| Objective:Studies have shown that balance control(BC),especially the BC during simultaneous cognitive tasks,is an important training goal for young basketball players,which can both improve their sports performance and prevent the occurrence of sports injuries.Studies have confirmed that dual-task postural control should not reach the adult level until at least 15 or 16,and 13～15 are in the special training stage of youth basketball players,which is a key period for athletes to conduct special training.Previous studies have confirmed that motor-cognitive dual-task training(DTT)is an effective method that can produce the combined effect of motor training and cognitive training,and can improve postural control and gait performance more effectively than single training.However,there are few studies investigating the effects of motor-cognitive dual-task training on balance control,especially under cognitive interference,in basketball players.Based on this,the purpose of this study is(1)to verify the test-retest reliability of BC index,cognitive performance index and cerebral blood oxygen data index under dual task conditions.(2)to explore the characteristics of BC under different cognitive load conditions,as well as the cognitive performance and brain function characteristics during BC in young basketball players aged 13 to 15.(3)To construct a DTT program suitable for improving BC of student basketball players aged 13～15,and to demonstrate the scientific and feasibility of the training program.(4)To explore the effects of DTT on BC under different cognitive load conditions of student basketball players aged 13～15.Methods:Study 1:Adopted the within-subjects design,20 students were selected to complete the balance control task under three cognitive load conditions.Application group correlation coefficient(intraclass correlation coefficient,ICC)and correlation coefficient(r)to evaluate the retest reliability of balance control index(COP whole path length,COP circumference area,COP unit area path length,COP swing velocity),cognitive performance index(N-back task accuracy and response time)and cerebral oxygen data index(HbO).Study 2:Adopted the experimental design of 2(group:college student group,middle school student group)×3(load intensity:zero-load,low-load,high-load),through the sample size calculation,18 college basketball players and 20 middle school students basketball players were included.Used repeate measures analysis of variance to compare the differences of balance control,cognitive performance and HbO in prefrontal cortex and motor cortex,and to analyze the correlation between HbO concentration and balance control index.Study 3:The motor-cognitive dual-task training program for student basketball players aged 13～15 was preliminarily constructed by expert interview method.The Delphi method was used for two rounds of expert consultation to finally determine the intervention program.Fifteen student-basketball players were included in the 2-week pre-experiment to verify the feasibility of the program.Study 4:Used the three-factor mixed experimental group 2(experimental group,control group)2(test order:pre-test,post-test)3:load strength:zero-load,low-load,high-load).After the sample size calculation,25 subjects were included in the experimental group and the control group.Used repeate measures analysis of variance to compare the differences in balance control,cognitive performance and prefrontal cortex and motor cortex,and used Pearson’s correlation to analyze the correlation between HbO concentration and balance control indicators.The experimental group used the motor-cognitive task training program constructed by Study 3(3 times a week for 8 weeks),and the control group conducted 8 weeks of corresponding general basketball training.Results:In Study 1,The ICC value of the balance control index(COP whole path length,COP circumference area,COP unit area path length,COP swing velocity)of the two tests was 0.609～0.919,For the medium and above consistency range,The r value was 0.580～0.816,For the significant moderate and highly positive correlation.The ICC values for the cognitive performance measures(ACC and RT for the N-back task)were 0.852～0.975,For a good consistent range,The r values of 0.896～0.978,Is a significant and high positive correlation.The ICC value of the fNIRS data index(HbO signal intensity in the left and right prefrontal lobe,motor cortex)was 0.818～0.984,For a good consistent range,the r values of 0.739～0.984,For a significant and highly positive correlation,and the total mean brain function activation maps of the two tests were similar in the three cognitive load conditions.In Study 2,in no and low cognitive load,there were no significant difference in COP whole path length,COP circumference area and COP swing velocity(p>0.05)between college students and middle school students.In high cognitive load,there wa significant difference in COP whole path length(p>0.001)between two groups.In no and high cognitive load,there were significant difference in COP unit area path length(p<0.05)two groups.In low cognitive load,there was significant difference in COP unit area path length(p>0.05)two groups.In high cognitive load,there were significant difference in COP swing velocity(p<0.05)two groups.The intensity and range of brain activation in the three cognitive load conditions were greater than those in the university group,while the mean HbO oxygen signal concentration in all channels of the two groups was not significantly different(p>0.05).in no cognitive load,there was a significant positive correlation between HbO oxygen signal concentration of CH3 and COP unit area path length(r=0.488,p=0.029),there was a significant negative correlation between HbO oxygen signal concentration of CH6 and COP circumference area(r=-0.684,p=0.013),there was a significant positive correlation between HbO oxygen signal concentration of CH6 and COP unit area path length(r=0.730,p=0.001),there was a significant positive correlation between HbO oxygen signal concentration of CH39 and COP unit area path length(r=0.659,p=0.002).In low load,there was a significant positive correlation between HbO oxygen signal concentration of CH37 and COP circumference area(r=0.472,p=0.035),there was a significant positive correlation between HbO oxygen signal concentration of CH39 and COP circumference area(r=0.452,p=0.045),there was a significant