ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive
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OPTIMISING MECHANICAL POWER OUTPUT IN WEIGHTED BACK SQUATS - A JOINT LEVEL ANALYSIS
Get PDFWhen performing resistance training to improve muscular power output it is desirable to train with a resistance that maximises mechanical power. Previous studies investigating what resistance maximises power output show varied results and generally lack mechanistic conclusions. To address this we studied the whole-body and lower-limb joint mechanics of weighted back squatting. Ten male rowers performed maximal power squats with an Olympic bar and weights equivalent to 0, 10, 20, 40, 60 & 80% of their 1 RM. Whole-body power did not peak at a single resistance but over the range of 20-60%. This was owing to a trade-off in knee and hip powers that were maximised at 20% and 60%, respectively. When determining training resistances, practitioners should consider what joint powers should be emphasised in relation to the mechanics of the target sport
VALIDITY OF ESTIMATING ACTIVE DRAG USING THE BOTH ASSISTED AND RESISTED TECHNIQUES WITH FLUCTUATING VELOCITY
Get PDFThe main purpose of this study was to examine the validity of assisted and resisted techniques which are used for active drag estimation. Ten national and international male sprint swimmers performed two maximum effort free swims, two passive trials and two active drag trials in each technique. The computation of active drag for both techniques was based upon assumptions of the Velocity Perturbation Method (VPM) of Kolmogorov and Duplishcheva (1992). Results of a one-way ANOVA with repeated measures indicated there was no statistical significance between the active drag values obtained from the assisted and resisted techniques (p=0.05). There was however variation between active drag values. This is likely due to different power outputs that were applied during the test conditions and also, active drag varies as a function velocity squared
A BIOMECHANICAL STUDY ON IMPROVEMENT IN THE OVERARM THROWING TECHNIQUE OF ELEMENTARY SCHOOL CHILDREN
Get PDFThe purpose of this study was to investigate the improvement in technique of the overarm throwing due to a training with the standard motion model in elementary school children. Thirty-two children from the sixth grade were participated in three sessions: the pre- and post-training videotaping and throwing technique training sessions. Their throwing motions were videotaped with two high-speed cameras and analysed three-dimensionally. Through the training with the use of the standard motion model as a reference, the throwing distance and release parameters significantly improved. The throwing motion changed to be similar to the standard motion model after the training. The results indicated that the use of the standard motion model was useful for the improvement in the throwing techniques and throwing distance of less experienced children
A BIOMECHANICAL COMPARISON OF THE CROSSOVER STEP AND JAB STEP TECHNIQUES IN THE PUSHOFF OF BASE STEALING STARTS IN BASEBALL
Get PDFThe aim of this study was to compare the effectiveness of the crossover step (CS) and jab step (JS) start techniques in baseball base stealing. Fourteen varsity fielders participated in the study. An automatic motion capture system and synchronized force platforms were used to analyze the two start techniques, performed at full effort by each individual. No statistical difference was found in the start time (duration of the start phase) between the two techniques. However, the start velocity (forward velocity of the body CG at the end of right leg push-off phase) was significantly larger in JS than in CS. It was found that the difference in the start velocity between the two step techniques comes from the difference in the forward impulse generated by the left leg push-off
STRENGTH, BALANCE, AND FLEXIBILITY CHARACTERISTICS OF GOLFERS OF A VARIETY OF HANDICAPS
Get PDFThis research aimed to examine golf drive performance measures and physical performance variables of balance, strength and flexibility, for a wide range of golfing handicap levels. A total of 26 healthy right-handed golfers volunteered to participate in this study (M=17, F=9, 18-50 years, 0-36 handicap). Testing included an assessment of strength (hand grip strength test), balance (3 point star balance test), flexibility (sit and reach and shoulder reach flexibility), and indoor drive shot ball launch characteristics (high speed ball launch monitor). Golfers in the low handicap group had significantly (p?0.05) greater balance, strength, left shoulder flexibility, and better shot performnce than high handicap golfers. This research presents a rationale for the inclusion of strength, balance and flexibility conditioning in golf training programs
