APPLICATION OF PLANTER FORCE MEASUREMENT IN EVALUATION OF SOCCER SHOES

Normal soccer shoes are manufactured using homogenous material for midsole. Soccer game requires the players to tackle the soccer ball as quickly as possible. It was thought that a dual density material design of the midsole may provide better control to the foot. To study this question, we developed prototype soccer shoes with two different midsole designs. One was made up by homogeneous EVA material (Shore A 95) and the other (S2) was made up by the same material except for the forefoot area where a relatively soft EVA material (Shore A 85) was used. Both shoes have similar structure and material in all other aspects including the studs. The purpose of this study was to compare the plantar force generated during 30-m sprint wearing soccer shoes with homogeneous and dual density midsole designs

TAI CHI INCREASED BODY STABILITY AMONG THE ELDERLY UNDER THE DUAL TASK CONDITION DURING STAIR ASCENT

Our work aimed to find out whether Tai Chi (TC) exercise could improve body stability among the elderly under a physical-cognitive dual task (DT) condition during stair ascent. 15 elderly persons who regularly exercised TC and 15 no exercise (NE) participants were asked to walk ascending stairs under single task (ST) and DT conditions in this study. The results showed the TC group had a lower lateral impulse and center of mass-center of pressure (COM-COP) ap/ml separation under the DT condition; Compared with the ST condition, the TC group increased foot clearance, the NE group increased their lateral impulse and COM-COP ml separation under the DT condition. Under DT, body stability decreased among the NE group, but the TC group had better body stability during stair ascent under both ST and DT conditions

COULD TAI CHI EXERCISE IMPOVE STABILITY IN ELDERLY? STRATEGIES OF STEPPING OVER OBSTACLES

Stepping over obstacles challenges stability and is a leading cause of falls in older adult populations. The purpose of this study was to evaluate the obstacle-crossing strategies of long-term Tai Chi (TC) practitioners and exercise walkers. Thirty healthy older women (average age: 65.7 years) with either TC (n=15) experience (average experience: 8.2 years) or walking exercise (n=15; average experience: 8.8 years) participated in this study. We used three trial conditions: 1) normal walking, 2) crossing a 15cm (20% of leg length) obstacle, and 3) crossing a 23cm (30% of leg length) to assess obstacle-crossing strategy. Results showed Individuals with a TC background crossed the obstacle significantly faster with a significantly longer step relative to the exercise walkers; plantar pressure profiles between the two groups also differed. Our results suggest that obstacle-crossing strategies were affected by the type of long-term exercise

THE KINEMATICAL CHARACTERISTICS OF THE LOWER EXTREMITIES DURING TAl CHI CHUAN EXERCISE

There is broad consensus that Tai Chi Chuan exercise can improve the balance control and muscle strength of the lower extremities. However, the mechanism used to promote that balance control and muscle strength is still unclear. The purpose of this study is to provide evidence of the kinematical characteristics of the lower extremities during Tai Chi Chuan exercise and explain the way in which they benefit balance control and muscle strength A female elite Tai Chi Chuan master was recruited to participate in the study. Five typical movements were selected: Brush Knee and Twist Steps, Step Back to Repulse Monkey, Wave Hand in Cloud, Kick Heel to Right, and Grasping the Bird's Tail. For each typical movement, three trials were recorded and digitized with a video motion analysis system. Kinematical parameters including the step length, the base of gait, angle of gait, mean ankle complex flexion, range of motion, range of motion rotation, and mean knee flexion, range of motion were calculated and analyzed. The results showed that compared to the normal gait, Tai Chi Chuan movements had a longer step length, a wider base of gait, and a larger angle of gait. The small angles and large range of motion existed in both the ankle complex and the knee joint. These kinematical characteristics may help to maintain stable posture and improve the muscle strength of the lower extremities during the performance of Tai Chi Chuan exercise

Effect of approach run velocity on the optimal performance of the triple jump

Purpose: The purpose of this study was to determine the effect of horizontal and vertical velocities at the landing of the last step of approach run on the performance and optimal phase ratio of the triple jump. Methods: Three-dimensional kinematic data of 13 elite male triple jumpers were obtained during a competition. Computer simulations were performed using a biomechanical model of the triple jump to determine the longest actual distance using the optimal phase ratio with altered horizontal and vertical velocities at the landing of the last step of approach run. Results: The actual distance obtained using the optimal phase ratio significantly increased as the horizontal velocity at the landing of the last step of approach run increased (p = 0.001) and the corresponding downward vertical velocity decreased (p = 0.001). Increasing horizontal velocity at the landing of the last step of approach run decreased optimal hop percentage and increased optimal jump percentage (p = 0.001), while decreasing corresponding downward vertical velocity increased optimal hop percentage and decreased optimal jump percentage (p = 0.001). Conclusion: The effects of the velocities at the landing of the last step of approach run on the optimal phase ratio were generally small and did not qualitatively alter optimal techniques

