Objective To explore the correlation between single-leg standing posture control and ankle plantar flexor muscle stability,so as to provide a new theoretical basis for improving the ability of human posture control.Methods A total of 20 healthy male college students were randomly selected as the experimental subjects.The iBalance tester and training system was used to test the trajectory data of the center of pressure(COP)of the foot standing on one leg.The CON-TREX MJ multi-joint isokinetic test and training system was used to test the moment amplitude data during the contraction of ankle plantar flexor muscles.Univariate repeated measures variance analysis was used to analyze the standard deviation data of ankle plantar flexor moment amplitude between groups.The Pearson correlation coefficient was used to study the correlation.Results The greater the intensity of the muscle stabilization task performed by the ankle plantar flexor muscle,the greater the standard deviation of the moment amplitude.The C90 area was positively correlated with the coefficient of variation(CV)of the 10％maximum voluntary contraction(MVC)moment of ankleplantar flexor muscle(r=0.761,P＜0.05)during single-leg standing without interference.The C90 area was positively correlated with the CV(r=0.632,P＜0.05)of the 30％MVC moment of ankle plantar flexor muscle during single-leg standing.When the proprioception was interfered during single-leg standing,the C90 area was positively correlated with the CV(r=0.583,P＜0.05)of the 20％MVC moment amplitude of ankleplantar flexor muscle.Conclusions With the increasing difficulty of muscle strength stabilization performed by the ankle plantar flexor muscles,muscle stability decreases.There is a positive correlation between ankle plantar flexor strength stability and single-leg standing posture control.Compared with the case without interference,under visual and proprioceptive interference,an additional information input is reduced or disturbed,and it is more difficult to maintain body balance,and the ankle plantar flexor muscle needs a higher muscle stability in the force mode to participate in the posture control of the human body during single-leg standing.

Objective To explore the effect of cognitive-motor dual tasks with different cognitive loads(none,simple and difficult)on activation of prefrontal cortex and static posture control in young man.Methods From June to July,2024,27 healthy male college students were recruited in Hebei Normal University.Static postural control parameters(C90 area),lower limb electromyography data(muscle energy proportion)and pre-frontal cortex hemodynamic signals of subjects under single task without cognitive load,dual-task with simple cognitive load,and dual-task with difficult cognitive load were collected using a balanced testing and training system,a wireless surface electromyography device,and functional near-infrared spectroscopy technology.Results The C90 areas of dual-tasks with simple and difficult cognitive load were smaller than that of the single task without cognitive load(P<0.05).The proportion of β band energy in the medial and lateral gastrocnemius mus-cles in the dual-task with simple cognitive load was greater than that in the single task without cognitive load(P<0.05),while the proportion of piper band energy in the lateral gastrocnemius muscle and tibialis anterior muscle was less(P<0.05).During dual-task with difficult cognitive load,the activation levels of bilateral ventro-lateral prefrontal cortex and right dorsolateral prefrontal cortex were higher than those in the single task without cognitive load(P<0.05).Conclusion Dual tasks with appopriate cognitive loads are effective on postural stability in young man.Simple cognitive load promote posture maintenance through optimizing the neuromuscular control of the lower limb muscle groups,while difficult cognitive load through activating the right prefrontal cortex involved in working memory and executive control,involving the neurocognitive compensatory.

Objective To explore the correlation between single-leg standing posture control and ankle plantar flexor muscle stability,so as to provide a new theoretical basis for improving the ability of human posture control.Methods A total of 20 healthy male college students were randomly selected as the experimental subjects.The iBalance tester and training system was used to test the trajectory data of the center of pressure(COP)of the foot standing on one leg.The CON-TREX MJ multi-joint isokinetic test and training system was used to test the moment amplitude data during the contraction of ankle plantar flexor muscles.Univariate repeated measures variance analysis was used to analyze the standard deviation data of ankle plantar flexor moment amplitude between groups.The Pearson correlation coefficient was used to study the correlation.Results The greater the intensity of the muscle stabilization task performed by the ankle plantar flexor muscle,the greater the standard deviation of the moment amplitude.The C90 area was positively correlated with the coefficient of variation(CV)of the 10％maximum voluntary contraction(MVC)moment of ankleplantar flexor muscle(r=0.761,P＜0.05)during single-leg standing without interference.The C90 area was positively correlated with the CV(r=0.632,P＜0.05)of the 30％MVC moment of ankle plantar flexor muscle during single-leg standing.When the proprioception was interfered during single-leg standing,the C90 area was positively correlated with the CV(r=0.583,P＜0.05)of the 20％MVC moment amplitude of ankleplantar flexor muscle.Conclusions With the increasing difficulty of muscle strength stabilization performed by the ankle plantar flexor muscles,muscle stability decreases.There is a positive correlation between ankle plantar flexor strength stability and single-leg standing posture control.Compared with the case without interference,under visual and proprioceptive interference,an additional information input is reduced or disturbed,and it is more difficult to maintain body balance,and the ankle plantar flexor muscle needs a higher muscle stability in the force mode to participate in the posture control of the human body during single-leg standing.

