Sprint Hurdles SPRINT HURDLE RACES: A KINEMATIC ANALYSIS

Transcription

1 Sprint Hurdles SPRINT HURDLE RACES: A KINEMATIC ANALYSIS By Pierre-Jean Vazel, December 2011 In order to prescribe the most effective training possible it is important for coaches to have a sound understanding of the events they are targeting. This article uses historical data collected for the sprint hurdle events in order to establish their unique properties and highlights some key issues this data raises for coaches. Data Collection Methods High hurdles races are defined as sprinting over 110m (for men) and 100m (for women) with 10 barriers. Specifications as ruled by IAAF are shown in Table 1. Gender Overall distance Distance 1 st hurdle Interval distance 10 th hurdle to finish MEN 110 m 13,72 m 9,14 m 14,02 m WOMEN 100 m 13,00 m 8,50 m 10,50 m Table 1: Race specifications for the sprint hurdle races In order to compare the structure of the race profiles both by the same individual on different occasions and between athletes, for decades coaches and researchers alike have been collecting data on the times taken to reach each hurdle. Traditionally there are two common methods for collecting this data. In the first method, the individual times are taken as the athlete crosses the hurdle, while in the second method, the times are taken at the touch-down of the lead foot after each hurdle. It should be noted that these touch down times are dependant on the distance from the hurdle to the landing of the lead foot, which may vary significantly with the athlete s technique. Hence times taken from the start to the first hurdle and from the last hurdle to the finish line should only be considered when comparing an individual against themselves. Practical coaching application When taking split times in practice, remember that there will be a large variation in the time from the start to first hurdle and from the last hurdle to the finish depending on how close to the barrier the athlete lands. Therefore, the most accurate touchdown times will be those between the hurdles. Hence, it is best to use touchdown times between barriers to assess an athlete s progress during practical coaching sessions. If times from the start to the first barrier or from the last barrier to the finish are to be considered, they should only be used to track an athlete s progress relative to themselves and not their competitors. Page 1 of 10

2 Exclusively using the second method (touchdown after each hurdle), the most widely used and most accurate one, this paper summarises past research and updates it with unpublished analysis based on a unique database of quality sprint hurdle performances. Velocity Profiles of the Short Hurdle Events Touch-down times and interval times for World Record (12,87s) holder Dayron Robles are shown on Table 2. For the sake of comparison, a database of 100 male performers was divided in two groups. Group 1 (G1) comprises performers in the s range and is compared with Group 2 (G2) made up of athletes in the s range. Data from women s 100m hurdles is shown in Table 3. The 85 performers are divided in two groups: G1 includes performers in the s range, while G2 includes s performers. Yordanka Donkova s World Record (12.21) analysis was not available, hence the 2011 World Leading mark, 12.28s by Sally Pearson, the best time in 19 years, was chosen. In order to put these actual performances into perspective, the fastest units ever recorded are also included. MEN 110MH RT 1H 2H 3H 4H 5H 6H 7H 8H 9H 10H 110 D.Robles WR 0,14 2,47 3,48 4,46 5,46 6,44 7,43 8,43 9,44 10,46 11,49 12,87 (12,87 s) 1,01 0,98 1,00 0,98 0,99 1,00 1,01 1,02 1,03 1,38 G 1 (n=49) 0,15 2,57 3,62 4,63 5,63 6,63 7,64 8,66 9,68 10,72 11,77 13,15 (12,87-13,49s) 1,05 1,01 1,00 1,01 1,01 1,02 1,03 1,04 1,05 1,38 G 2 (n=51) 0,15 2,62 3,68 4,72 5,76 6,79 7,83 8,88 9,94 11,02 12,11 13,54 (13,50-13,70s) 1,06 1,04 1,04 1,03 1,04 1,05 1,06 1,08 1,09 1,43 Fastest units ever recorded 2,46 0,99 0,98 0,97 0,97 0,97 0,97 0,99 0,99 1,01 1,30 Table 2: Touch-down intervals for high-level male hurdlers Page 2 of 10