TEMPORAL, FORCE AND POSTURAL ANALYSIS OF RELEVÉ EN POINTE IN NOVICE AND INTERMEDIATE DANCERS
Get PDFThis study compares temporal, vertical force and postural sway variables between novice and intermediate dancers performing echappé relevé en pointe (a); to determine the influence of experience on intra-individual variability on the aforementioned performance parameters (b). Six trials performed by four novice and four intermediate dancers on a force platform were analysed. Large differences between the two groups of dancers were observed in the duration of the transition phase from the plié to the en pointe and in the length of sway path of the CoP during the en pointe phase. High loading rate was recorded when landing en pointe. Both groups of dancers showed a relatively large rate of intra-individual variability that can be seen as a task-relevant learning facilitator factor
STABILITY OF MEAN VALUES: APPLICATION OF THE BATES METHOD TO FIELD HOCKEY
Get PDFA limitation within biomechanics research is an insufficient number of trials are analysed. Conjecture exists over the minimum number of trials required to achieve a stable mean. This study was conducted to identify the minimum number of trials necessary for mean values of selected kinematic variables to stabilise, using the progressive standard deviation method adapted from Bates et al. (1983). Three-dimensional kinematic data of the field hockey hit was collected using a 10-camera Vicon motion analysis system and analysed using Visual 3D (C-Motion). Mean values for selected parameters were calculated and the progressive change in standard deviation assessed. Results showed the number of trials needed for mean stabilisation is both parameter and task specific. The last threshold approach should be used to account for variability within parameters
INVESTIGATION OF COACH RATINGS OF TECHNIQUE AND FORCE-TIME PROFILES IN ELITE MALE FRONT CRAWL SPRINT SWIMMERS
Get PDFThe purpose of this investigation was to examine the relationship between assisted towing method (ATM) force-time profiles and coach ratings of front crawl technique. Nine elite male swimmers completed the ATM sprint swimming protocol to obtain active drag and propulsion values. Six coaches each rated overall technique from video footage and technique at each of four stroke events (entry, pull, push, and exit) from images captured throughout the ATM trials. Mean coach technique rating scores were then correlated against four performance measures (FINA point score, 100 m performance best time, active drag value and propulsion value). Results demonstrated weak to strong relationships between the ratings and performance variables for each stroke event
STUDIES REGARDING THE DIFFERENCE BETWEEN NORMAL SPRINTING AND RUNNING OVER FLAT MARKERS
Get PDFThe purpose of this study was to clarify the difference between normal sprinting (NS) and running over flat markers (FMR). Eleven male collegiate sprinters participated in this study as subjects. The subjects initially ran 50m normally, then over some markers set up on the runway, and finally they ran 50m normally again. The leg motion of the three runs were compared by two-dimensional motion analysis. FMR showed a significant increase in stride frequency, but leg motion showed no significant differences. However, there were subjects whose leg motion showed smaller hip and knee angle and angular velocity during contact phase. The results suggested that the second sprint was influenced by FMR. FMR may be a good tool for sprinting improvement to obtain a higher stride frequency
AN EXPLORATION OF THE EFFECT OF KNEE-TO-FEET JUMPS ON PERFORMANCE
Get PDFThe purpose of this study was to test the effect of knee-to-feet jump training on power and vertical jump height. Twenty-one varsity athletes from power-emphasized sports were paired and randomly placed in the control or experimental group. All subjects completed pre- and post-tests of vertical jump height, knee-to-feet jump height, and 2 repetition maximum hang clean. The experimental group completed a 6 week program of knee-tofeet jumps. There was no significant difference in vertical jump height or hang clean weight from pre- to post-test; however, the experimental group significantly improved in knee-to-feet jump height. There was a positive correlation between knee-to-feet jump and vertical jump height indicating knee-to-feet jumps are a potentially useful tool worth further pursuit