BACKGROUND:Early postural adjustments serve as preparatory measures for forthcoming actions or potential disruptions in posture,thereby facilitating improved movement execution and mitigating destabilizing effects caused by posture interference. OBJECTIVE:To investigate the characteristics of temporal and intensity parameters of key lower limb muscles during early postural adjustment phase when stroke patients with varying levels of balance initiate walking at a self-selected comfortable pace. METHODS:The characteristics of early postural adjustments in 16 stroke patients were observed.Sixteen patients were divided into a non-fall group(n=8)and a fall group(n=8)based on the history of falls and Berg Balance Scale scores.Noraxon inertial sensors and Noraxon Ultium EMG wireless surface electromyography were utilized to collect body kinematic data and surface electromyography data during gait initiation.Muscle activation time and activation sequence of six key muscles in the lower limbs(tibialis anterior,medial and lateral gastrocnemius,rectus femoris,lateral femoris and biceps femoris muscles)during the early postural adjustment phase,as well as normalized electromyography integral values for the four time windows(each 150 ms)before gait initiation,were analyzed. RESULTS AND CONCLUSION:Stroke patients with a history of falls exhibited earlier activation times for the six key muscles in the lower limbs during gait initiation compared with those in the non-fall group.The fall group demonstrated significantly earlier activation times for tibialis anterior,lateral head of gastrocnemius,and vastus lateralis(P<0.01,P<0.05).In contrast,the non-fall group displayed a consistent pattern of activating extensor muscles before flexor muscles,with thigh muscle activation preceding calf muscle activation.However,in the fall group,calf extensor muscle activation occurred prior to thigh extensor muscle activation,and the vastus lateralis was activated even earlier.The tibialis anterior was the last activated muscle in both groups.Specifically during T3(>-300 to-150 ms),the tibialis anterior exhibited significantly higher activity in the fall group compared with the non-fall group(P<0.05),while the lateral head of gastrocnemius demonstrated significant inhibition during T3(P<0.05)and the medial head of gastrocnemius showed significant inhibition during both T3 and T4(>-150 to 0 ms)stages compared with the non-fall group(P<0.01,P<0.05).To conclude,stroke patients with varying balance abilities employ distinct early postural adjustment strategies prior to stepping,as evidenced by differences in muscle activation timing,recruitment order,and muscle activity amplitude.Patients at a high risk of falling exhibit prolonged duration of early postural adjustment and delayed initiation of gait,indicating earlier activation of the tibialis anterior muscle and inhibition of gastrocnemius muscle activity.These delays in gait initiation and variations in muscle recruitment strategies may contribute to unstable posture and an increased susceptibility to falls.

Objective To observe the effects of Ditan Yizhi Decoction on learning and memory ability,structure of hippocampal tissue,neuronal morphology of hippocampus,and the expression of endoplasmic reticulum autophagy-related protein FAM134B in hippocampal tissue;To explore the mechanism of its therapeutic effect on vascular dementia.Methods Totally 32 SD rats were randomly divided into sham-operation group,model group,donepezil group and Ditan Yizhi Decoction group,with 8 rats in each group.The model group,donepezil group and Ditan Yizhi Decoction group were prepared with a modified permanent ligation method of bilateral common carotid arteries to create a rat model of vascular dementia,the common carotid artery was separated in the sham-operation group,but not ligated.After modeling,the donepezil group was given donepezil hydrochloride,Ditan Yizhi Decoction group was given Ditan Yizhi Decoction,and the sham-operation group and model group were given equal volume of distilled water for gavage for 4 consecutive weeks.Morris water maze experiment was used to evaluate the learning and memory ability,HE staining and Nissl staining were used to observe the morphological changes of hippocampus,ultrastructure of hippocampal neurons was observed using transmission electron microscopy,Western blot was used to detect the protein expression of FAM134B and p-FAM134B in hippocampal tissue.Results Compared with the sham-operation group,the escape latency period was prolonged of the rats in model group,and the number of crossing the original platform and the duration of stay in the target quadrant was reduced(P<0.01),the gap between neurons in CA1 region of the hippocampus increased,the cell morphology was irregular,the boundaries were blurred,the neurons shrinked,the Nissl bodies dissolved and broke,the number decreased,the endoplasmic reticulum arrangement was scattered,mitochondria swelled and deformed,and the expressions of FAM134B and p-FAM134B protein in hippocampal tissue increased(P<0.01).Compared with the model group,the escape latency period of rats in donepezil group and Ditan Yizhi Decoction group were significantly shortened,and the number of crossing the original platform and the duration of stay in the target quadrant were increased(P<0.01),the morphology and quantity of neurons in CA1 region of the hippocampus were more regular,with a decrease in neuronal pyknosis,an increase in the number of Nissl bodies,and a reduction in dissolution and fragmentation,the swelling and deformation of the endoplasmic reticulum were restored,and the expression of FAM134B and p-FAM134B protein in hippocampal tissue increased(P<0.01).Moreover,the effects of Ditan Yizhi Decoction group were better than those of the donepezil group(P<0.01).Conclusion Ditan Yizhi Decoction can improve the learning and memory ability and the morphology of neurons in vascular dementia rats.The mechanism may related to increasing the expression and phosphorylation of FAM134B protein,thereby promoting endoplasmic reticulum autophagy.