Time and frequency domain analysis of ground reaction force in highly cushioned shoes with a carbon-fiber plate

The running related injury rate has been reported as high as 37%-56% and keeps consistent to recently years (Mechelen et al. 1992; Messier et al. 2018). Although multifactorial factors can increase the risk of running related injuries, impact-related ground reaction force (GRF) variables, which include peak value of vertical GRF, vertical loading rate, may play a key role in the cause of injury. (Messier et al. 2018; Caleb et al. 2020). Accordingly, the use of cushioned or shock-absorbing shoes has been suggested since these shoes may reduce the impact forces during running (Rome et al. 2008). However, the effectiveness of shoes in reducing impact force remains controversial in the literature. Recently, highly cushioned shoes with a carbonfiber plate have received increasing attention from scholars and practitioners. This new advanced running shoes may dramatically reduce the impact force and the vertical impact peak may be visually absent in the time-domain. However, a study showed that although a distinctive vertical impact peak may not be visible, frequencies representative of a significant vertical impact are present. (Gruber et al. 2017). Therefore, it remains a question if the highly cushioned shoes could change the frequency content of the GRF when the vertical impact peak is not visible in the time domain. Purpose of the study