USING IMPACT TESTING METHOD TO ESTIMATE THE ENERGY ABSORBED BY INSOLES IN SPORTS SHOES

The purpose of this study was to estimate the energy absorbed by insoles in typical sports shoes with impact testing method. Three commercial sports shoe were used in this study. Totally eight impacts with 1.8 to 6.1 joules of potential energy were performed onto the heel region of the shoe. Peak acceleration of the striker was measured with accelerometer attached to the striker during impact. According to the linear regression equations between mean peak acceleration and impact energy for without and with insole conditions, the energy absorbed by insole under different impact energy (2-6 joule) was c.alculated'. The new approach carried out in this study to calculate the energy absorbed by insoles could assess the role of insoles in the cushioning property of sports shoes

TEST-RETEST RELIABILITY OF PAIRED PREFERENCE TEST FOR THE WEIGHTED SHOES

The purpose of this study was to examine the test-retest reliability of paired preference test for the weighted shoes. Forty participants were recruited and instructed to put on the weighted shoes and choose the preferred one after completing four paired comparisons. During the tests, participants were blind of any information from the shoes. All the participants were invited to repeat the same procedure one week after the first session. The results in first session showed that thirty-two (80%) out of the forty participants preferred Shoe D or E, which centre of mass was close to the rear end of the shoe. The greater intra-class correlation coefficient (ICC=0.81) represents the perfect test-retest reliability of the paired preference test. The test protocol designed in this study could apparently reduce the numbers of the paired comparison under the characteristic of the testing shoe varied systematically, for example the weighted shoes used in this study

VARIABILITY OF BARBELL TRAJECTORY DURING SNATCH FOR AN ELITE YOUNG FEMALE WEIGHTLIFTER

The purpose of this study was to investigate the variability of the barbell trajectory for an elite young female weightlifter. One high speed camera (120Hz) was used to film the barbell trajectories of a female lifter during snatch. The subject was asked to lift different barbell mass from 65 to 80 kg (fourteen lifts in total), and thirteen successful lifts were analyzed. The barbell trajectories and movement pattern of different lifts were similar to the results of previous studies, and the barbell paths almost were overlapping for the heaviest four successful lifts. The coefficients of variation (CV) of four kinematic parameters of barbell trajectory were smaller than the results of previous studies. It can be concluded that this female weightlifter has a stable pattern of barbell trajectory under different barbell mass lifting

THE RELATIONSHIP BETWEEN THE BARBELL TRAJECTORIES OF SNATCH AND BCH ANGLES

The purpose of this study is to investigate the relationship between the barbell trajectories of snatch and the angle between the projection vector of 7th cervical spinous process (C7) to barbell and the projection vector of C7 to hip joint in the sagittal plane (BCH angles) in different events. The ten weightlifters were divided into two groups according to their barbell trajectories (BT was categorized into the backward barbell trajectories, and the FT was forward). The results show that the BCH angles at PB and MF in BT are smaller than FT. The weightlifers with the backward trajectories usually make better performances. After analysis, we find out that the backward trajectories would reduce the BCH angles. The present study suggests that catching the bar with backward trajectories and smaller BCH angles at PB and MF are perhaps a better technique for snatch

USING BARBELL KINEMATICS TO PROVIDE THE COACH WITH THE FEEDBACK FOR THE SNATCH

The purpose of this study was to use three dimensional kinematics of the barbell to provide the coach with quick feedback for the snatch technique of an elite Taiwanese female weightlifter. Three high speed cameras were used to simultaneously record the barbell movements with film frequency of 200 Hz. The horizontal dispalcement-velocity relationship of the barbell seemed to have varied in a certain range while lifting a 95kg barbell. Based on these results, it was recommended the lifter attempt 95kg for her first attempt in the competition. In conclusion, the barbell kinematics is a quick and easy approach to provide the coach with feedback for the snatch. The information of trajectory and movement characteristics of the barbell could provide the coach and the lifter to assist in improving the lifter’s snatch technique

