Visual guidance during competition performance and run-through training in long jumping

To ensure precise foot placement on the take-off board, long jumpers visually regulate their stride pattern during their run-up. A relationship between how much visual guidance they use and the horizontal distance they jump has not, however, been quantified. Run-up precision is often practiced using run-throughs, which exclude the take-off and, therefore, the high physical stress of the complete long jump. The validity with which this common training method simulates the long jump approach remains, however, to be verified. Four state-standard long jumpers and two heptathletes completed two sessions, each comprising six run-throughs and six competition long jumps. A 50 Hz video camera was manually panned from an elevated platform to film each trial, to enable subsequent gait characteristic evaluations. Linear regression analyses identified that a longer visual regulation phase, measured in time, distance or number of strides, was a key predictor of long jump distance. The number of strides that were visually regulated during the long jump approach was, accordingly, positively correlated with long jump distance (r = 0.67, p = 0.001). The amount of visual regulation used during run-throughs was, however, less than half (p = 0.001) of that observed during long jump approaches. Our results should compel long jump coaches to supplement run-through training with additional visual guidance exercises, to encourage their athletes to visually regulate more of their long jump approach.<br /

Validity and reliability of accelerometry for assessing impact loads in jumping tasks

High injury rates in gymnastics have been suggested to be related to impact loading. This study examined the validity and reliability of a tri-axial accelerometer, mounted on the upper back, to estimate impact loads. Twelve female participants performed a continuous double legged hopping task and rebound jumps from a drop of 40, 60 and 80 cm. Peak resultant acceleration (PRA) showed moderate to good reliability. Correlation coefficients between ground reaction force (GRF) and PRA ranged from rs=0.860 for the continuous hopping task to rs= 0.608 for rebound jumps from 80 cm, and were all significant. The results of the current study support the use of PRA to estimate impact load in jumping tasks, and show potential for this measure to be employed in a gymnastics training setting

VISUAL REGULATION DURING COMPETITION LONG JUMPS AND RUN-THROUGHS

Previous investigators have reported that the ability of long jumpers to visually regulate their stride pattern as they approach the take-off board is critical for success. The importance of visual regulation (VA) on long jump (LJ) distance was assessed in six national-class competitors during two simulated competitions. Linear regression analyses indicated that increased VR contributes to a high average approach velocity -a key predictor of LJ distance. Early VA enabled the athletes to make small systematic adjustments to stride length in order to strike the board in an optimal take-off position, without sacrificing approach velocity. Athletes practice their LJ approach by repeating the stride pattern of the approach, but without the take-off. The current study established that these 'run-throughs' (AT) don't accurately simulate the VR characteristics of a LJ approach. One strategy to increase the VA required during RT's may be to place additional targets across the runway for the athletes to negotiate whilst approaching the take-off board, without compromising approach velocity

VALIDITY AND RELIABILITY OF ACCELEROMETRY FOR ASSESSING IMPACT LOADS IN JUMPING TASKS

High injury rates in gymnastics have been suggested to be related to impact loading. This study examined the validity and reliability of a tri-axial accelerometer, mounted on the upper back, to estimate impact loads. Twelve female participants performed a continuous double legged hopping task and rebound jumps from a drop of 40, 60 and 80 cm. Peak resultant acceleration (PRA) showed moderate to good reliability. Correlation coefficients between ground reaction force (GRF) and PRA ranged from rs=0.860 for the continuous hopping task to rs= 0.608 for rebound jumps from 80 cm, and were all significant. The results of the current study support the use of PRA to estimate impact load in jumping tasks, and show potential for this measure to be employed in a gymnastics training setting

LITTLE GIRLS TO ADVANCED GYMNASTS: WHAT CAN WE LEARN FROM THE SURVIVING GYMNASTS?

TTalent identification programmes are widely employed in gymnastics to select young girls whom are thought to exhibit the pre-requisite traits to excel at the elite level in the future. This study revisits the Thomas, Wilson, and Bradshaw (2013) paper on 5-8 year old talent selected artistic gymnasts. The Gymnastics Victoria and Gymnastics Australia websites were data mined to track the competition history of these gymnasts. The original data (e.g. anthropometry, jump biomechanics) of the gymnasts that survived to an advanced level were compared against those whom did not, using the Kruskal Wallis test. The analysis revealed that better drop jump performance was the key indicator of longer term talent potential. Prospective analysis on surviving gymnasts provides better insights on the key attributes related to future advanced gymnastics potential

IDENTIFICATION OF FLOOR AND VAULTING APTITUDE IN 8·14 YEAR OLD TALENT-SELECTED FEMALE GYMNASTS

Training programs can be designed and monitored to maximise high aptitude for floor and vault when the key attributes are identified, and then used to recognize apparatus ability in talent-selected gymnasts. The aim of this study was to identify the anthropometric and physical prerequisites for high difficulty floor tumbling and vaulting. Twenty female gymnasts performed handstand push-offs, single and multiple jumps on a portable Kistler force plate. The gymnasts were also examined when sprinting, vaulting, and performing broad jumps. Each gymnast's best vault, three best noor tumbling skills and their anthropometric characteristics were also recorded. High squat jump force and power, vault take-off velocity, and sprinting speed indicated vaulting talent. High vault running speed and reduced handstand push-off ground contact time indicated high floor ability

