TECHNICAL CHANGES IN HURDLE CLEARANCES AT THE BEGINNING OF 110 M HURDLE EVENT - A PILOT STUDY

Practically in all hurdle studies, the analysis has been carried out over a single hurdle. The purpose of this study was to investigate individual differences in hurdle clearances at the first 4 hurdles. Two male athletes were videotaped and 3D analysis was carried out. Athlete A showed a more consistent pattern than athlete B in over a range of variables. Athlete A was also able to increase the mean horizontal velocity from hurdle to hurdle. From a coaching point of view the main issues for athlete A are to avoid drifting too close to the first hurdle and to try to take-off more aggressively forward. Subject A's lead leg worked very well before and after the hurdle. Subject B has most problems around the lead leg, i.e. it is not bent enough at the take-off and it is not working effectively at the landing contact

A NEW METHOD FOR EVALUATING THE BALANCE BETWEEN THE DIFFERENT PHASES IN 100 M SPRINTING

The aim of this paper was to investigate, whether it is possible to objectively evaluate the relationship between three different phases of 100 m sprint running. Following correlation analyses from six major athletics championships, a linear regression based scoring system was created for the acceleration, maximum velocity and velocity maintenance phases. The scoring system can be used for athletes from international level down to moderate national level. Tests for two female juniors showed that the maximum velocity phase was the weakest part of their performance. Therefore, recommendations can be made to coaches for changes to be made in training. This strategy has already resulted in improved balance between different phases for a specific athlete. Current studies are expanding the analysis into the area of individual running gait variables

FORCE PRODUCTION IN THE FIRST FOUR STEPS OF SPRINT RUNNING

The purpose of this investigation was to understand how the athlete produces acceleration during the first steps of sprint running. One athlete performed four starts from starting blocks over a series of four force plates. Horizontal impulse (which directly relates to the acceleration of the athlete) gradually decreased after leaving the blocks, while this decrease was transferred to a gradual increase in vertical force production to support the small but required vertical movement of CM in order to increase flight time (to gain longer steps). It also seems that the body can compensate for some technical mistakes during the performance, as the results revealed that an extended braking time in one step yielded a reduced braking time in the next step. This implied that the increased time in the contact was used to get other body parts into more favourable positions for the next step

THE EFFECT OF THE BEND ON TECHNIQUE AND PERFORMANCE DURING MAXIMAL SPEED SPRINTING

For 200 and 400 m races half of the race is run around the bend. This study aimed to understand the changes in kinematics that occur during maximal effort bend sprinting. Velocity reduction (5%) on the bend compared to the straight was, for the left step, mainly due to increased (20%) touchdown distance and some angular kinematics changes which led to increased contact time and reduced step frequency. During the right step, performance dropped mainly due to a reduction in step length. It is likely that changes caused by inward lean, to counteract moments caused by centripetal forces, on the bend contributed to detrimental changes in sagittal plane kinematics (e.g. knee flexion at touchdown) normally associated with superior performance in sprinting. Similar to straight sprinting, reduced touchdown distance could hold the key to improve bend performance

BEND SPRINTING AT DIFFERENT RADII OF AN OUTDOOR ATHLETICS TRACK

Athletes in the inners lanes may be at a disadvantage during sprint races that contain a bend portion. This study investigated the effect on performance when sprinting on the different radii of an outdoor track. There was an approximately 2% reduction in mean race velocity from lane 8 (left step: 9.56 m/s, right step: 9.49 m/s) to lane 5 (left step: 9.36 m/s, right step: 9.30 m/s), with only slight further reductions from lane 5 to lane 2 (left step: 9.34 m/s, right step: 9.30 m/s). This was mainly due to reductions in step frequency as radius decreased. The disadvantage of the inner lane compared to the outer lane may be greater than previously suspected. Larger race velocity standard deviations as radius decreased may be indicative of athletes being differently able to accommodate running at tighter radii than others. This may have implications for training and competition