PREFERENCE TEST OF THE WEIGHTED SHOES

The purpose of this study was to use paired comparison approach to test the weighted shoe preference of the subjects. Forty subjects were recruited to put on five different weighted shoes and choose the preferred one after completing four paired comparisons. During the test, subjects were blind of any information from the shoes. The results showed that thirty-two (80%) out of the forty subjects preferred Shoe D or E, which centre of mass was close to the rear end of the shoe. Significant difference was found in shoe preference between the males and females (?24=10.500, p=.033), while was not found between the lighters and heaviers (?24=5.583, p=.233). The mechanism of the gender effect on the preference decision are unclear. The results of the weighted shoe preference test could be applied to athlete training or rehabilitation shoe design to be comfortable for the users

INFLUENCES OF THE SHOE SOLE HARDNESS AND SPEED ON STRIDE FREQUENCY AND STRIKING POSITION VARIABILITY DURING TREADMILL RUNNING WITHOUT AWARENESS OF SPEED CHANGE

The purpose of this study was to investigate the influences of wearing soft or hard soled shoe on the runner’s stride frequency and striking position variability, while the runner was not aware of the treadmill speed changing by visual or auditory information. The positions of the right ankle markers on the twenty subjects were captured to determine the stride frequency and striking position variability from ten strides at different speeds during six minutes of treadmill running. The results showed that the runner’s stride frequency significantly increased as the treadmill speed increased (

INFLUENCES OF THE SHOE SOLE HARDNESS ON THE PERCEPTION OF BELT SPEED CHANGE DURING TREADMILL RUNNING

Twenty-three subjects wore shoes with hardness of shore 45C and 70C to run on a motor-driven treadmill in this study. During the testing session, the console of the treadmill was covered by a black cloth and each subject must wear an earphone to isolate the external sound, in order to avoid the subject noticing the speed change of the treadmill. The runner was asked to say “Yes” of signal if he was aware of changing of the belt speed. The results showed that wearing the soft soled shoe, the mean correct and wrong responses are 2.3(±1.4) and 4.3(±3.6) times, respectively. With the hard soled shoe, the mean correct and wrong responses are 2.3(±1.2) and 4.8(±3.5) times, respectively. In conclusion, the shoe sole hardness did not affect the bad speed change perception of the subjects during treadmill running

BIOMECHANICS OF STOP-JUMP LANDING AND IN-LINE SKATING JUMP LANDING

The purpose of this study was to identify the movement characteristics of lower extremities during stop-jump landing and in-line skating jump landing. Two subjects were asked to perform three jump landing tasks: stop-jump with barefoot (BF), stop-jump with ankle constrain (AC) and jump with in-line skating boots (IS). Landing movements in sagittal plane were recorded by one high speed camera. The activation of four muscles during landing was measured by EMG system. The kinematic results showed that most variables were significantly different between the three jump landing tasks, except for knee angle at ground contact. More activated rectus femoris and smaller knee flexion acceleration found in IS have been considered to be related the ACL injury. It can be concluded that in-line skating jump landing might have higher lower limbs injury risk

THE DISCRIMINATION OF BARBELL WEIGHT FOR WEIGHTLIFTERS

Ten college weightlifters were recruited in this study. The standard barbell weight (Ws) of each participant was set at 80% of personal best snatch record. The test barbell weights that include Ws, Ws+-1kg, Ws+-2kg, and Ws+-5kg were given randomly, then each lifter was asked to identify the difference between the test weight and standard weight. The discrimination was over 86% when the test weight was Ws+-5kg. For the test weight equal to the standard weight, the discrimination was significantly less than that of other test weights (p less than 01). Based on the results, the weightlifter seems to have good discrimination in the barbell mass at the difference of 5 kg. It seems that they could not be aware of the slight difference (ex: less than 2kg) of barbell mass by 80% of their best snatch record