###### Abstract  
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.  
biomechanical phenomena; running; sports +
Footnote †: journal: _Sciences_  
Brief ReportBiosignals by In-Shoe Plantar Pressure Sensors on Different Hardness Mats during Running: A Cross-Over Study  
[PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] Bioignals by In-Shoe Plantar Pressure Sensors on Different Hardness Mats during Running: A Cross-Over Study  
[PERSON], [PERSON], S.  
Thus, running biomechanics may vary depending on the mechanical behavior exhibited by different surface hardnesses [3,4] and shoe materials [5]. In addition, plantar pressure and force parameters presented adequate within- and between-day repeatability during running for analyzing gait patterns and changes on different surfaces [6]. Concretely, peak plantar pressures and maximum forces in runners presented a clear relationship between different surface hardnesses and their impact on the lower limbs [3,4].  
More than 30 years ago, the on-target use of plantar pressure distribution on flexible mats was claimed as a key evaluation in traumatology, sports orthopedics and adjacent overlapping fields. Dynamic measurements for pressure distribution on a flexible mat as a capacitor may provide valuable findings on human locomotor system stress, injury prevention and sport performance optimization [7].  
Nowadays, in-shoe plantar pressure sensors have been used as the preferred measurement method for determining maximum forces and peak pressures to study the effects of running on several surfaces with different hardness [3,4]. The relationship between jumping modality performance and sprint parameters in sprinters was determined using in-shoe sensors [8]. In addition, footfall dynamics was evaluated in racewalkers and barefoot runners on different surfaces [9]. Although the effects of running on plantar pressures have been detailed on several surfaces with different hardness [3,4], there is a lack of studies assessing the mechanical behavior analysis by in-shoe plantar pressure sensors on mats with different hardness during running. We hypothesized that mats with greater hardness could present higher maximum forces and peak pressures during running. Thus, the aim of the present study was to assess and compare in-shoe maximum forces and peak plantar pressures on mats of three different hardnesses--hard, soft and air chamber mats--during running.