UNDERSTANDING ELITE SPRINT START PERFORMANCE THROUGH AN ANALYSIS OF JOINT KINEMATICS

This study aimed to investigate how leg kinematics contribute to the performance, in terms of external horizontal power production, of three elite sprinters during the block and first step phases of a sprint. The highest block phase power was produced by sprinter B, who exhibited the greatest hip extension, particularly at the rear leg. Sprinter A achieved a higher horizontal block exit velocity, however, this appeared to be due to a longer push duration rather than greater average force production. The highest horizontal power during the first stance was again produced by sprinter B, who exhibited the greatest total stance leg joint extension. The other two sprinters exhibited similar leg extension to each other. However, sprinter A was able to generate greater horizontal power, which may have been due to his centre of mass being further in front of his foot at touchdown

SHOULD ATHLETES USE THEIR STRONGER LEG ON THE FRONT BLOCK DURING THE SPRINT START?

The aim of this study was to understand force production differences Men alternating feet on the starting blocks. The hypothesis was that the dynamically stronger leg should be on the front. Utilising force plates, eight male athletes performed starts alternating the front foot on the block, as well as single leg vertical countermovement jumps to test dynamic strength. In total, 121 starts were analysed. At the group level, there were no statistically significant differences in any of the force variables between dynamically stronger and weaker leg. The results raised some doubts to the theory that the stronger leg should be on the front block during the sprint start. Consequently, the advice for coaches training developing athletes is to allow athletes to use the block settings they feel comfortable with, rather than trying to overanalyse which leg should be on the front or rear block

A LONGITUDINAL CASE STUDY OF STEP CHARACTERISTICS IN A WORLD CLASS SPRINT ATHLETE

The relative importance of step length (SL) and step frequency (SF) to maximum velocity sprinting is not yet fully understood. One elite male sprinter was studied during five months of training. Step velocity, SL and SF were calculated from 50 Hz video, using manual digitization and 2D DLT, for a total of 113 steps taken from the maximum velocity phase of training sprints. Mean values were calculated for each session and tracked against training diary information gathered from the athlete's coach. Chronological information showed that as the athlete’s training progressed, a link between velocity and SF was maintained whilst mean session SL remained relatively unchanged throughout. For the athlete studied, changes in step velocity as a result of training were shown to occur as a consequence of changes mainly in SF

Use of Statistical Parametric Mapping to Reveal Novel Athlete-Specific Kinetic Determinants of Sprint Start Performance

The powerful development of force largely determines sprint start performance. However, to date, block phase kinetics have only been examined using discrete (0D) variables. One male sprinter completed 16 sprint starts whilst the ground reaction forces applied by each limb were measured. Kinetic predictors of horizontal external power were identified using Pearson r for 0D variables and statistical parametric mapping (SPM) to assess entire force curves. Pearson’s correlations revealed fast horizontal force production to result in better performance, but maximum forces appeared important only for the rear leg. Conversely, SPM results suggested that horizontal forces in the early push phase (initial 15-30%) were important for both legs. Testing entire force curves using SPM can supplement 0D analysis to identify kinetic factors which would otherwise be undetected

KINETIC FACTORS DIFFERENTIATING MID-TO-LATE SPRINT ACCELERATION PERFORMANCE IN SPRINTERS AND SOCCER PLAYERS

High-speed running in soccer is an important skill, however, the underlying kinetic factors are not fully understood. Ground reaction forces from steps 8 to 24 of maximal-effort sprints were captured for 24 soccer players and 28 track and field athletes using 54 force plates. Correlations between discrete force variables and horizontal acceleration were assessed, and statistical parametric mapping revealed performance associations across entire waveforms. Track and field athletes produced higher forces (mean anteroposterior: 1.56 N·kg-1) across shorter contacts (0.101 s) than soccer players (1.27 N·kg-1, 0.110 s). Interestingly, the technical ability to apply force and the performance-differentiating parts of stance were similar across groups. Thus, practitioners should perhaps target physical (force production) rather than technical factors to improve soccer players’ sprint abilities