6 This has been shown to decrease vertical loading rate compared to shod runners.7 and 8 It has also been shown that compared to barefoot running, shod running elevates torques at the knee and hip joints, over and above what is expected through adaptations in stride length and cadence.6 Modern-day running shoes increase joint torques throughout the lower extremity. This increase is likely caused by in part the elevated heel and increased material under the medial aspect of the foot. Kerrigan et al.6 found an increase

in knee flexion torque with running shoes. These increases could potentially elevate the demand from the quadriceps muscle, increase strain through the patella tendon, and therefore increase pressure Akt inhibitor SAHA HDAC mouse across the patellofemoral joint, a common site of running injury.6 The study also found an increase in the knee varus torque, which is hypothesized to lead to greater compression forces in the medial compartment of the knee, a common area for osteoarthritis. Traditional running shoes also increased the hip internal rotation torque significantly.6 However, there is also evidence of lower ankle joint torques during heel striking in traditional running shoes compared to midfoot and forefoot striking in minimalist shoes.13 The links between the amount of torque or loading rate and injury have not been fully explored or elucidated. However, the existing studies

show that traditional shoe construction alters loading in a manner that increases injury risk. Interestingly, the injury that demonstrated the greatest improvement following starting found a barefoot running program was at the knee. This is significant as knee injuries are the most common injury runners sustain. Runners in this survey also had their

previous foot (19%), ankle (17%), hip (14%), and low back (14%) injuries improve after starting barefoot running. In fact, a large majority (64%) of runners in this study experienced no new injuries after starting barefoot running. Habitual barefoot running has been shown to be associated with lower vertical loading rates. Loading rates and impact forces with foot strike are thought to contribute to the high incidence of running-related injuries such as tibial stress fractures and plantar fasciitis.2, 14 and 15 The initial impact force, and associated vertical loading rate, has been linked to stress fractures in the lower limbs.16 Foot strike is also an important factor in forces generated during running in barefoot versus shod running. Unfortunately, in this survey study, questions pertaining to foot strike were not asked of the participants, nor could it be accurately assessed. Habitually shod runners have been shown to tend to continue to heel strike when barefoot running, while habitually barefoot runners tend to forefoot or mid-foot strike.7 Contact style is just one of the many factors that influence lower extremity mechanics.