Research On Stress Response Of Navicular Height And The Influence Of Landing And Buffering

Purposes:In this paper, the biomechanical response of the human foot with different loads and damage mechanisms may be brought, based on the analysis of the navicular height. To provide the theoretical and experimental reference for the basic research and rehabilitation of foot injury, the functional information of the dynamic load and functional behavior of foot during exercise were explored.Methods : Twenty-three male healthy subjects were randomly selected and screened, they completed the navicular drop test and single landing from 15cm-high and 30cm-high platform with zero initial speed. Biomechanical indexes acquisition were synchronized by high-speed cameras, Vicon-MX with infrared motion capture system and Kistler force platform, such as different directions of peak ground reaction force and the lower limb angles within100 ms before landing, the groud-contact time of the foot, the time of the foot deformation. All the data were dealt with Microsoft Excel 2010 and SPSS19.0 statistical software.Results:①The maximum force by single landing from 15cm-high and 30cm-high equivalent to 3-time or 4-time body weight(BW), respectively. Below 4BW load, navicular height decreases as the load increases, medial longitudinal arch angle increases as the load increases. ②During 100 ms before landing, there were differences between different loads in the joint angles of hip frontal plane, hip level plane and knee frontal plane(P<0.05). There were differences between different loads in the time of minimum navicular height in the joint angles of hip sagittal plane, hip frontal plane, knee sagittal plane, knee level plane and ankle level plane(P<0.05). During the landing, there were differences between different loads in the joint angles of hip frontal plane, hip frontal plane, hip level plane, knee frontal plane, knee sagittal plane and ankle level plane(P<0.05).③There were significant differences between different loads in PVGRF, PLGRF, VGRF-ROL, PGRF-ROL, LGRF-ROL and MGRF-ROL(P<0.01). ④ The positive correlation between navicular height and body weight, knee-width, ankle-width were significantly(P<0.01). The negative correlation between navicular height and Instep height was highly significant(P<0.01). ⑤ The positive correlation between navicular height with 0BW and joint angle in hip sagittal plane was highly significant(P<0.01), in 100 ms before landing. Under dynamic loading, the positive correlation between minimum navicular height and joint ankle in hip sagittal plane, knee sagittal plane were highly significant(P<0.01). The moment of minimum navicular height, under dynamic loading minimum navicular height and sagittal plane of the hip joint angle positive correlation is highly significant(P<0.01). During landing, maximum navicular drop height and frontal plane of the hip joint angle positive correlation is significant(P<0.05).⑥ There were no significant relationship between navicular height indexes and different directions of peak ground reaction force(P>0.05). Under dynamic loading, the negative correlation between minimum navicular height and PVGRF-ROL、PMGRF-ROL were significant(P<0.05), the positive correlation between navicular drop height and PMGRF-ROL was significant(P<0.05).Conclusions:①During buffer landing, the greater load people tended to be more through the coordination of the movement of each joint to buffer the impact of the bone is, reduce the single leg falling damage, to maintain the body balance.②During single landing, the touchdown lower limb are more inclined to extraversion, in order to balance the other side of body gravity and maintanining stability. However, this was the reason easy to ankle varus and other damage. Differ in only one time, there were significant differences in each direction ROL between two landing heights. Therefore, control of the load and buffer movement, was the key to the dynamic function activities to prevent injury. ④During buffer landing, nervous system pre-dominant lower limb hip, knee flexors active flexion, but the muscles of the lower limb joints pre-activated ability had no effect on navicular drop height. ⑤The subjects with lower navicular height and higher navicular drop height, when withstand the maximum impact force, the use of increased foot mobility, increasing the angle of rotation of the ankle joint approach to cushion the impact force. However navicular height higher and the navicular drop height smaller are use of the way with the hip flexor and lower the center of gravity, to absorb the impact force to maintain the stability of the human body.