Objective To explore the effect of cognitive-motor dual tasks with different cognitive loads(none,simple and difficult)on activation of prefrontal cortex and static posture control in young man.Methods From June to July,2024,27 healthy male college students were recruited in Hebei Normal University.Static postural control parameters(C90 area),lower limb electromyography data(muscle energy proportion)and pre-frontal cortex hemodynamic signals of subjects under single task without cognitive load,dual-task with simple cognitive load,and dual-task with difficult cognitive load were collected using a balanced testing and training system,a wireless surface electromyography device,and functional near-infrared spectroscopy technology.Results The C90 areas of dual-tasks with simple and difficult cognitive load were smaller than that of the single task without cognitive load(P<0.05).The proportion of β band energy in the medial and lateral gastrocnemius mus-cles in the dual-task with simple cognitive load was greater than that in the single task without cognitive load(P<0.05),while the proportion of piper band energy in the lateral gastrocnemius muscle and tibialis anterior muscle was less(P<0.05).During dual-task with difficult cognitive load,the activation levels of bilateral ventro-lateral prefrontal cortex and right dorsolateral prefrontal cortex were higher than those in the single task without cognitive load(P<0.05).Conclusion Dual tasks with appopriate cognitive loads are effective on postural stability in young man.Simple cognitive load promote posture maintenance through optimizing the neuromuscular control of the lower limb muscle groups,while difficult cognitive load through activating the right prefrontal cortex involved in working memory and executive control,involving the neurocognitive compensatory.

Objective To classify the foot types of young Chinese males,extract characteristic indicators of foot types,and construct a standard foot type database.Methods Foot type data from 1 483 healthy young male individuals were collected.Spectral clustering algorithm was utilized to categorize foot types,and a deep neural network(DNN)was employed for training the classification model.Layer-wise relevance propagation(LRP)and the correlation coefficient method were combined to extract foot type features,and the differences in various foot type characteristics were compared.Results Spectral clustering yielded 4 distinct foot type categories.Foot type 1 was characterized by a high-arched foot with a prominent big toe,inwardly rotated 5th toe,and a high heel with a wide foot;foot type 2 was characterized by a narrow foot with hallux valgus;foot type 3 was characterized by a low-arched foot with hallux valgus;foot type 4 was characterized by a high-arched foot with a prominent big toe.By integrating interpretable neural networks and the correlation coefficient method,nine indicators were extracted from 27 foot type indicators,including the heel to the sole length,hallux height,navicular bone height,lateral malleolus height,hallux valgus angle,5th toe angle,dorsal foot circumference,heel angle,and longitudinal arch angle.The classification model constructed with these extracted indicators achieved an overall discrimination accuracy rate of 93.67％.Conclusions Chinese young males can be classified into four typical foot types.By examining the rearfoot,midfoot,and forefoot regions,nine key foot morphology parameters,including length,height,circumference,and angle,can be extracted.These parameters provide both theoretical and empirical support for establishing normative data on foot morphology for Chinese young males and for advancing biomechanical researches on the foot and ankle.

