducted to understand the potential alterations in running mechanics when running barefoot. However, it is important to note that, to date, there is no research that either supports or refutes the injury preventative aspects of running barefoot that marketing campaigns and advertisements promote. There is only research to confirm that running barefoot is different than running shod.
While looking at the effects of running in shoes compared with running barefoot, it has been reported that running barefoot, or even running with a forefoot strike as opposed to a rearfoot strike, results in decreased stride length; increased stride rate; decreased range of motion at the ankle, knee, and hips; and a more plantar flexed ankle position at ground contact (De Wit et al. 2000; Divert et al. 2005; Lieberman et al. 2010). Moreover, Kerrigan et al. (2009) reported a 54% decrease in the hip rotational forces, a 36% decrease in knee flexion forces, and a 38% decrease in frontal plane knee forces when running barefoot compared with running in shoes.
While these results appear impressive, a closer inspection reveals that there is no clear answer about whether barefoot running is injury preventative or causative. For example, by decreasing stride length, and increasing stride rate, more steps are taken per kilometer. For the average runner running a marathon, this would result in 1,280 more steps to finish the race but only two minutes less of total foot contact time over a 3 hr, 20 min time compared to running shod. The increased numbers of steps and increased repetitions of maximum vertical loading when running barefoot (or with a forefoot strike pattern) could be injury-causative. On the other hand, 36% to 54% less force at the hip and knees for every step could be injury-preventative. Moreover, based on mechanical properties of the Achilles tendon (Konsgaard et al. 2011) and when considering that a forefoot strike pattern forces the heel downwards shortly after contact with the ground (Kerrigan et al. 2009; Lieberman et al. 2010), each step taken when running barefoot results in 59% of the force needed to rupture the Achilles tendon. The increased tensile loading of the Achilles tendon could result in tendinopathy, a gastrocnemius, or soleus muscle strain.
In summary, while research has been done on how barefoot running alters an individual's mechanical patterns and joint loading, no studies have been conducted on whether injury rates or specific injuries are reduced compared with shod running. Considering the complexity of the etiology of running injuries, changing one parameter such as footwear or even eliminating shoes altogether and completely altering the mechanical pattern cannot eliminate the occurrence or potential for musculoskeletal injuries. In fact, rapid alterations in one kinematic running pattern place a runner at risk for injury. Finally, considering that the magnitude of force applied to the system, a runner's mass, does not substantially change whether barefoot or shod, the changes in mechanics attributed to running barefoot or running with a forefoot strike would simply result in the impact force being redistributed elsewhere within the body. Thus, while barefoot running may result in a reduction of some injuries, such as to the knee and hip, we are likely to see an increase in other injuries, such as to the metatarsals, plantar fascia, and Achilles tendon. Future research will help answer these questions.