Biosignals by In-Shoe Plantar Pressure Sensors on Different Hardness Mats during Running: A Cross-Over Study

Although the effects of running on plantar pressures have been detailed on several surfaces with different hardness, there is a lack of studies assessing the mechanical behavior analysis by in-shoe plantar pressure sensors on different hardness mats during running. The aim of the present study was to determine in-shoe maximum forces and peak plantar pressures on mats with different hardness, such as hard, soft and air chamber mats, during running. A cross-over study was carried out including 36 amateur runners from a sport center. The maximum force and peak pressures of the foot plantar region were analyzed on three different mat hardnesses —soft and hard polyurethane foam mats and air chamber mats—by in-shoe instrumented insoles. Running on soft polyurethane foam mats presented reduced maximum forces in the whole plantar region and mainly peak pressures in the anterior part of the foot plantar region, such as the toes and first to fourth metatarsal heads, compared to hard polyurethane foam and air chamber mats. The peak pressure in the fifth metatarsal head was specifically reduced during running on soft compared to hard polyurethane foam mats, and running on these soft mats decreased calcaneus peak pressures compared to running on air chamber mats. Running on air chamber mats increased peak plantar pressures in the first metatarsal head compared to running on hard polyurethane foam mats. The mechanical behavior of mats of different hardness could be used to adjust the degree of impact on plantar pressures to determine the most appropriate materials and hardness for running.