The Effects Of The Ability Of Attentional Control On Lower Limb Biomechanical Characteristics During Walking

Purpose:As a function of the cognitive system,attentional control(AC)has been identified to have an important impact on performances of motor control.Thus,this study taked the walking as the object of the research,in order to explore the differences in lower limb biomechanical characteristics between people with diffenrent abilities of AC during different walking conditions and reaveal the intrinstic relationship between AC and motor control during walking as well as discuss the influences of walking condition on motor control.Moreover,this study aims to provide important theoretical guidance for the study of the effects of neurological function levels on motor control.Methods:Fifty volunteered undergraduate students who are complied with the requirements participated in the experiment.According to their reaction time of Stroop task,the top fifteen participants were assigned to High Attentional Control group(HAC)and the last fifteen participants were assigned to Low Attentional Control group(LAC).Then two groups randomly performed three conditions:(a)single 2-back task(ST 2-back),(b)single walking task(ST walking),(c)dual-task(DT).Cognitive outcomes and gait spatiotemporal parameters were measured.These cognitive outcomes,kinematics indexs and surface electromyograohy was measured by e-prime software,zebris,VICON with infrared motion capture system and Cometa wireless durface electromyography test system during different walking conditions.Continuous relative phase(CRP)was used to calculate inter-joint coordination.These differences in cognitive outcomes and lower limb biomechanical characteristics were analyzed using a 2(group:HAC,LAC)×2(ST,DT)repeated measures ANOVA with group as between-subject factor and task as within-subject factor.Results:The results of cognitive task:(1)The CR of HAC was significantly higher than that of LAC(P<0.05)and the differences in correct rate(CR)and RT between two walking conditions were statistically significant(P<0.01).Between-subject differences:(1)The differences in heel contact times,heel-forefoot times,average angle value of knee joint during swing phase between two groups as well as knee joint angular velocity at the start of swing phase and average knee joint angle values during stance phase and swing phase between two groups were statistically significant(P<0.05;P<0.05;P<0.05;P<0.05;P<0.05;P<0.01);(2)The differences in intergrated electromyography(iEMG)contribution rates of tibialis anterior(TA)during early and middle stance phases,lateral hamstring(LH)during the terminal of the stance phase,rectus femoris(RF)and LH during swing phase between two groups were statistically significant(P<0.05);(3)The differences in hip-knee mean absolute relative phase(MARP)and deviation phase(DP)during swing phase and knee-ankle MARP during stance phase between two groups were statistically significant(P<0.05).Within-subject differences:(1)The statistically significant kinematic indicators during walking included left foot progression angle,standardized step length and step width(P<0.05;P<0.05;P<0.01),the hip angles at the times of right foot landing and left foot off(P<0.05;P<0.01),the knee joint angle at the start of swing phase and average knee joint angle value during swing phase(P<0.05),average ankel joint angle value during stance phase and maximum ankle dorsiflexion angle(P<0.05;P<0.01),right step time,step frequency,heel-forefoot time(P<0.01;P<0.05;P<0.05),percentages of stance phase,the swing phase and double-support phase(P<0.05),the hip angular velocities at the time of right foot landing and the start of swing phase(P<0.01;P<0.05),the knee angular velocity at the time of right foot landing(P<0.05),the ankle angular velocity at the start of swing phase and average knee angular velocity value during swing phase(P<0.05;P<0.01);(2)The differences in iEMG contribution rates of RF,vastus medialis(VM),LH during the early stance phases and LH,MG during swing phase between two walking conditions were statistically significant(P<0.05);(3)The differences in the percentages of left and right forefoot contact times of LAC between two walking conditions were statistically significant(P<0.001),while there was only right forefoot contact times of HAC between two walking conditions were statistically significant(P<0.001).The difference in iEMG contribution rate of RF during middle stance phase in HAC between two walking conditions was statistically significant(P<0.05),while there was no same significant difference in LAC(P>0.05);(4)The differences in hip-knee MARP during swing phase and hip-knee DP during stance phase between two walking conditions were statistically significant(P<0.05).Conclusions:(1)The different ability of attentional control is an important indicator affecting individual cognitive function.Compared with LAC,HAC had higer CRs when completing different cognitive tasks.While,compared with ST,participants had higher CRs and shorter RTs in the DT;(2)Participants with different ability of attentional control presented different gait characteristics and lower inter-joint coordinations,which showed that compared with LAC,HAC presented more stable gait.While,the changes in the pattern of hip-knee inter-joint coordination during the swing phase and in the pattern of knee-ankle inter-joint coordination during the stance phase of LAC were greater than that of HAC.It was suggested that the ability of attentional control was related with the performances of motor control,which can be used as the theoretical support for the study of the effects of neurological function levels on motor control;(3)Not only the ability of AC would affect the performances of walking,but also different walking tasks would affect the performances of walking,which maily reflected in standardized step lengths,step width,foot progression angles,step time,step frequency,gait cycle,sagittal joint angles,sagittal joint angular velocities,muscle contribution rates,lower inter-joint coordinations and so on.