3 Robles (12,87 s) G1 (13,15 s) G2 (13,54 s) Graph 1: Velocity curve for different groups of male hurdlers WOMEN 100MH RT 1H 2H 3H 4H 5H 6H 7H 8H 9H 10H 100 S.Pearson WL 0,145 2,485 3,475 4,445 5,400 6,350 7,290 8,25 9,220 10,195 11,195 12,275 (12,28 s) 0,990 0,970 0,955 0,950 0,940 0,960 0,970 0,975 1,000 1,080 G 1 (n=42) 0,16 2,55 3,56 4,55 5,52 6,48 7,44 8,41 9,39 10,38 11,39 12,49 (12,25-12,65 s) 1,01 0,99 0,97 0,96 0,96 0,97 0,98 0,99 1,01 1,10 G 2 (n=43) 0,16 2,59 3,63 4,64 5,64 6,63 7,62 8,62 9,63 10,66 11,70 12,83 (12,66-12,99 s) 1,04 1,01 1,00 0,99 0,99 1,00 1,01 1,03 1,04 1,13 Fastest units ever recorded 2,47 0,98 0,95 0,94 0,94 0,93 0,94 0,94 0,96 0,98 0,98 Table 3: Touch-down intervals for high-level female hurdlers Page 3 of 10

4 Pearson (12,28 s) G1 (12,49 s) G2 (12,83 s) Graph 2: Velocity curve for different groups of female hurdlers When we look at the velocity profiles that can be created from the touchdown data for the short sprint events, it is remarkable that in both men and women, the speed difference between the groups is opened in the first 30m of the race, or up to the 3rd hurdle. Both groups also reach their top speed in similar places, at around 50m, and afterwards the curves remain parallel. In other words, the speed maintenance (ratio at which speed is lost) is the same for all groups of performance. Practical coaching application The above data points to the importance of speed and power characteristics as the differentiating factor between good and great hurdlers. Great hurdlers do not slow down less than good hurdlers but instead simply execute each section of the race in a more explosive manner. What phases of the race correlate most with overall performance? When we look at which parts of the race correlate best with overall performance we find that the fastest interval units (highlighted in BOLD in the table) have the most importance regarding the final results of women s 100m hurdles, from the correlation analysis (table 3). However, in men s 110m hurdles, the highest correlations are found later in the race, suggesting that specific endurance is the key to achieve the best results. Page 4 of 10

5 MEN M HURDLES 0,15 0,63 0,60 0,79 0,82 0,82 0,85 0,87 0,88 0,85 0,77 0,60 RT S-1H 1-2H 2-3H 3-4H 4-5H 5-6H 6-7H 7-8H 8-9H 9-10H 10H-F -0,03 0,61 0,70 0,79 0,80 0,80 0,83 0,82 0,77 0,76 0,67 0,52 WOMEN M HURDLES Table 3: Dependence of interval times on the 110m hurdles (n=100) and 100m hurdles (n=85) results (correlation coefficients) Practical coaching application The above data points to slight differences in the characteristics of short hurdle events for men and women. For women, the lower hurdle heights create an event where the athlete that can accelerate most rapidly and achieve the highest top speed at around hurdle 6-7 is most likely to win the race. In the men s event the higher barriers create an additional challenge. Not only will the best athletes accelerate faster than their peers but they will also have the capacity to maintain the required power output for longer, typically through to hurdle 7-8, where their less powerful rivals drop away. So for men competing over the adult specification hurdles there is a greater specific endurance element to the race. Hurdle clearance and running between the barriers In order to determine the respective importance of clearance time (flight) over the hurdles and sprinting time (run-in) between the barriers, comparisons were made between different groups of performers. The first group of men (G1) includes 16 performers in the s range, and the second group comprised 49 performers in the s range. For the women the first group (G1) was made up from 16 performers in the s range and group two (G2) from 56 performers in the s range. Page 5 of 10

