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BACKGROUND:Transcranial direct current stimulation(tDCS),as a non-invasive brain stimulation technique,can enhance human muscle strength or improve single-leg landing stability instantly,but no relevant research has demonstrated this yet. OBJECTIVE:To investigate the effect of tDCS on the stability of single-leg landings in human subjects. METHODS:Male undergraduate students from Wuhan Sports University were recruited as study participants.They were divided into two groups,A(n=6)and B(n=5),using a random number table.Group A underwent a sham stimulation session followed by a 3-day washout period,after which they received tDCS.Conversely,Group B received tDCS initially,followed by a 3-day washout period,and subsequently underwent the sham stimulation session.Following the respective stimulation sessions,an immediate single-leg landing test was administered to assess and collect biomechanical parameters.Data resulting from the tDCS intervention were aggregated and analyzed as the experimental group dataset,whereas data stemming from the sham stimulation were consolidated as the control group dataset. RESULTS AND CONCLUSION:Regarding core stability,the tDCS intervention showed a significant interaction with landing height on the maximal trunk flexion angle(P＜0.05).A paired comparison of the data showed a significant decrease in the maximum trunk flexion angle following true stimulation compared to sham stimulation at a 30-cm landing height.Additionally,the tDCS intervention had a significant main effect on the maximum trunk lateral bending angle and the mean trunk lateral bending angular velocity(P＜0.05).Following true stimulation,there was a significant decrease in the maximum trunk lateral bending angle and the mean trunk lateral bending angular velocity compared to sham stimulation.In terms of lower limb joint stability,the tDCS intervention had a significant main effect on the maximum dynamic ankle valgus angle(P＜0.05).This resulted in a significant decrease in the angle following true stimulation compared to sham stimulation.In addition,the tDCS intervention had a significant main effect on the peak muscle activation of the lateral head of the gastrocnemius lateralis(P＜0.05).This showed a significant increase after true stimulation compared to sham stimulation.An interaction between the tDCS intervention and landing height was observed for the peak muscle activation of the tibialis anterior(P＜0.05).Paired comparison analyses revealed a significant increase in muscle activation after true stimulation specifically at a 60-cm landing height.Regarding center of pressure stability,there were no significant interactions or main effects of the tDCS intervention on the mean lateral displacement,mean lateral displacement velocity,mean anterior-posterior displacement,or mean anterior-posterior displacement velocity at the center of pressure(P＞0.05).Furthermore,the tDCS intervention had no significant main effects on any of the center of pressure indicators(P＞0.05).In conclusion,tDCS can immediately improve core stability and lower limb joint stability during single-leg landing,making it an effective warm-up technique for improving single-leg landing stability and reducing the risk of lower limb injuries.
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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.
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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.
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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.