negative correlation between HbO oxygen signal concentration of CH39 and COP unit area path length(r=-0.478,p=0.033).In high load,there was no correlation between Hb0 blood oxygen signal concentration and balance control index in all activation channels.Study 3:The main content of the primary construction of motor-cognitive program involves four aspects:dribbling,passing and catching,shooting and footwork.In the first round,18 expert consultation questionnaires were sent,and 16 valid questionnaires were collected,with an effective recovery rate of 88.89%.In the second round,16 questionnaires were sent and 16 valid questionnaires were collected,with an effective recovery rate of 100%.Cv of all indexes in the first round of expert correspondence was less than 20%,and the average coefficient of variation was 14.042%.The Cv of all indexes in the second round of expert correspondence was less than 15%,and the average coefficient of variation was 10.426%.Kendall’W is 0.287 in the first round and 0.437 in the second round(p<0.001).The training scheme adjusted by 2 weeks pre-experiment is more feasible.Study 4:In pre-test,there was no significant difference in COP whole path length between the two groups(p>0.05),while in post-test,the experimental group was significantly lower than the control group(p<0.05).For the experimental group,COP whole path length of post-test was significantly lower than pre-test,while there was no significant difference in the control group between pre-and post-test.No matter pre-or post-test,there were significant differences between the three different cognitive loads between the two groups(p<0.05).In low cognitive load and high cognitive load,there were significant differences in COP circumference area between pre-and post-the condition(p<0.05),but no significant differences in the no cognitive load condition(p>0.05).There was no significant difference in COP unit area path length between preand post-test of the two groups(p>0.05).For the experimental group,in zero-and low-load condition,there was no significant difference in COP unit area path length between preand post-test(p>0.05),while in high-load condition,there was no significant difference between pre-and post-test(p<0.05).For the control group,in all three condition,there was no significant difference in COP unit area path length between pre-and post-test(p>0.05).There were significant differences in average COP swing velocity between pre-and post-test in the two groups(p<0.001),and no significant differences in COP swing velocity between the two groups in the pre-test(p>0.05),while in post-test,the COP swing velocity of the experimental group was significantly lower than that of the control group(p<0.001).In zero-and low-load condition,there was no significant difference in COP swing velocity between pre-and post-test(p>0.05),while there was significant difference in COP swing velocity between pre-and post-test(p<0.001).The ACC in post-test was significantly higher than pre-test(p<0.05).The ACC in post-test was significantly higher than pre-test(p<0.05),and the RT in post-test significantly lower than pre-test(p<0.001),in the control group,RT in post-test was also lower than pre-test(p<0.08).In the experimental group,the activation channels decreased after the experiment.For the activation range,the activation range decreased in zero-and low-load condition.In the experimental group,there were significant differences in the mean HbO oxygen signal concentration between pre-and post-test in all three conditions(p<0.05).In the control group,there was significant difference between pre-and post-test in zero-load condition(p<0.05),while there were no significant difference between pre-and post-test in low-and high-load conditions(p>0.05).In the experimental group,in the zero-load condition,there was a significant positive correlation between the change of HbO oxygen signal concentration of CH9 and the changes of COP whole path length(r=0.422,p=0.0358)and COP whole path length(r=0.421,p=0.0358),there was a significant positive correlation between the change of HbO oxygen signal concentration of CH16 and the change of COP circumference area(r=0.473,p=0,0170).In the low-load condition,there was a significant negative correlation between the change in HbO oxygen signal concentration of CH1 and the changes of COP whole path length(r=-0.663,p<0.01),COP circumference area(r=-0.449,p=0.0242),COP swing velocity(r=-0.663,p<0.01).In high-load condition,there is no significant correlation between the changes of blood oxygen concentration and the changes of balance control index(p>0.05).Conclusions:(1)In zero-,low-and high-load,student basketball players aged 13～15 in no cognitive load,low cognitive load and high cognitive load three conditions of balance control indicators(COP whole path length,COP circumference area,COP unit area path length,COP swing velocity),N-back task indicators(ACC,RT)and fNIRS data(HbO)test-retest reliability is higher,can be used as an indicator to assess the ability of balance control.(2)Dual-task balance control is weaker in student basketball players aged 13～15 than in college basketball players.Therefore,the automatic control ability of middle school basketball players also has room for improvement.For basketball,appropriate multitask interventions should facilitate brain attentional resource recruitment and balance control.(3)After two rounds of Delphi expert consultation,the motor-cognitive dual-task training program for student basketball players aged 13～15,mainly composed of dribbling,passing and catching,shooting and footwork practic,and proved to be feasible,safe and scientific,and provides the action guide and experience framework for the design and implementation of frontline coaches and researchers to DTT.(4)DTT improved the balance control under different cognitive loads of student basketball players aged 13～15,and also improved the cognitive performance under dual-task conditions,and affected the cerebral blood oxygen signal concentration changes in the prefrontal cortex and motor cortex,which made the brain activation range more concentrated,the overall activation intensity weakened in the prefrontal cortex and motor cortex.Therefore,exercise-cognitive dual task training can be used as an effective strategy to improve balance control under different cognitive loads. |
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