Effect of carbon plate inserted in trail running shoes on foot and shank acceleration at different slopes

Trail running has become popular and is characterized by running on rough terrain with positive and negative elevation changes throughout the course. Downhill running is associated with increased eccentric muscle contraction and increased peak tibial acceleration (Chu and Caldwell, 2004), which has been correlated with tibial stress fractures in runners (Milner et al., 2006). Although biomechanical differences during downhill running have been described, these effects have been mainly reported on treadmills, where the subjects typically run at a controlled speed. However, this is not a reality in trail running as the subjects change their pace due to various uphill and downhill slopes. To address this issue and to provide “realworld” data, inertial measurement units (IMUs) have been employed. Indeed, the literature has encouraged the use of IMU sensors to perform biomechanical analysis of running patterns in the natural environment (Reenalda et al., 2016). To improve running performance, running shoe technology such as the incorporation of increased longitudinal bending stiffness (LBS) and curved carbon-fiber plates has been adopted by the footwear industry. Although a carbon plate seemed not to influence the tibial acceleration in a previous study, this was conducted on the treadmill at a constant speed and only 1% of inclination (Kiesewetter et al., 2022). Purpose of the study