Comparison of Impact Force and Muscle Activity of Barefoot and Shod Running

In recent years, running has seen a very significant increase in participants. Since 2000, the number of athletes completing half marathons has increased to 1.1 million in the US, representing a 131 percent increase as of 2011. It has been suggested that eight out of ten runners are injured every year. According to Christopher McDougall, the Tarahumara tribe in Mexico ran for many days on end without injury with minimum covering and protection on their feet. The objective of this study was to answer the research question whether barefoot running is superior to shod running by comparing impact force and muscle activity of barefoot and shod running. Six individuals with no prior experience of barefoot running were tested using a combination of force plate, electromyography (EMG), and motion capture. Impact force was measured by the force plate and normalized against the body weight. Muscle activities of the medial and lateral gastrocnemius were obtained through a wireless EMG system. The motion capture system allowed us to analyze the strike pattern of the foot. Each individual completed a trial of barefoot running and a trial of shod running. Paired student t-tests indicated that impact force of barefoot running was significantly less than that of shod running. The muscle activity of the medial gastrocnemius while barefoot running was less by a marginally significant amount than that of shod running. The lateral gastrocnemius did not show significant differences of muscle activity between barefoot and shod running. Most of the individuals had a heel landing strike pattern for both barefoot and shod running. Our research results have indicated that there is significantly less impact force when running barefoot, compared to shod running. Such a reduction is more evident in a toe strike pattern than in a heel strike pattern. If someone wished to adopt barefoot running, it is vital that the individual needs a personal trainer to safely modify the running gait from a heel strike to a toe strike pattern. If barefoot running is performed with a heel strike pattern, there is an increased risk of injury associated with the repetitive impact force. Table 1. Impact force and muscle activity from barefoot and shod running Barefoot running Shod running p-value Impact force (body weight) 1.37±0.15 1.75±0.30 0.027* EMG of M Gastrocnemius (mV) 4.10±3.17 4.83±3.5 0.058 EMG of L Gastrocnemius (mV) 2.74±0.995 2.87±0.93 0.678