This study reviews recent publications on the biomechanical causes and treatment of flat foot,through searching PubMed,Web of Science,CNKI,Wanfang and other databases.The reasons for the formation of flat foot include congenital factors and acquired factors,while the treatment methods mainly include orthopedic insoles,physical therapy,surgical therapy and exercise therapy.These methods,to a certain extent,can correct foot structural abnormalities,optimize biomechanical properties and improve foot stability and range of motion.For future research,the advanced imaging and simulation technology will be used for accurate assessment,the application of novel materials and non-surgical therapies will relieve long-term symptoms,genetic researches will promote the development of early diagnosis and personalized treatment,and the use of intelligent orthosis will realize real-time monitoring and dynamic adjustment,to provide more and more effective methods and means for the evaluation,intervention and treatment of flat foot.

Objective The athletic performance and physiological indicators of two top seated cross-country skiers during simulated competitions were analyzed,and the characteristics of exercise intensity and pacing strategies in different terrains were explored,so as to provide a scientific basis for physical fitness allocation and speed rhythm optimization of the athletes.Methods Differential global positioning system and Momentum Technology MT-Sports T2 were used to test athlete A and athlete B with class of locomotor winter 10(LW 10),who were the first and second runners-up of Beijing Winter Paralympic mid-distance cross-country ski race.The athletes' real-time gliding speed and heart rate during five consecutive 15 km cross-country skiing time trials were collected,and the time spent on each section,speed and heart rate changes in each course were analyzed.Results The coefficient of variation(CV)of mean heart rate on uphill and flat terrain sections were significantly correlated with total scores.The average gliding speed and average heart rate as a percentage of maximum heart rate(HRmax)of the athletes in three terrains were significantly correlated with total scores.The correlation between the mean time spent on uphill and flat terrain and total performance was stronger than that between the mean time spent on downhill terrain and total scores.Both athletes used a cumulative acceleration speed rhythm.Conclusions Uphill and flat terrain time are critical to race performance.Athletes adopt a progressive pacing strategy,gradually increasing speed in the first half,maintaining stable output in the mid-race,and finishing the last lap at a high-speed.Heart rates are mainly distributed between 70％-90％HRmax,and balancing high-intensity efforts on uphills with recovery on downhills helps optimize energy expenditure.

Objective To investigate the kinematic patterns of gate-turning techniques in sitting alpine skiing at the Winter Paralympic Games and their impacts on skiing performance.Methods Using drone footage and inertial sensor technology,kinematic data were collected from 11 alpine sit-skiers preparing for the Winter Paralympics.Key technical indicators such as turning radius,skiing speed,and trajectory length were analyzed for their relationship with skiing performance.Results The minimum turning radius during gate turns was(15.80±3.55)m,and turning radius showed a significant positive correlation with skiing time(r=0.40,P=0.02)and trajectory length(r=0.88,P＜0.01).The maximum skiing speed was(16.92±1.60)m/s,which was strongly negatively correlated with total skiing time(P＜0.01).Exit speed was also significantly positively correlated with total skiing distance(P＜0.05).Additionally,single-gate technical characteristics(such as turning radius and speed variation),were strongly reflective of overall skiing performance.Conclusions Optimizing turning radius and minimizing speed loss are critical for improving skiing efficiency.Single-gate kinematic analysis provides a scientific basis for overall technique optimization and offers valuable guidance for training and competition strategy design.

Objective To investigate the kinematic patterns of gate-turning techniques in sitting alpine skiing at the Winter Paralympic Games and their impacts on skiing performance.Methods Using drone footage and inertial sensor technology,kinematic data were collected from 11 alpine sit-skiers preparing for the Winter Paralympics.Key technical indicators such as turning radius,skiing speed,and trajectory length were analyzed for their relationship with skiing performance.Results The minimum turning radius during gate turns was(15.80±3.55)m,and turning radius showed a significant positive correlation with skiing time(r=0.40,P=0.02)and trajectory length(r=0.88,P＜0.01).The maximum skiing speed was(16.92±1.60)m/s,which was strongly negatively correlated with total skiing time(P＜0.01).Exit speed was also significantly positively correlated with total skiing distance(P＜0.05).Additionally,single-gate technical characteristics(such as turning radius and speed variation),were strongly reflective of overall skiing performance.Conclusions Optimizing turning radius and minimizing speed loss are critical for improving skiing efficiency.Single-gate kinematic analysis provides a scientific basis for overall technique optimization and offers valuable guidance for training and competition strategy design.

This study reviews recent publications on the biomechanical causes and treatment of flat foot,through searching PubMed,Web of Science,CNKI,Wanfang and other databases.The reasons for the formation of flat foot include congenital factors and acquired factors,while the treatment methods mainly include orthopedic insoles,physical therapy,surgical therapy and exercise therapy.These methods,to a certain extent,can correct foot structural abnormalities,optimize biomechanical properties and improve foot stability and range of motion.For future research,the advanced imaging and simulation technology will be used for accurate assessment,the application of novel materials and non-surgical therapies will relieve long-term symptoms,genetic researches will promote the development of early diagnosis and personalized treatment,and the use of intelligent orthosis will realize real-time monitoring and dynamic adjustment,to provide more and more effective methods and means for the evaluation,intervention and treatment of flat foot.

