# Morphology-Related Foot Function Analysis: Implications for Jumping and Running
## 4 Discussion  
This study aimed to analyze foot morphology-related jumping and running biomechanics and evaluate any potential functional differences. Participants in this study were from different parts of Asia, with a barefoot group from Indian ethnicity and a shot group from Chinese ethnicity. The main findings were that, (i) during the push-off and landing phases of the vertical jump, the separate hallmark of barefoot individuals shared loading from the metataralsals, and thus expanded the loading concentrated region; (ii) during the push-off phase of running, there were plantar pressure differences in the hallmark and forefoot of barefoot individuals compared with shed individuals; (iii) barefoot individuals with separate toes presented a flexible range of motion, particularly in the coronal plane of the ankle, sagittal plane of the knee, and horizontal plane of the hip. Hallux angle has been reported to be different among populations of different ethnicities [11]. However, few studies have focused on the minimal distance between the hallmark and the interphalangeal joint of the second toe. Compared with results of our previous study [4], barefoot groups in this study had a larger distance and smaller hallux angle, while the shed group had a larger hallux angle and smaller distance. It may be concluded that the barefoot group had more flexible hallux than the  
Figure 3: Foot pressure of barefoot and shed running. Medial rearfoot (MR), lateral rearfoot (LR), medial midfoot (MM), lateral midfoot (LM), medial forefoot (MF), lateral forefoot (LF), hallux (H), and other toes (OT). * indicates significance, \(p<0.05\). -shot group [1; 3; 36]. [PERSON] et al. [36] reported that if the separate hallux has ambulatory and prehensile functions, it could work fundamentally the same way as the fingers. However, wearing shoes may block these prehensile and separate functions of the toes, due to the sharp-headed or ill-fitted space restrictions [3; 6; 14]. The hallux angle and minimal distance are the basis of the morphological differences for the vertical jumping and running test in this study. Results from the vertical jump test indicated that the hallux presented larger plantar loading in the barefoot group compared with the shot group (Figure 1). During the push-off phase, the plantar loading of the barefoot group was larger under the hallux, while the pressure of the shot group was larger under the medial forefoot and central forefoot. The same pressure time integrals were presented in these anatomical regions, which may imply that the hallux of the barefoot group was used predominantly, while the forefoot of shot group was used primarily. Moreover, the peak pressure of the barefoot reduced in the forefoot regions while landing. This suggests that the gripping function of the hallux could firm and expand the supporting base during the push-off and landing phases by the separate toes [3; 36]. In addition, large loading under the hallux could reduce the impact force to the forefoot [24]. Previous research has reported that excessive loading under the metatarsal head area (forefoot) would lead to forefoot injuries [7]. These findings imply that the foot morphology related to toe gripping functions may have a possible link with forefoot metatarsal stress injuries. However, this study did not investigate the injury risks between the two population groups. The jumping height showed no significance, which implies that the morphological differences may not be linked with jumping performance, or there may be a limitation in the akimbo position. Further research is needed and should focus on jumping performance via comprehensive kinematic analysis. Research pertaining to habitually barefoot and shot people has received increased attention in recent years. Different ethnicities [4; 5; 24], pathological factors [37], and different forms of sport participation [10] could influence foot morphological differences.