| Backgroud:Non-invasive brain stimulation(NIBS)has been widely used in neuroscience studies to induce changes in specific brain regions or network activities,and study their role in specific sports,cognitive or neurological function,which is most commonly used.One of the technologies is transcranial direct current stimulation(t DCS).In recent years,the research on t DCS on exercise capacity has become a hot spot,but combining continuous intervention t DCS and continuous longitudinal jumps,exploring the study of lower extremitic electromechanical characteristics is rare.This study will be based on the influence of the team’s early stage on the biomechanical mechanics of the incidental biological mechanics,and further explore the change in the activity of the intracranial and vertical venerability in the original place in continuous intervention.Exploring the influence of continuous intervention of t DCS on continuous longitudinal hopping capabilities of healthy people,providing a reference for the development and design of sports training aids.Methods:Subjects: 30 healthy male college students were randomly divided into two groups to receive a-t DCS and sham-t DCS(a-t DCS group:age:22.33±1.58 yr,height:173.53±7.39,weight:72.73±10.91kg;sham-t DCS:age: 22.87±1.96 yr,height: 175.40±5.22 cm,weight:72.00±10.86kg).study design: subjects were randomly divided into two groups and received t DCS stimulation twice a day for 5 days: anodal stimulation(anodal-t DCS,at DCS)and sham stimulation(sham-t DCS),with an interval of 20 minutes between two electrical stimuli per day(electrode position: anodal electrode: bilateral primary motor cortex(primary motor cortex,M1);cathode electrode: ipsilateral shoulder;current intensity: 2m A;stimulation time: 20 minutes).Infrared high-speed motion capture system(Vicon,UK)and wireless surface electromyography system(Noraxon,USA)are used to collect kinematics and lower limb EMG data during continuous longitudinal jump.The total height of continuous longitudinal jump,the stiffness of lower limbs and the time domain and frequency domain indexes of rectus femoris,lateral femoral muscle,tibialis anterior muscle,biceps femoris and gastrocnemius muscle were calculated.Statistical analysis: the total height of longitudinal jump,lower limb stiffness,time domain index and frequency domain index were analyzed by Two-way repeated-measures ANOVA(grouping * time).The inter-group factors were stimulation types(anode stimulation,sham stimulation).The intra-group factor was time(pre-test,post-test,follow-up).When the interaction between groups is significant,the simple effect analysis of each factor is carried out respectively.When the interaction effect is not significant,only the main effects of the two factors need to be analyzed separately.Pearson correlation analysis was used to explore the relationship between lower limb stiffness and EMG characteristics.The significant difference was set as p<0.05.Research Result:(1)The total height of longitudinal jump: under the condition of a-t DCS,the total height of continuous longitudinal jump in the post-test was significantly higher than that in the pre-test(16.25±2.33 m vs.17.25±2.2m,p=0.02).The total height of the follow-up test was significantly higher than that in the pre-test(16.25±2.33 m vs.17.00±2.34 m,p=0.026).There was no significant change in the total height of longitudinal jump after sham-t DCS intervention.(2)Lower extremity stiffness: under the condition of a-t DCS,the lower limb stiffness of post-test was significantly higher than that of pre-test(60.00±5.63 vs.65.14±7.34N/m/kg,p=0.03),but there was no significant difference after sham stimulation intervention(p> 0.05).