Objective To classify the foot types of young Chinese males,extract characteristic indicators of foot types,and construct a standard foot type database.Methods Foot type data from 1 483 healthy young male individuals were collected.Spectral clustering algorithm was utilized to categorize foot types,and a deep neural network(DNN)was employed for training the classification model.Layer-wise relevance propagation(LRP)and the correlation coefficient method were combined to extract foot type features,and the differences in various foot type characteristics were compared.Results Spectral clustering yielded 4 distinct foot type categories.Foot type 1 was characterized by a high-arched foot with a prominent big toe,inwardly rotated 5th toe,and a high heel with a wide foot;foot type 2 was characterized by a narrow foot with hallux valgus;foot type 3 was characterized by a low-arched foot with hallux valgus;foot type 4 was characterized by a high-arched foot with a prominent big toe.By integrating interpretable neural networks and the correlation coefficient method,nine indicators were extracted from 27 foot type indicators,including the heel to the sole length,hallux height,navicular bone height,lateral malleolus height,hallux valgus angle,5th toe angle,dorsal foot circumference,heel angle,and longitudinal arch angle.The classification model constructed with these extracted indicators achieved an overall discrimination accuracy rate of 93.67％.Conclusions Chinese young males can be classified into four typical foot types.By examining the rearfoot,midfoot,and forefoot regions,nine key foot morphology parameters,including length,height,circumference,and angle,can be extracted.These parameters provide both theoretical and empirical support for establishing normative data on foot morphology for Chinese young males and for advancing biomechanical researches on the foot and ankle.

BACKGROUND:Research on foot and ankle proprioception is crucial for the rehabilitation of chronic ankle instability and geriatric diseases as well as for the improvement of body posture control and motor performance.Previous studies have often studied the sensory evaluation of the foot and ankle joints separately,which has limitations for a comprehensive understanding of their sensory function. OBJECTIVE:The foot and ankle complex is the only part in direct contact with the support surface,and plays an important role in the collective sensory feedback and regulation and balance control.By combing the existing investigation and research of foot and ankle ontology,the measurement and evaluation methods of the sensation of the foot and ankle complex are combed,in order to pave the way and provide the theoretical basis for future related studies. METHODS:Chinese terms"(foot OR foot ankle OR ankle)AND(sensation OR proprioception)"and English terms"(foot OR ankle)AND(feel OR proprioception)"were used as the keywords for retrieving relevant literature in the Web of Science,PubMed,and CNKI.We understood the basic concepts,current status and scope of research on the foot and ankle,summarized and evaluated the proprioceptive evaluation methods of the foot and ankle,and finally included 57 papers for further review. RESULTS AND CONCLUSION:The evaluation of foot and ankle complex sensation was mainly divided into sensory evaluation of the foot and proprioceptive evaluation of the ankle joint.The sensory evaluation of the foot mainly describes the sensation of the skin and the sensory feedback under the intervention conditions.The methods mainly include the pressure sensory threshold test,the two-point discrimination test of the foot(planar and plantar),and the duration test of skin vibration sensation.Ankle joint proprioception evaluation focuses on the description of joint position,motion range,force value and functional performance.The methods are mainly divided into static joint angle reset test,motion minimum threshold test,force perception reproduction test and dynamic balance,speed and walking ability tests.The report of quantitative results is generally expressed by"an error,"which is generally divided into absolute error,relative error,constant error,etc.To conclude,the foot and ankle complex has specific sensory capabilities,including foot sensation and ankle proprioception,which affect the quality of life and athletic performance of humans.Weakness of both foot sensation and ankle proprioception is associated with reduced human balance,and the combined measurements of the two can comprehensively and effectively evaluate foot and ankle function.The combination of foot and ankle sensory measures is selected according to different research needs and various influencing factors such as environment,emotion and reporting style are fully considered,to improve the validity of measurement and evaluation.

Objective:To explore the characteristics of arch function in patients with flexible flat foot by comparing the differences of static and dynamic arch function between normal and flexible flat foot patients,provide theoreti-cal reference for the functional distinction of different types of foot arch. Method:Thirty adult male subjects were recruited.Normal and flat feet were distinguished by foot printing method,and flexible flat feet were screened by heel raising test and passive toe raising test.Sixteen normal feet and fourteen patients with flexible flat feet were screened.Static arch stiffness was calculated by the differ-ence of arch height between natural standing and sitting at different loading positions,and the relative arch height at the beginning of the middle support period,change value of relative arch height,change rate of rela-tive arch height and proportion of middle foot impulse during walking were evaluated by 3D motion capture and plantar pressure.The correlation between static arch stiffness and dynamic arch function was analyzed by partial correlation(controlling step speed). Result:The static arch stiffness of flexible flat feet was lower than that of normal feet(P＜0.05).The results of dynamic arch function test showed that the relative height and change rate of arch height in the middle of walking support decreased gradually in both normal and flexible flat feet,the change value and change rate of arch height in flexible flat feet at the beginning of the middle of walking support period were lower than those in normal feet(P＜0.05).The proportion of impulse of flexible flat feet in walking support was higher than that of normal feet(P＜0.05).Partial correlation analysis showed that the relative height,relative height change value and relative height change rate at the beginning of middle support were positively correlated with static arch stiffness(r=0.580-0.679,P＜0.05),the proportion of middle foot impulse was negatively correlat-ed with static arch stiffness(r=-0.478,P＜0.05). Conclusion:During walking,the arch of the foot continued to decline in the middle of support,and the rate of decline gradually decreased.The adaptability of static and dynamic arches to loading in patients with flexi-ble flat feet was lower than that of normal feet.It is the key of ankle rehabilitation to improve the weight bearing adaptability of arch in patients with flexible flat foot.Arch stiffness is correlated with dynamic arch function,which is an important reference value for the functional division of different types of foot arch.