6 MEN 110MH PERFORMANCE START-TO 1H TOTAL FLIGHT TOTAL RUN-IN TD 10H-FINISH D.Robles 12,87 2,15 3,16 6,18 1,38 L.Xiang 12,88 2,20 3,52 5,83 1,33 D.Oliver 12,89 2,23 2,99 6,28 1,39 G1 (n=16) 12,96 (12,87-13,05) 2,21 (2,15-2,28) 3,28 (2,99-3,73) 6,11 (5,66-6,47) 1,36 (1,31-1,41) G2 (n=49) 13,86 (13,18-14,40) 2,29 3,66 6,47 1,45 WOMEN 100MH PERFORMANCE START-TO 1H TOTAL FLIGHT TOTAL RUN TD 10H-FINISH L.Narozhilenko 12,28 2,25 3,03 5,98 1,02 S.Pearson 12,28 2,18 2,95 6,07 1,08 Y.Donkova 12,29 2,19 2,72 6,26 1,12 G1 (n=16) 12,40 (12,28-12,48) 2,23 (2,18-2,28) 2,94 (2,72-3,26) 6,13 (5,82-6,36) 1,09 (1,02-1,13) G2 (n=56) 13,00 (12,58-13,60) 2,29 3,13 6,42 1,16 Table 4: Comparison of performance rhythmic structure for different groups of hurdlers. The data collected for the best ever hurdlers (G1) show huge differences between athletes in terms of their race structure. However, it is beyond the scope of this paper to determine exactly why this is, thought it probably has something to do with the influence of anthropometrics (body dimensions) and motor abilities (skills, speed, strength, endurance and flexibility). Most interestingly when it comes to some parameters, several of the best ever hurdlers exhibit some values more typically found in lower level athletes (G2), especially in relation to hurdle clearance times (total flight). However, when it comes to the three parameters related to the running part of the race (time from the start to the take-off before the 1st hurdle, total sprinting time during the intervals between hurdles and time from foot touch down after the 10th hurdle to the finish line) top performers generally outperform lower-level performers. The impact of the running part of the race over the hurdling part in terms of its influence on performance is clearly demonstrated by the correlation coefficients (that indicate how strongly a parameter correlates with overall race performance) shown in Table 5. MEN M HURDLES 0,17-0,12 0,40 0,11 Start-TO 1H Total Flight Total run-in TD 10H-Finish 0,60-0,04 0,27 0,48 WOMEN M HURDLES Table 5: Dependence of rhythmic structure parameters on the 110m hurdles (n=16) and 100m hurdles (n=16) results (correlation coefficients). Table 6 clearly shows that the step length during hurdle clearance and run-interval length between the barriers are the same for both elite and sub-elite hurdlers. As observed previously, hurdle clearance time - and thus its speed of execution - is important, but not as much as the time spent running between the barriers (run-interval time). Since the different level-groups have to cover the same distance is less time using three steps between each hurdle, the step frequency is the main parameter to improve in order to achieve a better final result. Page 6 of 10

7 HURDLE CLEARANCE RUN-INTERVAL Length (m) Time (s) Length (m) Time (s) Step Frequency MEN elite level 3,65 0,328 5,49 0,611 4,91 MEN sub-elite level 3,65 0,366 5,49 0,647 4,64 WOMEN elite level 3,20 0,294 5,30 0,613 4,89 WOMEN sub-elite level 3,20 0,313 5,30 0,642 4,67 Table 6: Comparison of parameters for hurdle clearance mean length and time, and run-interval mean length, time and step frequency between different group of elite male and female performers. Practical coaching application The data presented in the past section suggests that there is not one best way to execute the sprint hurdle races. This is indicated by the fact that many of the very best hurdlers of all time have used very different strategies to achieve similar performances. For example some spend a long time clearing the hurdle but make up for it by being extremely fast between the barriers. The reasons for this are probably related to both the physical characteristics of the athletes (height, limb lengths etc) as well as their technique. However, in general the athletes that are best at running between the barriers are most successful and hence a high step frequency is what differentiates elite hurdlers from their sub elite counterparts. In general step frequency for hurdlers will be determined both by technique and their elastic qualities, which allow them to minimise ground contact time in a similar way to high level sprinters. The velocity profiles of male and female races show a similar structure. The main difference lies in the hurdle clearance time, which is clearly shorter in women s 100m hurdle races, due to lower barriers (see Table 6). The women s hurdle height was raised after 1968 from 0.76 to 0.84 cm when the race was lengthen from 80m to 100m. Yet, this height is still proportionally lower than men s hurdles. This proportionally lower women s hurdle height leads to less deviation from the normal sprint stride and therefore favours speed based female hurdlers. This is clearly indicated by the statistics in Table 5 that shows sprinting speed into the first hurdle and from the last hurdle to the finish is highly correlated to the overall race results for women. This is not the case in the men s race where step frequency between hurdles is the most correlated with final performance. Modelling the sprint hurdle races Tables 7 and 8 present realistic models of the touch-down times during men s 110m hurdles and women s 100m hurdle races, based on the data recorded for 100 male and 85 female performers. An approximation for indoor 60m hurdles results has also been added by comparing the fifth hurdle touch-down times during 60m hurdles races with those from 110/100m hurdles races. Page 7 of 10

