ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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PREFERENCE TEST OF THE WEIGHTED SHOES
Get PDFThe 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
A 6-COMPONENT PADDLE SENSOR TO ESTIMATE KAYAKER’S PERFORMANCE: PRELIMINARY RESULTS
Get PDFThe purpose of this study was to measure the paddle shaft-hand interaction while an athlete paddled a kayak ergometer. The paddle shaft was specifically equipped with two 6-component force sensors to measure the contact force between the athlete’s hands and the paddle shaft. In order to minimise the error of the data collected, this new instrumentation was specifically calibrated for this experience. Preliminary results suggested that this new instrumentation provided data of high interest to improve our knowledge of the propulsion and recovery phases while kayaking an ergometer. In the future, this innovative instrumentation could be used during on-water sessions
THE ASSOCIATION BETWEEN UNILATERAL BALANCE AND KICKING
Get PDFBalance is a common coaching cue and technical factor associated with kicking in the football codes. The aim of this study was to compare balance ability and maximal kick performance for the punt kick. Fifteen elite junior Australian Football players performed maximal punt kicks with their preferred and non-preferred legs with foot and ball speed calculated using VICON. Balance ability was assessed unilaterally during three 20 s standing tasks on a force plate using centre of pressure range and medio-lateral force standard deviation. No relationship was found between balance ability and kick performance, similar to soccer kicking. Future work should explore balance in more kick-specific tasks
RELATIVE FORCE AND PAP IN SWIMMING START PERFORMANCE
Get PDFFirstly, it was studied the relationship between relative force (Frel) of the lower limbs in a isotonic Lunge test, with the performance in a swimming kick start (SS). Afterwards, were applied two Postactivation-Potentiation (PAP) specific warm ups in order to analyze their effect in performance considering the Frel of the subjects. Trained swimmers (n=14) volunteered in this study. Pearson product-moment correlation coefficients were used to verify the relationship between relative force and kinematic variables of a SS. Results revealed high correlation between relative force and performance in SS (Dive Distance: R2=0.872,
KINETIC AND KINEMATIC FEATURES OF COUNTERMOVEMENT AND SAUTÉ JUMPS IN CLASSICAL BALLET DANCERS
Get PDFThe purpose of this study was to investigate how the external rotations of lower limbs influence the performance of ballet dancers in jumps. Four ballet dancers with high technical proficiency were recruited for a test, they performed three attempts the countermovement and sauté jump. Two force plates were used to determine ground reaction forces. Six cameras were used to collect the kinematic data. It was analyzed the peak of knee flexion, peak of ground force reaction and jump height. The performance in countermovement and sauté jump tests was compared through box plot analysis. In conclusion, even with a lower degree of knee flexion, dancers can produce higher jumps and more ground force reaction on countermovement jump. The results suggest that the attention focus when jumping is an important determinant of jump performance
THE RELATIONSHIP BETWEEN FORCE PRODUCTION DURING ISOMETRIC SQUATS AND KNEE FLEXION ANGLES DURING LANDING
Get PDFThe current study quantified the relationship between force production during isometric squats performed at different external knee flexion angles (40, 60, 80, and 100 degrees) and initial and peak knee flexion angles during landing. A total of 18 male and 18 female recreational/collegiate athletes completed a jump-landing-jump task and four maximal isometric squats at different knee flexion angles. Significant correlations were observed between peak force production during isometric squats and initial and peak knee flexion angles during landing for females, but not for males. For females, decreased isometric strength during squats was associated with decreased knee flexion during landing. For males, isometric strength alone may not be sufficient to explain differences in knee flexion during landing. Future studies are warranted to study the effect of postural-specific strength training on landing mechanics in females
BALANCE VARIABILITY DURING THE PYRAMID EXECUTION IN ACROBATIC GYMNASTICS
Get PDFThe objective of this study was to analyse the relationship between intra-trial variability in balance scores obtained via a force platform and acrobatic gymnasts’ pyramid scores provided by a qualified and experienced judge. Twelve acrobatic gymnasts grouped in pairs performed five successful straddle lever pyramids on two force platforms with one foot on each platform. The variability of path length of the centre of pressure of each foot was examined to analyse the balance of the pyramid. The variability of path length was negatively correlated with pyramid score in both legs, non-preferred (rho = -0.706 [very large]) and preferred leg (rho = -0.530 [large]). The results suggest a relationship between intra-trial variability and pyramid performance
THE EFFECT OF SIDE STEP ON LOWER EXTREMITY BIOMECHANICS DURING BLOCK LANDING IN FEMALE VOLLEYBALL PLAYERS
Get PDFThe purpose of this study was to examine the effect of block and side step block on lower extremity biomechanics during landing in female volleyball players. Eight female university volleyball players participated in this study. The kinematic and kinetic data were collected by eight Vicon cameras (250 Hz) and two force plates (1000 Hz). The Visual 3D software was used to analyze the kinematic and kinetic of block and side step block landing variables. The results showed a significantly higher knee extensor moment during side step landing than the block landing at the time of peak vertical ground reaction force and peak joint moment. It was concluded that female players displayed greater knee extensor moment during the side step before block landing that may increase the loading on the knee
DOSE FASTER HOPPING FREQUENCY IMPROVE RESPONSE TIME AND KICKING SPEED IN TAEKWONDO ROUNDHOUSE KICK?
Get PDFThe purpose of this study was to investigate the effect of rhythmic hopping frequency on the response time and kicking speeds in Taekwondo roundhouse kick. Eleven elementary and middle-school athletes voluntarily participated in this study. They performed five roundhouse kicks at three different hopping frequencies (normal, 15% faster than normal, and 15% slower than normal) and no hop condition. Results indicated that the 15% slower hopping frequency induced a significantly longer response time than the 15% faster frequency. The 15% faster frequency resulted in faster maximum kicking speed than normal frequency did, while there was no difference in contact kicking speed. Partially the faster hopping frequency would be beneficial to kicking performance
STRETCH-SHORTENING CYCLE FUNCTION OF THE KNEE EXTENSOR MUSCLE-TENDON UNIT DURING THE POWER CLEAN
Get PDFThe purpose of this case study was to investigate the stretch-shortening cycle behaviour of the knee extensor muscle-tendon unit during the power clean exercise. Kinematic and kinetic were acquired as a skilled weightlifter performed several repetitions of the power clean at 85% of 1-Repetition Maximum. Knee joint angular velocity, moment, and power time-series during the pull-phase of the power clean were calculated and used to delineate between concentric and eccentric movement phases. The analysis of the kinematic time-series data showed knee extension-flexion-extension movement pattern, whereas the analysis of the kinetic data showed that the movement pattern consisted of dynamic concentric and eccentric sequences, which highlighted stretch-shortening cycle behavior of the knee extensors, and surprisingly also the knee flexor, muscle groups