Objective Based on multi-objective optimization,a design method for Voronoi bionic porous scaffolds tailored to different degrees of bone defects was proposed.Methods First,the effects of design parameters on mechanical and biological properties of the scaffolds were investigated.The response surface models were then established respectively for the design parameters and performance indicators(specific surface area,elastic modulus,yield strength,and permeability).Using a cubic scaffold with side length of 15 mm as an example(assuming a corresponding bone defect of the same dimension),multi-objective optimization of the scaffold was finally conducted using the non-dominated genetic algorithm-Ⅱ algorithm,while considering the elastic modulus and permeability ranges of bone tissues as performance constraints.Results The degree of anisotropy in Voronoi scaffolds was influenced by the number of seed points,while the size and scaling factors of the scaffolds exclusively impacted the rod diameter and rod length.Using the design method of this study,the optimal scaffold with specific defect size satisfying mechanical and biological properties was designed.The optimal scaffold meeting different strength requirements was designed by adjusting the yield strength to change the utopia point.Conclusions A design method for Voronoi bionic porous scaffolds based on multi-objective optimization is proposed.This method can be applied to bone defects at varying degrees and provides a new idea for the personalized design of bone tissue engineering scaffolds.

Objective To analyze the electromyography(EMG)characteristics of high-level male speed climbers using Tomoa skip technique,and provide a theoretical basis for the determination of special strength training methods and means.Methods Ten male speed climbers at national first level or above were recruited,and their kinematics and surface EMG signal data using Tomoa skip technique during climbing the official route were collected.Results For using Tomoa skip technique,the order of the main muscle contribution rate for high-level male speed climbers was biceps brachii,triceps brachii,flexor digitorum superficialis,latissimus dorsi,anterior tibial,vastus lateralis,gluteus maximus,medial head of gastrocnemius muscle.The sum of all muscle contribution rates of the left side,the contribution rate of biceps brachii and triceps brachii were significantly lower than that of the right side(P＜0 05).The contribution rate of medial head of left gastrocnemius muscle was significantly higher than that of right side(P＜0.05).The level of activation of the left biceps brachii was significantly lower than that of the right side(P＜0.05).The co-contraction indexes of left elbow joint and ankle joint,right elbow joint and ankle joint were 0.93±0.21,1.33±0.14,0.72±0.10,2.08±0.59,respectively.The co-contraction level of the left elbow joint and ankle joint was significantly higher than that of the right side(P＜0.05).Conclusions High-level male speed climbers using Tomoa skip technique showed obvious EMG characteristics,and the contribution rate of the upper limb muscles and latissimus dorsi were higher than that of the lower limb.The activation mode of elbow joint was dominated by biceps brachii,and that of ankle joint was dominated by anterior tibial muscle.There exsited differences between the left and right limbs in coordinated movement modes.The difference of contribution rate and activation level of the upper limb between the left and right side was more than that of the lower limb.

The increasingly widespread application of artificial intelligence(AI)technology in the field of sports biomechanics has provided more effective technological support for competitive sports science to help athletes improve their performance.Using AI technologies and methods to obtain athletes' biomechanical data,analyze the biomechanical characteristics of movement techniques,design training plans,adjust tactical strategies,and prevent sports injuries has become an integral part of high-level competitive sports.This paper summarizes the current applications of AI technology in sports biomechanics through a literature review,including its applications in movement technique analysis for performance enhancement,tactical analysis,and sports injury prevention.The aim is to provide new ideas for further promoting the application of AI technology in sports biomechanics,offer new methods and means for competitive sports science and technology,and create more possibilities for the development of AI technology itself.