8 Practical coaching application Coaches can use the data in tables 7 and 8 to predict the kind of times their athletes should be capable of in competition from practice performances. Coaches can also use this data to see if their athletes are able to achieve a mature velocity curve or if they are lacking in specific endurance, maximum velocity or acceleration for example. Always remember that the time from the start to the first hurdle and from the last hurdle to the finish is dependant upon the landing distance from the barrier to the lead foot and so may vary somewhat from performance to performance and also between athletes depending upon technique and limb lengths etc. Page 8 of 10

9 1H 2H 3H 4H 5H 6H 7H 8H 9H 10H 110MH 60MH 2,51 3,53 4,51 5,48 6,44 7,41 8,39 9,37 10,36 11,37 12,70 7,29 1,01 0,98 0,97 0,97 0,97 0,97 0,98 0,99 1,01 1,33 2,52 3,53 4,52 5,50 6,47 7,44 8,42 9,40 10,40 11,42 12,75 7,32 1,02 0,98 0,98 0,97 0,97 0,98 0,98 1,00 1,02 1,33 2,52 3,54 4,53 5,51 6,49 7,46 8,45 9,44 10,44 11,46 12,80 7,34 1,02 0,99 0,98 0,97 0,98 0,98 0,99 1,00 1,02 1,34 2,53 3,55 4,55 5,53 6,51 7,49 8,48 9,47 10,48 11,50 12,85 7,36 1,02 0,99 0,98 0,98 0,98 0,99 0,99 1,01 1,03 1,35 2,54 3,56 4,56 5,54 6,53 7,51 8,51 9,51 10,52 11,55 12,90 7,38 1,03 1,00 0,99 0,98 0,99 0,99 1,00 1,01 1,03 1,35 2,54 3,57 4,57 5,56 6,55 7,54 8,54 9,54 10,56 11,59 12,95 7,41 1,03 1,00 0,99 0,99 0,99 1,00 1,00 1,02 1,04 1,36 2,55 3,58 4,58 5,58 6,57 7,56 8,57 9,58 10,60 11,64 13,00 7,43 1,03 1,00 0,99 0,99 1,00 1,00 1,01 1,02 1,04 1,36 2,56 3,59 4,60 5,59 6,59 7,59 8,60 9,61 10,64 11,68 13,05 7,45 1,03 1,01 1,00 0,99 1,00 1,01 1,01 1,03 1,04 1,37 2,56 3,60 4,61 5,61 6,61 7,62 8,63 9,64 10,68 11,73 13,10 7,48 1,04 1,01 1,00 1,00 1,01 1,01 1,02 1,03 1,05 1,37 2,57 3,61 4,62 5,63 6,63 7,64 8,66 9,68 10,71 11,77 13,15 7,50 1,04 1,01 1,01 1,00 1,01 1,02 1,02 1,04 1,05 1,38 2,58 3,62 4,63 5,64 6,65 7,67 