THE CHARACTERISTICS OF THE PLANTAR PRESSURE CENTER DURING TAl CHI EXERCICE

The purpose of this study was to describe and quantify the plantar pressure distribution characteristics during Tai Chi (TC) exercise. Sixteen elite TC masters participated in this study. The Pedar-X insole system was used to record the plantar forces during practicing the five typical TC movements and during normal walking respectively. Results showed that in TC movements, the locations of the centre of pressure (COP) were more medial and posterior at initial contact (p < 0.05), while more medial and anterior at end contact with the ground (p < 0.05). The range of motions (ROMs) of COP were significantly wider (P < 0.05) in mediolateral direction in forward, backward, and sideways TC movements. The ROM was significantly larger (p < 0.05) in anterposterior direction in forward TC movement when compared with normal walking

BIOMECHANICAL CHARACTERISTICS OF SQUATTING WEIGHT LIFT: A CASE STUDY

The purpose of this study was to provide biomechanical data analysis of the squatting lift skill of an elite weight lifter. The performance of the athlete (X. Z.) was studied by means of 3-D fixed video testing and data analysis. Some key parameters of the body and barbell in every important phase were provided in this article. The objective was to profile a sample of biomechanics pattern of this technique with these parameters. The results of the study showed that the subject (X. Z.) performed the squatting and propping skill too long to complete catching barbell movement after the barbell reached the maximum speed. However the attempt was surprisingly successful. This proved that the strength of the lower limbs was sufficiently strong enough to complete the move

EFFECTS OF EXERCISE ON ANKLE PROPRIOCEPTION DURING SIXTEEN WEEKS OF TRAINING AND EIGHT WEEKS OF DETRAINING IN OLDER ADULTS

This study evaluates the ankle proprioception in older adults. Sixty women (age 62.1±4.3yr) were randomly assigned to three groups to undergo a 16-week training (one group practice Tai Chi,one group practice brisk walking and one group reading) and 8-week detraining program. Proprioception of ankle plantarflexion (PF), dorsiflexion (DF) were measured, better proprioception is defined as being able to detect a smaller degree in joint angle. The results showed that degree PF and DF changes earlier and were smaller in TG than in BG in training; degree of PF and DF declined in all groups during the detraining, but TG exhibited a significant difference with pre-training data. So Tai Chi can more effectively improve and maintain ankle proprioception as well as prevent fall in old age. However, the extent of benefit depends on the regularity of training in older adults

BIOMECHANICS ANALYSIS OF SNATCHING SKILLS IN WOMEN TOPNOTCH WEIGHT LIFT -A CASE STUDY

This study analyzed the biomechanics characteristics for a Chinese subject's 120 kg snatch skills act mainly through photographing measuring. The result showed: the barbell vertical changes were apparent, the barbell's vertical speed reached its maximum of 1.98 m/s when the barbell was 0.72 s away up the ground, and the barbell reached its highest point of 1.05 m when it was 1.0s away up the ground. It was concluded that the subject's skill showed the characteristic of quick breaking pull

ELEMENTARY RESEARCH ON THE MOST SUITABLE MODE FOR THE ARCHERS OF THE SHAN DONG TEAM

INTRODUCTION: Archery is an ancient sport. In recent years, the development of archery in China has been quite rapid. The performence of this sport in Shan Dong has also rapidly increased, but it is rare for archers` techniques to be quantitatively analyzed. Therefore the movement strcture, kinematic features and influence on the performence of 6 archers on the Shan Dong team were comprehensively compared and analyzed in order to raise their technical level .The best movement techniques were found and combined in the most suitable mode of these six archers. According to this mode, their techniques were improved individually in training .The more rational movement techniques were performed, followed by an exploration of new ways of scientific training in archery. METHODS: Thirty-six arrow shots of these six archers of the Shan Dong team were analyzed, and the data were processed by the more advanced video analysis system - Bewegungs Analysis System: Pentium 586 computer; 21inch SAMSUNG advanced color monitor (1024%1024); Panasonic Video Cassette Recorder (AG- 7355); the video tape was recorded with time code; the software program to be provided by Germany. The interval between the frames was 0.02 second. The digital filtering method was used for data smothing and a cutoff frequenty of 3 hz was adopted. In measuring, x axis: the direction perpendicular to the target; y axis: the direction perpendicular to the horizontal plane; z axis: the direction of paralleling the target. RESULTS: 1. A comparison and analysis of six archers in each phase period 1.1 The average time for an arrow to be shot by each varies greatly (from 4.812s to 10.956s). The average time for an arrow to be shot by the same archer is relatively stable. The movement rhythm of the six archers is not the same. 1.2 The shooting time of arrows hitting the ten-point ring is ordinarily from 4.78s to 7.84s, and the aiming time is from 2.46s to 5.60s.The shooting time of arrows hitting the eight-point ring is under 4.32s, and the aiming time is under 2.24s. 2. A comparison and analysis of the kinematic features of these six archers was made. CONCLUSION AND SUGGESTION: 1.The movement rhythm of Li Changjun, Tang Huan and Zhu Maodong is relatively fast, The movement rhythm of Xin Lei and Li Ming is relatively slow. The movement techniques of Li Meng and Zhu Maodong in forcing to release period are a bit similar. The movement techniques of Xin Lei and Sun Wei in forcing to release period are a bit similar. 2. The best movement techniques of each can be combined in the most suitable mode to train the archers. 3. In training, the movement technique of some of the archers should be improved with rational technique features. REFERENCES: Jiang Qian et al. (1993). A Study of Elite Chinese Archers’ Aiming Skills. Sports Science of China 1