Objective The combined entropy weight technique for order preference by similarity to an ideal solution(TOPSIS)and rank sum ratio(RSR)methods were utilized to rate the protective performance of ice hockey helmets,and the effectiveness and influencing factors of the rating system,as well as the relationship between protective performance and purchase price were explored.Methods The linear acceleration data during impact drops of twenty-four ice hockey helmets were collected using a uniaxial accelerometer in a collision test machine after low and ambient temperature treatments.The protective performance of ice hockey helmets was rated using the STAR model combined with the entropy weight TOPSIS and RSR methods.One-way ANOVA or the Kruskal-Wallis H test was employed to assess the differences in protective performance among helmets across different grade groups.The correlation between different indicators was analyzed by Pearson's correlation coefficient.Results The comprehensive protective performance ratings of the CCM TACKS 310,IBX,BAUD,and WARRIORS COVERT RS PRO helmets were classified as poor,whereas the BAUER REAKT 150,HYPERLITE,and REAKT 200 helmets were rated as excellent.The remaining helmets were rated as moderate.There was a moderate to high positive correlation between the ambient temperature STAR(A)and Rowson's STAR values,the comprehensive Ti and low temperature Ti,the comprehensive T,and ambient temperature Ti(P＜0.05).The comprehensive Ti satisfied the homogeneity of variance(P＞0.05)and exhibited significant differences among groups(P＜0.05).Significant differences were found in the low temperature indicators among different groups(P＜0.05),and their weight coefficients ranked among the top three.The ambient temperature indicators were not affected by the protective performance grade(P＞0.05).A weak positive correlation existed between the comprehensive Ti and purchase price(P＜0.05).Conclusions According to the energy absorption test protocol,the combined entropy weight TOPSIS and RSR methods can efficiently rate the comprehensive protective performance of ice hockey helmets.The effectiveness of using low temperature indicators for the comprehensive evaluation and rating of ice hockey helmet protective performance is superior to that of ambient temperature indicators and purchase price.Consumers are advised not to use price as a criterion for evaluating the comprehensive protective performance of ice hockey helmets.

Objective To investigate the effects of transcranial direct current stimulation(tDCS)combined with resistance training on the performance of college students completing pull-ups,and explore the potential mechanisms underlying the effects of training intervention from the perspective of neuromuscular activity control.Methods A total of 25 male college student volunteers were randomly divided into the tDCS combined with resistance training group(experiment group)and resistance training group(control group).Twelve subjects in the control group received a lat pull-down strength training intervention lasting for 8 weeks,with 4 sets of 12 movement repetitions each,3 times per week.Thirteen subjects in the experimental group received a 20-minute tDCS before the lat pull-up resistance training intervention.Lat pull-down isometric maximal voluntary contraction(MVC)force,lat pull-down maximal repetitions under 80％one-repetition maximum(1RM)loading,and conventional pull-up exercise were tested before and after the training intervention.Surface electromyography(sEMG)signals of the main exertion muscles of the upper limb were recorded during the pull-up exercise test.Results After the training intervention,the number of pull-ups completed by the experimental group and control group increased by 1.74 times and 1.42 times,respectively.Subjects in both groups showed significant improvements in their MVC and lat pull-down maximal repetitions under 80％1RM loading.However,there were no statistical differences in these indicators between groups.Activation levels of the agonist muscles brachioradialis,posterior deltoid,and pectoralis major were significantly decreased after the training compared to those before training for both groups.In addition,the coactivation level of the antagonist triceps brachii muscle in the experimental group significantly decreased from 0.50±0.22 to 0.37±0.09 after the training,while there was no significant change in the control group before and after the intervention.Conclusions Eight-week tDCS combined with resistance training and resistance training alone can significantly improve the pull-up performance of college students,which may be related to the fact that both types of training can significantly improve the active muscle contraction capacity.Combined with resistance training,tDCS is more effective in decreasing the coactivation level of triceps brachii during pull-ups and increasing the contraction efficiency of elbow joint muscles.

Objective To analyze the biomechanical responses after small incision lenticule extraction(SMILE)based on personalized biomechanical parameters of the human eye.Methods Through the results from the correlation analysis between corneal stromal elastic modulus and biomechanical parameters,the cornea elastic modulus was predicted and the material parameters were obtained.Based on clinical measurement data,52 personalized myopic human eye models were reconstructed to analyze the corneal biomechanical response after SMILE.Results The biomechanical response of the cornea varied from patients,and the vertex displacement and stress of the corneal surface increased or decreased after SMILE.On average,when residual stromal thickness(RST)ranged from 278 μm to 332 μm and IOP was 16-20 mmHg(1 mmHg=0.133 kPa),the change of vertex displacement and stress on the corneal surface after SMILE were less than those under IOP=11-16 mmHg.Under RST＞332 μm and IOP=11-16 mmHg,the corneal biomechanics was relatively stable.In addition,the corrected diopters of patients increased,and the deformation of corneal surface after SMILE was more drastic.Conclusions RST and IOP are important factors influencing corneal biomechanics.The material parameters of corneal tissues were predicted based on corneal biomechanical parameters.The cutting profiles and surgical parameters of SMILE may be optimized through analyzing the surgical effect after refractive surgery by reconstructing personalized finite element model of human eyes.

