Barefoot Versus Shod Running: Which Is Best?
The most likely explanation for the consistently shortened stride in barefoot running is that, without the protection of a shoe on their feet, most barefoot runners will tend to avoid having their plantar heel impact the ground at foot strike.14 In order to avoid heel strike, barefoot runners will position their ankles in a more plantarflexed position at foot strike by pre-activating their gastrocnemius and soleus muscles before foot strike.14,16,18-21 In support of the idea that barefoot runners tend to avoid heel strike to avoid plantar heel injury, measurement of the heel fat pad deformation during barefoot and shod running demonstrated that the maximal deformation of the heel fat pad was 60.5 percent in barefoot running whereas in shod running, the heel fat pad only deformed 35.5 percent. This study showed that shoes offer significant supportive function to the heel fat pad.22
Even though heel striking runners make up between 75 and 89 percent of runners, recent research may suggest that since most barefoot runners avoid heel strike, they also may be able to reduce their impact load by avoiding the initial loading peak that occurs in the majority of runners who heel strike.23-26
Unfortunately, the literature is undecided as to whether barefoot or shod running is better at decreasing the vertical loading rate (VLR) from ground reaction force (GRF) at foot strike. Even though a few studies have shown that the vertical loading rate is less in barefoot running, other studies have shown that barefoot running actually increases the vertical loading rate.14,22,23,28-31 In addition, some studies have shown that barefoot running reduces the magnitude of the ground reaction force impact peak while other studies show that barefoot running increases the magnitude of the impact peak.14-16,19,23,27
The question of whether barefoot running or shod running is better at reducing the impact loads of running may be an important one since there is some suggestion that certain running injuries, such as tibial stress fractures, may be more prevalent in female runners who exhibit increased vertical loading rate during running.32 However, prospective research has also found that people with a higher vertical loading rate had significantly fewer running-related injuries than those people who had a lower vertical loading rate.33
Other research findings, which weaken the argument that impact shock causes running injuries, are that shock-absorbing insoles have not reduced the incidence of stress fractures and running on hard surfaces did not result in any increase in running-related injuries in comparison to running on softer surfaces.34-36 In his latest book, Benno Nigg, Dr.sc.nat., Dr.h.c, one of the world’s leading researchers in foot and lower extremity biomechanics, offered the following opinion on the importance of impact forces in causing running injuries: “Currently, there is no conclusive evidence that impact forces during heel-toe running are responsible for development of running-related injuries.”37
Does Barefoot Running Offer Metabolic Advantages?
Still, barefoot running does seem to have one clear benefit over running in shoes: running while barefoot is more metabolically efficient than shod running. Research has shown that running in shoes increases the oxygen uptake versus barefoot running and also increases the perceived exertion and heart rate versus barefoot running.16,38 The most likely explanation for the increased metabolic efficiency of barefoot running is that the added mass of the shoe creates extra energy cost for runners in order to accelerate their lower extremity forward with each running stride.39