Objective The athletic performance and physiological indicators of two top seated cross-country skiers during simulated competitions were analyzed,and the characteristics of exercise intensity and pacing strategies in different terrains were explored,so as to provide a scientific basis for physical fitness allocation and speed rhythm optimization of the athletes.Methods Differential global positioning system and Momentum Technology MT-Sports T2 were used to test athlete A and athlete B with class of locomotor winter 10(LW 10),who were the first and second runners-up of Beijing Winter Paralympic mid-distance cross-country ski race.The athletes' real-time gliding speed and heart rate during five consecutive 15 km cross-country skiing time trials were collected,and the time spent on each section,speed and heart rate changes in each course were analyzed.Results The coefficient of variation(CV)of mean heart rate on uphill and flat terrain sections were significantly correlated with total scores.The average gliding speed and average heart rate as a percentage of maximum heart rate(HRmax)of the athletes in three terrains were significantly correlated with total scores.The correlation between the mean time spent on uphill and flat terrain and total performance was stronger than that between the mean time spent on downhill terrain and total scores.Both athletes used a cumulative acceleration speed rhythm.Conclusions Uphill and flat terrain time are critical to race performance.Athletes adopt a progressive pacing strategy,gradually increasing speed in the first half,maintaining stable output in the mid-race,and finishing the last lap at a high-speed.Heart rates are mainly distributed between 70％-90％HRmax,and balancing high-intensity efforts on uphills with recovery on downhills helps optimize energy expenditure.

Objective To make analysis and diagnosis on backhand twist technique used by player A, who is the leading men’s player of national table tennis team, so as to provide references for improving his backhand twist technique. Methods The three-dimensional kinematics test and analysis were used. The backhand twist techniques of player A and those of player B who has good backhand twist techniques were compared by quantitative data and picture analysis. Results At the stage of swinging racket backward, the racket swing amplitude, shoulder angle and wrist angle of player A were significantly smaller than those of player B. The roll angle of trunk of player A was significantly larger than that of player B. At the stage of swinging and hitting the ball, the shoulder angle, elbow angle of player A were significantly bigger than those of player B, while the increasing amplitude of shoulder angle and elbow angle, as well as the changing amplitude in roll angle of trunk of Lin Guoyuan were significantly smaller than those of player B. At the stage of swinging racket forward, the shoulder angle and elbow angle of player A were significantly bigger than those of player B. The increasing amplitude of shoulder angle and elbow angle, as well as the roll angle of trunk and its changing amplitude of player A were significantly smaller than those of player B. Conclusions The racket swing amplitude of player A was smaller, and the distance between the racket and the ball of player A was close at the end of swinging racket backward stage. During swinging and hitting the ball stage, the hitting point was far from the body, the shoulder joint was not stable enough to support, so that the wrist was used more. The center of gravity was not enough to force forward, and the outburst power was not concentrated. At swinging racket forward stage, player A’s braking was not active enough, which affected the stability of hitting the ball. At hitting the ball stage, the torsion of the trunk was smaller, and the waist power was not concentrated. On the basis of unaffecting the forehand outburst power, player A should slightly adjust his backhand twisting technique, or appropriately increase the the racket swing amplitude and torsion of the body. In the process of hitting the ball, the sequence of outburst power was the waist, the forearm and the wrist.

Objective: To investigate the effect of Wnt3a on osteogenic differentiation of human dental pulp stem cells (DPSC). Methods: DPSCs were subjected to different concentrations of Wnt3a (0, 5, 20, 50 and 100 μg/L) and at seven days after culture the alkaline phosphatase (ALP) activity was tested. Mineralized nodule formation was examined by alizarin red staining. Osteogenic-related gene expression of bone sialoprotein (BSP), osteocalcin (OCN), collagen type Ⅰ (COL-Ⅰ), Runt-related transcription factor-2 (RUNX2) was examined by quantitative real-time PCR (qPCR). Results: After seven days of induction by DPSC, Wnt3a protein could inhibit the ALP activity (concentration 0: 1.076±0.203, 5 μg/L: 0.828±0.118, 20 μg/L: 0.505±0.044, 50 μg/L: 0.499±0.038, 100 μg/L: 0.483±0.060). The expression of OCN in 5 μg/L Wnt3a group (0.092±0.005) was lower than that in culture medium (0.858±0.190)(P<0.05). Alizarin red staining showed that 5 μg/L Wnt3a had no mineralization induction effect on DPSC. Conclusions Wnt3a could inhibit osteogenic differentiation of dental pulp stem cells.