8,69 9,71 10,75 11,81 13,20 7,52 1,04 1,02 1,01 1,01 1,01 1,02 1,03 1,04 1,06 1,39 2,58 3,63 4,65 5,66 6,67 7,69 8,71 9,75 10,79 11,86 13,25 7,54 1,05 1,02 1,01 1,01 1,02 1,02 1,03 1,05 1,06 1,39 2,59 3,64 4,66 5,68 6,69 7,72 8,74 9,78 10,83 11,90 13,30 7,57 1,05 1,02 1,02 1,02 1,02 1,03 1,04 1,05 1,07 1,40 2,59 3,65 4,67 5,69 6,71 7,74 8,77 9,82 10,87 11,95 13,35 7,59 1,05 1,03 1,02 1,02 1,03 1,03 1,04 1,06 1,07 1,40 2,60 3,66 4,69 5,71 6,73 7,77 8,80 9,85 10,91 11,99 13,40 7,61 1,05 1,03 1,02 1,02 1,03 1,04 1,05 1,06 1,08 1,41 2,61 3,66 4,70 5,73 6,75 7,79 8,83 9,89 10,95 12,03 13,45 7,63 1,06 1,03 1,03 1,03 1,04 1,04 1,05 1,06 1,08 1,42 2,61 3,67 4,71 5,74 6,78 7,82 8,86 9,92 10,99 12,08 13,50 7,66 1,06 1,04 1,03 1,03 1,04 1,05 1,06 1,07 1,09 1,42 2,62 3,68 4,72 5,76 6,80 7,84 8,89 9,95 11,03 12,12 13,55 7,68 1,06 1,04 1,04 1,04 1,05 1,05 1,06 1,07 1,09 1,43 2,63 3,69 4,74 5,78 6,82 7,87 8,92 9,99 11,07 12,17 13,60 7,70 1,07 1,04 1,04 1,04 1,05 1,06 1,07 1,08 1,10 1,43 2,63 3,70 4,75 5,79 6,84 7,89 8,95 10,02 11,11 12,21 13,65 7,73 1,07 1,05 1,04 1,04 1,05 1,06 1,07 1,08 1,10 1,44 2,64 3,71 4,76 5,81 6,86 7,92 8,98 10,06 11,15 12,25 13,70 7,75 1,07 1,05 1,05 1,05 1,06 1,06 1,08 1,09 1,11 1,45 2,65 3,72 4,78 5,83 6,88 7,94 9,01 10,09 11,19 12,30 13,75 7,77 1,07 1,06 1,05 1,05 1,06 1,07 1,08 1,09 1,11 1,45 2,65 3,73 4,79 5,84 6,90 7,97 9,04 10,13 11,23 12,34 13,80 7,79 1,08 1,06 1,06 1,06 1,07 1,07 1,09 1,10 1,12 1,46 2,66 3,74 4,80 5,86 6,92 7,99 9,07 10,16 11,26 12,39 13,85 7,82 1,08 1,06 1,06 1,06 1,07 1,08 1,09 1,10 1,12 1,46 2,66 3,75 4,81 5,88 6,94 8,02 9,10 10,20 11,30 12,43 13,90 7,84 1,08 1,07 1,06 1,06 1,08 1,08 1,10 1,11 1,13 1,47 2,67 3,76 4,83 5,89 6,96 8,04 9,13 10,23 11,34 12,48 13,95 7,86 1,09 1,07 1,07 1,07 1,08 1,09 1,10 1,11 1,13 1,47 Table 7: Model of predicted touch down times for male sprint hurdlers based on data from 100 athletes Page 9 of 10