Objective To explore the patterns of functional gait asymmetry during the support phase and the differentiation of bilateral foot functions,to gain insights into the human movement compensa-tion mechanisms and stability control characteristics,so as to provide theoretical references for the pre-vention and rehabilitation treatment of unilateral foot and ankle injuries.Methods Twelve young females with normal feet were recruited,and the time percentage of each phase of the support period,the change of longitudinal arch angle,the vertical ground reaction force and the center of plantar pressure trajectory of the dominant and non-dominant feet were collected by using a three-dimensional motion capture and a high-frequency plantar pressure testing system when the subjects walked at the optimum speed with the incremental loading of weights[0%body weight(BW),10%BW and 20%BW].The ef-fects of laterality(dominant foot,non-dominant foot)and load(0%BW,10%BW,20%BW)on arch changes and gait parameters,and the interactions between them,were analyzed using a two-way re-peated-measures ANOVA.Results The factors of laterality and load interacted significantly on arch changes,but not on gait parameters.(2)Compared with 0%BW,the time percentage of the buffering phase of the nondominant feet with the load of 20%BW increased(P<0.05),while that of the domi-nant ones decreased(P<0.05),with an increase in the buffering load of both feet with the load of 20%BW(P<0.05)and the buffering force excursion of both feet with the load of 10%BW(P<0.05).More-over,changes in longitudinal arch angle increased(P<0.05)with the load of 10%and 20%BW,the pedal extension load rate increased(P<0.05)with the above BW load in the non-dominant feet,and the horizontal slope of pedal extension decreased(P<0.05)with 20%BW load in the dominant feet.Compared with 10%BW,when the feed was loaded 20%BW,the time percentage in the buffering phase and the buffering force offset of the dominant feet decreased(P<0.05),while the buffering load of both feet increased(P<0.05).(3)Compared with the non-dominant feet,for the dominant feet,the buffering load rate at the load of 10%and 20%BW and changes in the longitudinal arch angle at the load of 20%BW decreased(P<0.05),while the horizontal slope of the pedal extension without load in-creased(P<0.05).Conclusion Walking with load induces function differentiation in bilateral feet.The dominant foot has more efficient horizontal extension without load and better buffering function in the vertical direction with loads,while the non-dominant feet perform a more adequate weight-bearing and extension function vertically with larger load.It is suggested that unilateral injury feet should not be given too much load,and it is inappropriate to select a single foot to represent and evaluate the func-tion and injury risk of the double feet in loaded walking.

Objective To investigate the relationship between plantar pressure and plantar sensation in people with different foot types and provide theoretical references for injury evaluation and sports recovery in patients with flat feet.Methods Recruited participants were initially screened using a three-dimensional(3D)foot scanner.They were divided according to the arch index as follows:16 in the normal foot group and 16 in the flat foot group.Plantar pressure and sensation tests were performed in different groups using the Footscan high-frequency plantar pressure test system and the Semmes-Weinstein monofilament test,respectively.The test results were analyzed for statistical descriptions and correlations.Results The plantar pressure impulses of the left and right arches and the medial area in the flat foot group increased significantly compared with those in the normal foot group(P＜0.05).The plantar sensory thresholds of the first metatarsal bone and arch position in the flatfoot group were lower than those in the normal foot group(P＜0.05).There was a significant positive correlation between left foot sole sensation,right foot arch position,and plantar pressure in the flat foot group.Conclusions The structural features of reduced arches and excessive valgus in people with flat feet result in increased plantar pressure impulses and lower thresholds of plantar sensory sensitivity in the arch and medial heel positions.Meanwhile,there is a correlation between plantar sensation and plantar pressure;the greater the load of plantar pressure,the lower the threshold of plantar sensation.