ABSTRACT
BACKGROUND: The coupling and coordination control of the multi-link rigid body of human body is the key to stable walking. It is reported that the use of cell phones greatly increases the chance of falling down stairs when walking; however, it lacks the analysis of the dynamic stability, motion coordination and joint mechanics of the lower limbs when walking down stairs with cell phone intervention. OBJECTIVE: To investigate the effects of cell phone on coupling control strategy of the multi-link rigid body in lower extremity during stair descent. METHODS: Twenty healthy university students were recruited and conducted the stair descent under no-interference (single task) and cell phone (phone task) randomly. Using the method of synchronous acquisition of 3D kinematics and dynamics, the kinetic and kinematic data were synchronously collected to acquire the parameters of stair descent under both conditions. RESULTS AND CONCLUSION: (1) The intervention of phone task significantly reduced the dynamic stability in anterior-posterior/media-lateral direction, the first knee extension moment peak, the first dorsiflexion moment peak, the second hip flexion moment peak in sagittal plane during stance phase, and significantly increased the mean and standard deviation of hip-knee/knee-ankle relative phase angles during swing phase. (2) It is concluded that when the gait of human body changes from time to time, the coupling control ability of multi-link rigid bodies decreased and the risk of falling increased. (3) The intervention of phone task reduces the supporting moment of lower limbs in the supporting phase, reduces the stability of adjacent joint coordination control in the swinging phase, reduces the dynamic stability in front, back and inside directions, and increases the risk of falling.
ABSTRACT
Objective To explore the plantar pressure and surface electromyography (sEMG) parameters during human stair walking, so as to provide theoretical support for foot structure design of dynamic walker, selection of power element and distribution of installation location. Methods Ten healthy young males were recruited to perform stair walking trials, respectively. The motion capture system, plantar pressure system and surface myoelectricity acquisition system were used to collect plantar peak pressure, trajectory of COP(center of pressure) and sEMG parameters of lower limb muscles at the same time. Results Compared with level walking, the percentage of stance time in the whole gait cycle increased during stair walking. The peak pressure of forefoot area increased during stair ascent, while the peak pressure of toe area decreased during stair descent. During stair walking, rectus femoris, biceps femoris, medialis and lateralis gastrocnemius played a main role in maintaining the stability of human body. Conclusions The plantar pressure distribution should be fully considered for foot structure design of dynamic walker and the function of main muscles should be considered for selection of power element and distribution of installation location.
ABSTRACT
@#Objective To evaluate the activities of vastus medialis, rectus femoris and vastus lateralis during stair descent in healthy youth. Methods Thirty healthy college students were recruited from the Capital Medical University 2015 admissions in 2016. The electrode was put on the dominant side of the quadriceps. Surface electromyography was used to record muscle activity during stair descent. Results During stair descent, the maximum amplitude and mean amplitude were significantly lower in rectus femoris than in vastus medialis and vas-tus lateralis (P<0.001). No significant difference was found between vastus medialis and vastus lateralis (P>0.05). Conclusion The activa-tion of both vastus medialis and vastus lateralis during stair descent is significantly higher than that of rectus femoris. The coactivation of vastus medialis and vastus lateralis is equal in healthy youth.
ABSTRACT
@#Objective To evaluate the activities of vastus medialis, rectus femoris and vastus lateralis during stair descent in healthy youth. Methods Thirty healthy college students were recruited from the Capital Medical University 2015 admissions in 2016. The electrode was put on the dominant side of the quadriceps. Surface electromyography was used to record muscle activity during stair descent. Results During stair descent, the maximum amplitude and mean amplitude were significantly lower in rectus femoris than in vastus medialis and vas-tus lateralis (P<0.001). No significant difference was found between vastus medialis and vastus lateralis (P>0.05). Conclusion The activa-tion of both vastus medialis and vastus lateralis during stair descent is significantly higher than that of rectus femoris. The coactivation of vastus medialis and vastus lateralis is equal in healthy youth.
ABSTRACT
Objective To collect the kinematics and kinetics functional parameters of healthy human lower limbs during stair ascent and descent, so as to provide data for designing the gait trajectory and selecting the driving components of the exoskeleton walker to achieve the motion of stair climbing. Methods Common staircase as an experimental setup was designed, and the three-dimensional (3D) motion capture system and 3D force plate were used to simultaneously measure the ankle, knee, hip motion information during stair ascent and descent. The movement characteristics of the lower limb during stair climbing was analyzed by SPSS statistical software and Origin graphics software, and the functional parameters during stair ascent and decent were also compared and analyzed. Results The joint angle at the sagittal plane, joint moment variation with gait and activity limits in lower limbs of healthy youth during stair ascent and descent were obtained by the experiment. The ranges of motion in ankle，knee and hip joints during stair ascent were -10.66°-13.26°, 6.85°-88.92°, 1.31°-50.18°,while those during stair descent were -37.42°-27.18°,9.83°-95.53°,8.01°-31.62°.The maximum ankle, knee and hip joint moment during stair ascent and descent were 1.788, 1.121, 0.946 N•m/kg, respectively. Conclusions The gait parameters variation with gait and the joint range of motion in human lower limb were significantly different during stair ascent and descent. Separate design targeting at stair ascent or stair descent is required for gait planning of walking aids, and the selection of driving element should consider the maximum moment in each joint during stair ascent and descent.
ABSTRACT
Objective To investigate the effects of heel heights on gait of young women when going downstairs, and analyze the injury risk of women wearing high-heeled shoes during stair descent. Methods The gait from 17 young women wearing shoes with 4 different heel heights during their stair descent was measured by infrared high-speed motion capture system. The subjects’temporal parameters of gait and 3D joint angles of lower extremity were calculated and analyzed. Results Compared with flat shoes, the gait cycle increased when wearing 3 cm, 5 cm, 7 cm high-heeled shoes during stair descent, and the stance phase proportion and double-support stance phase proportion decreased, while the step width also decreased evidently. For 5 cm, 7 cm high-heeled shoes, the ankle range of motion (ROM) in the sagittal plane would reduce significantly, and for all the 3 cm, 5 cm, 7 cm high-heeled shoes, the ankle ROM in transverse plane would increase during stair descent. Wearing 3 cm, 5 cm high-heeled shoes could make the knee ROM in the sagittal plane significantly reduce, while wearing 3 cm, 5 cm, 7 cm high-heeled shoes, the knee ROM in the transverse plane would increase evidently. Wearing 5 cm, 7 cm high-heeled shoes, the maximum hip flexion angle was greater than that of wearing flat shoes, and the minimum hip flexion angle would be also greater when wearing 3 cm, 5 cm, 7 cm high-heeled shoes. Conclusions During stair descent, with the increase of heel heights, the gait cycle and swing phase proportion increase, while the stance phase proportion, double-support stance phase proportion and step width decrease, which will raise the risk of falling. Meanwhile, the knee and ankle ROMs in sagittal plane decrease gradually, while those in transverse plane come to increase. The research findings can help to further understand the influence of heel heights on gait characteristics and patterns during stair descent and provide reference for possible injury risk analysis.