OPTIMAL CRANK ARM LENGTH AND BODY POSITION FOR ROAD SPRINT CYCLING PERFORMANCE

The purpose of the current study was to examine the effects of body position and crank arm length (CAL) on power production in road sprint cycling. Six well trained male cyclists were tested in the standing and seated positions, and with three CALs of 18, 20 and 22 % of leg length whilst out of the saddle. A modified six second Wingate test on a Velotron ergometer was used to measure power (Watts) and cadence (rpm), and a Vicon MX system was used to measure the hip and lower limb kinematics of the pedal cycle. A 4% increase in power was observed when riding out of the saddle and a CAL set at 18- 20% of leg length was superior for this task. The coordination pattern employed was consistent between postures and with different CALs

Information-based regulation of high-velocity foot-targeting tasks

Judging time-to-contact with a target is an important criterion for avoiding harm in everyday walking and running tasks, and maximizing performance in high-velocity sporting tasks. The information-based regulation of step length and duration during target-directed locomotion was examined in relation to gait mode, approach velocity, target task, expertise, and sporting performance during a series of four experiments. The first three experiments examined novice performers (Each n=12, 6 males, 6 females), whilst the last experiment examined expert gymnasts (n=5). Two reference strips with alternating 50cm black and white intervals were placed on either side of the approach strip for all of the experiments. One 50Hz-panning video camera filmed the approach from an elevated position. In Experiment 4, two stationary 250Hz cameras filmed the post-flight performance of the gymnastic vaults and, in addition, two qualified judges provided a performance score for each vaulting trial. The panning video footage in each experiment was digitized to deduce the gait characteristics. In Experiment 4, the high-speed video footage was analyzed three-dimensionally to obtain the performance measures such as post-flight height. The utilization of visual stimulus in target-directed locomotion is affected by the observer\u27s state of motion as characterized by the mode of locomotion and also often the speed of locomotion. In addition, experience plays an important role in the capacity of the observer to utilize visual stimulus to control the muscular action of locomotion when either maintaining or adjusting the step mechanics. The characteristics of the terrain and the target also affect the observer\u27s movement. Visual regulation of step length decreases at higher approach speeds in novice performers, where as expert performers are capable of increasing visual regulation at higher approach speeds. Conservatism in final foot placement by female participants accounts for the observed increase in distance from the critical boundary of the obstacle relative to toe placement. Behavioural effects of gender thus affect the control of final foot placement in obstacle-directed locomotion. The visual control of braking in target-directed locomotion is described by a tau-dot of-0.54. When tau-dot is below -0.54 a hard collision with the obstacle will occur, however, when tau-dot is above -0.54, a soft collision with the target will occur. It is suggested that the tau-dot margin defining the control of braking reveals the braking capacity of the system. In the target-directed locomotion examined a tau-dot greater than -0.70 would possibly exceed the braking capacity of the system, thus, leading to injury if performed. The approach towards the take-off board and vaulting horse in gymnastics is an example of target-directed locomotion in sport. Increased visual regulation of the timing and length of each step is a requirement for a fast running approach, a fundamental building block for the execution of complex vaults in gymnastics. The successful performance of complex vaults in gymnastics leads towards a higher judge\u27s score. Future research suggestions include an investigation of visual regulation of step length in curved target-directed locomotion

IS JUMPING AND LANDING TECHNIQUE SYMMETRICAL IN FEMALE GYMNASTS?

The effect of eccentric load (drop height) on lower extremity neuromuscular function and performance was examined in young healthy female gymnasts. Each gymnast (level 4 – 6, n = 15) performed five drop landings and five rebound jumps whilst barefoot from three heights (30, 60, 90 cm) onto two AMTI force platforms (1000 Hz) covered with 6 cm thick carpeted gymnastics mats. Force-time measurements were exported into custom-written software to obtain key measures such as peak force (BW), loading rate (BW/s), and takeoff power (Watts/kg). Significant asymmetry was identified in the jumping and landing performance of the gymnasts, however the level of asymmetry observed was not influenced by eccentric load. In conclusion, coaches should aim to achieve safer landing strategies by developing ambidextrous movement in young gymnasts

LATERALITY AND ITS EFFECT ON LOWER EXTREMITY MUSCULOSKELETAL STIFFNESS IN MALE SOCCER PLAYERS AND TRACK RUNNERS

The purpose of this study was to determine the influence of laterality on lower extremity stiffness in healthy soccer players and track runners. Eight soccer players aged 15 to 17 years, and eight track runners, aged from 18 to 25 years performed a battery of tests (Single and double legged continuous straight and bent-legged jumping, and running) to determine lower extremity musculoskeletal stiffness. All participants were injury free at the time of testing. Statistical tests of the various all kinetic measures revealed that the track runners were asymmetrical in their musculoskeletal performance qualities, whereas, the soccer players displayed symmetry. Future research should examine lower extremity symmetry in an older group of soccer players, and the development of a training program to alter lower extremity stiffness into a typical range