Objective To assess the motor function of school-aged children with congenital muscular torticollis(CMT),and analyze the spatiotemporal parameters of their walking motion as well as the kinematic parameters of the trunk and lower limbs,so as to explore the potential long-term impact of CMT on the growth and development of children.Methods Using three-dimensional(3D)gait analysis technology,the gait of children with CMT was evaluated in detail and compared with that of normal children.The motion angles and ranges of the trunk,pelvis,hip,knee,and ankle joints,along with spatio-temporal parameters,were analyzed.Thirty-one children with CMT aged 6-12 years were recruited into the torticollis group,and 31 normal children of the same age range were included in the control group.The data of the torticollis group were divided into the healthy side and the affected side based on the side of the torticollis.Statistical analysis was performed among the three groups to calculate the differences in kinematic and spatio-temporal parameters.Results Compared with nomal children of the same age in the control group,significant differences were observed in the affected and unaffected sides of the torticollis group in terms of stride length,gait speed,percentage of support phase time,average ankle inversion angle during the swing phase,average ankle inversion angle during the support phase,average foot orientation angle during the support phase,average ankle internal rotation angle relative to the tibia during the stance phase,average knee valgus angle during the stance phase,average shoulder joint elevation,and shoulder joint height at landing.Specifically,the torticollis group had significantly lower stride length,gait speed,ankle inversion angle,knee valgus angle,and foot eversion angle in both the affected and unaffected sides compared to the control group,while the percentage of support phase time and the internal rotation angle of the foot relative to the tibia during the stance phase were higher than those in the control group.Conclusions For school-aged children with CMT,there are still residual manifestations of overall motor development abnormalities.These abnormalities also affect the non-affected side.Children with CMT have a relatively high risk of developing uneven shoulders,their overall walking efficiency is lower than that of normal children of the same age,and they exhibit lower limb motor abnormalities such as insufficient ankle joint stability.

The incidence of vascular diseases is extremely high and mechanical stress plays an important role in vascular remodeling.Reactive oxygen species(ROS)at physiological levels modulate cell signaling while excessive ROS trigger oxidative stress and induce injury.The types of mechanical stresses in the vascular system and the sources of ROS are summarized.Besides,the roles and mechanisms of mechanical stress-induced oxidative stress in vascular diseases are discussed.This review will facilitate a deeper understanding of vascular activity and disease development at the molecular level,provide potential targets for treating vascular diseases.In addition,there are still research gaps on the mechanism of oxidative stress induced by mechanical stress in vascular diseases.Therefore,the potential research direction of mechanical stress-induced oxidative stress in the vascular system is also predicted,with the aim to promote the development of mechanobiology to a certain extent.

Foot torsion stiffness refers to the foot's ability to resist deformation when subjected to torsional forces,and such characteristics play a crucial role in the prevention of sports injuries and design of athletic footwear.This review systematically summarizes the biomechanical research progress of foot torsion and shoe torsion,as well as the research and application of multi-segment foot models in foot-shoe torsion.The findings indicate that foot torsional stiffness significantly impacts lower limb kinematics,kinetics,and athletic performance.Optimizing this stiffness can improve stress distribution,reduce injury risk,and enhance performance.The future researches should focus on refining measurement techniques to enhance reliability and efficiency in clinical applications,providing a scientific foundation for sports injury prevention and footwear design.

Objective To investigate the effects of 16-week Tai Chi exercise on muscle strength,plantar tactile sensation,kinesthesia,and postural control of older adults at different ages.Methods Thirty-nine older adults were divided into 60-75-year-old group(n=24)and the 76-90-year-old group(n=15),and both groups received Tai Chi practice for 16 weeks.The muscle strength,plantar tactile sensation,kinesthesia,and center of pressure root mean square(CoP-RMS)were measured before and after practice.Results After 16 weeks of Tai Chi exercise,the fifth metatarsal head tactile sensation and ankle dorsiflexion/plantarflexion kinesthesia thresholds decreased in the 76-90-year-old group.However,there was no significant change in the 60-75-year-old group.The CoP-RMS in the medial/lateral direction decreased in the 60-75-year-old and 76-90-year-old group.Conclusions After 16 weeks of Tai Chi exercise,muscle strength,plantar tactile sensation,kinesthesia,and postural control were improved.Especially for older adults aged over 75 years,Tai Chi exercise improved their plantar tactile sensation,kinesthesia,and postural control to a greater extent.Tai Chi practice provides a suitable and effective exercise form for older adults over 75 years.