# Morphology-Related Foot Function Analysis: Implications for Jumping and Running
## 4 Discussion
Among all the barefoot and shot participants, biomechanical data for the forefoot strike barefoot running, and rearfoot strike shed running were included in this study. Barefoot running was reported to be different to minimalist, racing, or regular shoe conditions in a previous biomechanical study of experienced runners [38]. The extrinsic muscles of the foot presented reduced muscular activity during barefoot running, for instance, peroneus longus [39; 40]. Other controversial opinions were proposed between the minimalist and barefoot running when compared to traditional shoe running [41; 42]. This study focused on the biomechanics from the forefoot and toe morphology, thus, shed running from the barefoot group and barefoot running from the shot group were not performed during the test, which was aimed to reduce the acute response of altering to shed (for the barefoot group) or barefoot (for the shot group) running. During the running test, each participant performed running at a comfortable speed so as to present natural running biomechanics [7; 43]. The results indicated significant differences in strike length, strike time, and contact time between the shot and barefoot groups, which are consistent with previous studies [2; 7; 8]. In previous barefoot running studies, the barefoot group was observed to reduce these spatiotemporal parameters [8; 44; 45]. The stride time of the barefoot group was significantly less than the shot [46]. The running performance of the barefoot group was characterized by landing on the forefoot, and the ankle changed from plantar flexion to dorsiflexion in the sagittal plane, which contributed to the greater dorsiflexion angle during the stance. The shot running resulted in landing with the rearfoot, and the ankle in the dorsiflexion position, which could explain the ankle angle difference as the foot strikes. Different foot strike patterns could be a reason for the strike time differences observed [8]. The observed knee contact flexion angle and peak flexion angle difference of shot running in this study may be a compensatory movement (with larger sagittal knee ROM), resulting from the previously established greater knee impact while rearfoot shot running [9; 45; 47]. As shown by the hip flexion angle, the contact flexion angle was larger than that of barefoot running, and this could explain the increased stride length of shod running and, although not significant, an about hip flexion-extension ROM was observed. In terms of the plantar pressure distribution, the barefoot group showed smaller peak pressure and pressure-time integral than the shod group in the rearfoot. This may have been caused by the rear foot landing during shod running, which results in a larger contact area in MR and LR. The difference in contact area in MM may be related to the uppers and soles of the footwear while shod running. Owing to the forefoot strike of barefoot running, the larger peak pressure and pressure time integral to the LM and LF may result from the landing impact. This finding could explain the previously reported forefoot metatarsus fatigue injury due to the repetitive impact and lack of cushioning protection from footwear [1; 24]. The hallux showed an increased peak pressure and pressure-time integral during barefoot running, and, while not significant, this was also observed for the contact area. This may result from the active gripping motion of the separate hallux \"leverage function\" expanding the push-off supporting area (fulcrum) [1; 36]. Thus, less loading was found in the MF compared with shod running, which presented greater MF loading and smaller H loading. The greater ankle ROM in the coronal plane and peak angle while pushing off may be kinematic evidence for the active toes function related to the morphological differences in this study. As reported, the function of the remaining toes may also be used for balance and stability control under static and dynamic conditions [48], and it may also be useful during running and jumping performances.