ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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CHANGES IN ACCELERATION PHASE SPRINT BtOMECHANlCS WITH LOWER BODY WEARABLE RESISTANCE
Full text linkWearable resistance (WR) attached to the lower body may be advantageous for sprint acceleration training. The aim of this study was to quantify the kinematic and kinetic changes that occur during the sprint acceleration phase when lower body WR is worn. Radar and Optojump were used to assess fifteen male rugby athletes sprinting over 20 m under three different loading conditions: 0%, 3% and 5% body mass added weight (AW) attached to the lower body. Moderately loaded WR (3% AW) resulted in higher horizontal force and horizontal power outputs compared to heavier loading during the acceleration phase. Sprint acceleration biomechanics were minimally affected by WR loading up to 5% AW
A FLOW VISUALEATION OF UNDULATORY UNDERWATER SWIMMING -A PILOT STUDY OF THREE DEIMENTIONAL AMALYSIS
Full text linkThe purpose of this study was to visualize the flow characteristic behind a swimmer during undulatory underwater swimming (UUS). A male college swimmer performed dolphin kicks in a water flume channel (flow velocity was set at 0.8 m+sl). By using the stereo PIV system, we captured the flow vector field in cross-sectional areas behind the swimmer and the swimmer\u27s motions with a synchronized motion capture system. The vector fields were averaged for each kicking phase, and for spatial cross-sectional plane. This enabled visualization oft he three dimensional flow field in UUS. The results showed that the swimmer created a counter vortex pair around the feet before the downward kid, and this appeared to assist the generation of thrust during the down kick motion
X-FACTORS IN STRAIGHT PUNCHES
No full textStraight punches are proven to be one of the most effective punches in Wing especially when boxers aim for far-reaching targets. Powerful straight punches require boxers to produce a series of force transfers from lower limbs to fists. Mechanically, the forces created from the lower limbs are approximately perpendicular to the forces created by fists. Hence, the forces from fists may not be derived from forms created from lower limbs as traditionally believed. This paper attempted to find the kinetic link of force transfer from lower limbs to fists. Three elite boxers were recruited in this study. Six high speed camera and two force platforms were used to collect data and 3D analysis was performed. The results showed that an X-factor contributed to the acceleration of straight punches resulted in the force of a straight punch
COURSE ANALYSIS OF APPROACH TECHNIQUES OF 3/4-CUT IN WATER SKI JUMP
Full text linkThe purposes of this study were to examine differences in how the Japanese elite jumper and the university level jumper executed the 3/4-cut jump technique and use of findings in improving instruction of water ski jumping. The distance obtained from a water ski jump depends heavily on the skier\u27s "approach speed" to the ramp. In maximizing speed to the ramp, jumpers can choose different techniques. In this study the speed and the angular displacement of jumpers using the 3/4-cut technique were calculated by digitizing ski motion. The results are summarized as fallows; 1 ) deceleration in speed during the Turn phase" was related to the angular displacement of the Japanese elite jumper and the university level jumper, and 2) the timing of the smallest angle at the "Final-cut phase" was different between the good jumps and the bad jumps
THE DISCRIMINATION OF BARBELL WEIGHT FOR WEIGHTLIFTERS
Full text linkTen 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
REACTIVE STRENGTH INDEX-MODIFIED IN DIFFERENT PLYOMETRIC TASKS
Full text linkThe Reactive Strength Index-Modified (RSl,d) is a reliable method of measuring the explosiveness of an athlete during a range of plyometric exercises. The purpose of the current study was to measure the between-limb differences in RSlmod across three different plyometric tasks. Eleven recreationally active participants performed countermovement jumps, stop jumps and single-leg jumps. The study found no significant differences in RSlmod between dominant and non-dominant limbs across all three tasks (p>0.05), but did find RSI,d to be higher in the stop jump than a countermovement jump and single leg stop jump for both dominant and non-dominant limbs. These findings show RSlmod may not be an indicator of limb asymmetry, but may be useful for the coach when looking to develop ex@losive performance in an athlete or performer
DECELERATION COUNTS: ESTIMATING THE ENERGY COST OF SHUlTLE RUNNING FROM MECHANICAL WORK
Full text linkTo estimate the energetic requirements of 5-m shuttle running based on kinematic data, we devised a modified version of existing models for the estimation of the energy cost of gait. In our approach, negative/eccentric work during deceleration phases was added to positive/concentric work in propulsive phases. Ten subjects performed two 5-rnin trials at 50% and 75% of their maximal aerobic speed. The metabolic cost estimated from 30 kinematics was compared to that measured by a portable metabolimeter. The estimation error was 1.2 J/kg/s (7.3%): results encourage to apply this method for the estimation of the workload in sports involving frequent turns and changes of direction
THE INFLUENCE OF SOLE LONGITUDINAL BENDING STIFFNESS ON PUSHOFF BIOMECHANICS IN FULL EFFORT LINEAR ACCELERATION
Full text linkThe purpose of this study was to identify the effect of longitudinal bending stiffness (LBS) alterations of running shoes in the initial push-off of the front leg in a linear acceleration task. 14 male sport students were analysed using a full body 3D motion analysis in combination with ground reaction force measurements during the initial step of a full effort 5 m sprint. lncreasing LBS did not lead to a significant increase of normalized average acceleration power, but affected MTP and ankle biomechanics. Push-off time was systematically increased with increased LBS. Average ankle joint moments were reduced, even though average GRF lever arms were increased with higher LBS. Increasing the power generation capacities of ankle plantar flexors combined with LBS increase might be a promising combination to improve acceleration performance
MUSCLE ACTIVITY DURING GAIT ON A TREADMILL: A COMPARISON BETWEEN ANTERIOR CRUCIATE LIGAMENTS (ACL) AND NORMAL SUBJECT\u27S
Full text linkThe aims of this research are to investigate and compare the muscles activity during gait on a treadmill for ACL subjects who underwent surgery and did not undergo surgery, and comparing them with normal subjects. The question that need to be solved is do the ACL subject who underwent or did not undergo surgery shows similar muscles force compared to normal subject? Walking activity of 12 subjects on a treadmill were captured using Vimn Nexus system and electrompgraphy (EMG) and analyzed. As a result, the comparison between ACL subjects shows that subject who underwent and did not undergo surgery used mainly soleus and gluteus maximus muscles, similar to normal subjects but the muscle forces produced were different. Besides, range of all ACL subjects\u27 muscles who went through surgery was found to be similar to normal subject\u27s
Acute effect of Kineslo Taping on Knee Joint Blornechanics during Drop Vertical Jump In Anterlor Cruclate ligament-Deflcient Knee
Full text linkKinesio tape (KT), an elastic therapeutic tape, is useful for prevention and treatment of sport injury, but their efficacies remain unclear on mechanical change. The purpose of this study was to analyze the acute effect of KT on knee joint biomechanics during drop vertical jump in individuals with ACL injuries. Seven participants with partial ACL tears performed drop vertical jump (DVJ) with and without ACL KT taping technique. Peak knee joint angles and moments, and knee joint angle at initial contact were obtained from 3D motion analysis system. Paired t-test did not reveal significant differences of knee joint biomechanics between the 2 conditions. In conclusion, KT did not produce any biomechanical change in participants with partial ACL tears