(3)Muscle activation level: under the condition of a-t DCS,the activation level of J5 rectus was significantly higher than that of pre-test(9.10±3.79 vs.10.42±3.73,p= 0.016),the activation level of tibialis anterior muscle of J2 was significantly increased(0.35±0.22 vs.0.44 ±0.14,p=0.042),and under sham-t DCS condition,the activation level of J5 rectus was significantly higher than that of pre-test(7.97±2.76 vs.9.67±3.22,p=0.01).J2 tibialis anterior muscle activation level decreased significantly(0.59±0.20 vs.0.41±0.13,p=0.01).After a-t DCS intervention,there was a moderate positive correlation between rectus femoris activation level and lower limb stiffness(r=0.53,p=0.02),and a slight positive correlation between tibialis anterior muscle and tibialis anterior muscle(r = 0.27,p=0.01).(4)Muscle co-activation: under the condition of a-t DCS,the co-activation of J3 ankle antagonist muscle decreased significantly compared with that of the pretest(0.37±0.48 vs.0.23±0.20,p=0.01),and that of J4 ankle antagonist muscle decreased significantly(0.29±0.34 vs.0.24±0.24,p=0.021).Under the condition of sham-t DCS,the coactivation of J3 ankle antagonist muscle and J4 ankle antagonist muscle decreased significantly compared with the pretest(0.52±0.40 vs.0.26±0.17,p=0.001)and J4(0.47±0.41 vs.0.30±0.35,p=0.03).(5)mean power frequency: under the condition of a-t DCS,the mean power frequency of rectus femoris in post-test was significantly higher than that in pre-test(37.22±4.55 Hz vs.47.25±3.91 Hz,p=0.03).The mean power frequency of J2 lateral vastus muscle was significantly increased(45.31±7.32 Hz vs.57.11±5.38 Hz,p=0.013),the mean power frequency of J3 lateral vastus muscle was significantly increased(41.20±5.46 Hz vs.50.15±6.26 Hz,p=0.027),and the mean power frequency of J4 lateral vastus muscle was significantly increased(37.68±4.67 Hz vs.47.93±4.67 Hz,p=0.018).The mean power frequency of J5 lateral vastus muscle increased significantly(35.44±5.78 Hz vs.41.37±4.83 Hz,p=0.040).The mean power frequency of J3 biceps femoris and J5 biceps femoris increased significantly(35.15±3.73 Hz vs.42.33±4.28 Hz,p=0.03).The mean power frequency of J5 biceps femoris increased significantly(29.96±3.69 Hz vs.35.46±3.89 Hz,p=0.01).Under the condition of sham-t DCS,the average power frequency of each muscle did not change significantly.(6)Medium frequency: The median frequency of J2 vastus lateralis muscle increased significantly under a-t DCS condition(45.5±4.93 Hz vs.57.10±5.28 Hz,p=0.09);J3vastus lateralis muscle increased significantly under a-t DCS condition(46.36±4.79 Hz vs.51.34±5.89 Hz,p=0.01);J4 vastus lateralis muscle increased significantly under at DCS condition(41.02±7.47 Hz vs.47.13±6.38 Hz,p=0.005).The median frequencies of J1 biceps femoris were significantly increased(46.25±4.67 Hz vs.50.02±4.78 Hz,p=0.02);The median frequencies of J2 biceps femoris were significantly increased(43.16±6.78 Hz vs 47.01 ±4.79 Hz,p=0.026);The median frequencies of J3 biceps femoris were significantly increased(41.1±5.78 Hz vs.49.22±7.5 Hz,p=0.011)Under the condition of sham-t DCS,the median frequency of J2 lateral vastus muscle was significantly higher than that of pre-test(47.67±7.58 Hz vs.53.45±6.37 Hz,p=0.013),and the median frequency of J3 lateral vastus muscle was significantly higher than that of pretest(45.37±4.78 Hz vs.50.45±4.78 Hz,p=0.022).Conclusions:This study demonstrates that adopts the intervention for five days in a row,2 times a day the anode transcranial direct current stimulation can improve the longitudinal in the process of continuous vertical jump jump total height and vertical stiffness of lower limb,improve the rectus muscle and pretibial muscle activation level,improve the muscles around the ankle coordination,rectus,vastus lateralis muscle,shares biceps produce certain muscle fatigue resistance.Therefore,transcranial direct current stimulation can be used as a training aid technique to enhance lower limb strength and muscle control. |
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