ABSTRACT
Objective To analyze the impact of soldiers’ single-leg landing with load carriage on knee joint, and investigate its relationship with muscle strength, so as to provide references for daily load carriage training. Methods A total of 12 soldiers were required to perform single-leg landing from the 30 cm height without load carriage and with 15 kg load carriage,respectively.The kinematic and kinetic parameters were collected using Vicon motion capture system and AMTI force platform. The surface electromyography (sEMG) of anterior and posterior thigh muscles were also collected simultaneously, and the isokinetic strength during knee flexion and extension was tested. Results Compared with landing without load carriage, knee flexion angle and joint reaction force significantly increased during landing with 15 kg load carriage (P0.05). There was a significant negative correlation between peak moment of knee extension and vertical ground reaction force during single-leg landing without load carriage (P0.05). Conclusions Knee flexion angle and joint reaction force significantly increase during single-leg landing with 15 kg load carriage, the activation of anterior and posterior thigh muscles can relieved the ground reaction force during landing, and muscle strength plays some role in preventing landing injury.
ABSTRACT
Objective To determine the effect of trunk motion control on knee biomechanics during single-leg landing. Methods Twenty male healthy basketball players were recruited. The kinematics, kinetics parameters and surface electromyogram (EMG) of knee joints under trunk motion control during single-leg landing were studied by using Vicon motion Analysis system, Kistler force platform and Noraxon surface EMG system. Results Compared with natural landing, there were significant differences in flexion angle at initial contact moment, peak flexion angle and peak flexion moment during deeply inspiratory landing and landing with a stick, and a significantly larger flexion angle at initial contact moment, a larger peak flexion angle and smaller peak flexion moment were also found. Compared with natural landing, there was no statistical difference in peak valgus angle and peak valgus moment, as well as EMG activity of hamstrings, quadriceps muscles of the knee during deeply inspiratory landing and landing with a stick. Conclusions Deeply inspiratory landing or landing with a stick reduce the risk of anterior cruciate ligament (ACL) injury, and the results provide the theoretical basis for prevention of ACL injuries in basketball players during landing.
ABSTRACT
The higher anterior cruciate ligament (ACL) injury rate of females is one of the most sever athletic-related problems today. The purpose of this study is to compare the lower extremity kinematics between male and female during single leg landing.Six male and four female healthy subjects participated in this study. They jumped from a 32 cm high box and landed with the dominant leg. The landing action was filmed with three video cameras. The knee flexion, knee valgus/varus, and hip adduction/abduction angle and angle velocity were calculated.In female subjects, the knee flexion angle and hip adduction angle were greater compared to males. Also, the knee valgus velocity and hip adduction velocity were higher in females.Our results suggest that knee valgus kinematics may be related to hip adduction. It is important to evaluate hip kinematics when considering knee kinematics to prevent knee ligament injuries.