10 1H 2H 3H 4H 5H 6H 7H 8H 9H 10H 100MH 60MH 2,49 3,46 4,40 5,32 6,25 7,17 8,09 9,03 9,98 10,96 12,00 7,54 0,97 0,94 0,92 0,93 0,92 0,92 0,94 0,94 0,98 1,04 2,50 3,47 4,41 5,34 6,27 7,20 8,12 9,07 10,02 11,00 12,05 7,56 0,97 0,94 0,93 0,93 0,92 0,93 0,95 0,95 0,98 1,05 2,50 3,48 4,43 5,36 6,30 7,22 8,16 9,11 10,06 11,04 12,10 7,59 0,98 0,95 0,93 0,94 0,93 0,93 0,95 0,95 0,99 1,06 2,51 3,49 4,44 5,38 6,32 7,25 8,19 9,14 10,10 11,09 12,15 7,62 0,98 0,95 0,93 0,94 0,93 0,94 0,95 0,96 0,99 1,06 2,51 3,50 4,46 5,40 6,34 7,28 8,22 9,18 10,14 11,13 12,20 7,64 0,99 0,96 0,94 0,94 0,94 0,94 0,96 0,96 0,99 1,07 2,52 3,51 4,47 5,42 6,36 7,30 8,25 9,21 10,18 11,18 12,25 7,67 0,99 0,96 0,94 0,95 0,94 0,95 0,96 0,97 1,00 1,07 2,53 3,52 4,49 5,44 6,39 7,33 8,28 9,25 10,22 11,22 12,30 7,69 0,99 0,97 0,95 0,95 0,95 0,95 0,97 0,97 1,00 1,08 2,53 3,53 4,50 5,45 6,41 7,36 8,32 9,29 10,26 11,27 12,35 7,72 1,00 0,97 0,95 0,95 0,95 0,96 0,97 0,98 1,00 1,08 2,54 3,54 4,52 5,47 6,43 7,39 8,35 9,32 10,30 11,31 12,40 7,74 1,00 0,98 0,96 0,96 0,95 0,96 0,97 0,98 1,01 1,09 2,55 3,55 4,53 5,49 6,46 7,41 8,38 9,36 10,35 11,36 12,45 7,77 1,01 0,98 0,96 0,96 0,96 0,97 0,98 0,99 1,01 1,09 2,55 3,56 4,55 5,51 6,48 7,44 8,41 9,39 10,39 11,40 12,50 7,79 1,01 0,98 0,97 0,97 0,96 0,97 0,98 0,99 1,02 1,10 2,56 3,57 4,56 5,53 6,50 7,47 8,44 9,43 10,43 11,45 12,55 7,82 1,01 0,99 0,97 0,97 0,97 0,98 0,99 1,00 1,02 1,10 2,56 3,58 4,58 5,55 6,52 7,50 8,48 9,47 10,47 11,49 12,60 7,84 1,02 0,99 0,97 0,97 0,97 0,98 0,99 1,00 1,02 1,11 2,57 3,59 4,59 5,57 6,55 7,52 8,51 9,50 10,51 11,53 12,65 7,87 1,02 1,00 0,98 0,98 0,98 0,98 1,00 1,01 1,03 1,12 2,58 3,60 4,61 5,59 6,57 7,55 8,54 9,54 10,55 11,58 12,70 7,90 1,03 1,00 0,98 0,98 0,98 0,99 1,00 1,01 1,03 1,12 2,58 3,62 4,62 5,61 6,59 7,58 8,57 9,57 10,59 11,62 12,75 7,92 1,03 1,01 0,99 0,98 0,99 0,99 1,00 1,02 1,03 1,13 2,59 3,63 4,64 5,63 6,61 7,60 8,60 9,61 10,63 11,67 12,80 7,95 1,04 1,01 0,99 0,99 0,99 1,00 1,01 1,02 1,04 1,13 2,60 3,64 4,65 5,65 6,64 7,63 8,64 9,65 10,67 11,71 12,85 7,97 1,04 1,01 1,00 0,99 1,00 1,00 1,01 1,03 1,04 1,14 2,60 3,65 4,66 5,66 6,66 7,66 8,67 9,68 10,71 11,76 12,90 8,00 1,04 1,02 1,00 0,99 1,00 1,01 1,02 1,03 1,04 1,14 2,61 3,66 4,68 5,68 6,68 7,69 8,70 9,72 10,75 11,80 12,95 8,02 1,05 1,02 1,00 1,00 1,00 1,01 1,02 1,04 1,05 1,15 2,62 3,67 4,69 5,70 6,70 7,71 8,73 9,75 10,79 11,85 13,00 8,05 1,05 1,03 1,01 1,00 1,01 1,02 1,02 1,04 1,05 1,15 2,62 3,68 4,71 5,72 6,73 7,74 8,76 9,79 10,84 11,89 13,05 8,07 1,06 1,03 1,01 1,01 1,01 1,02 1,03 1,05 1,06 1,16 2,63 3,69 4,72 5,74 6,75 7,77 8,79 9,83 10,88 11,94 13,10 8,10 1,06 1,04 1,02 1,01 1,02 1,03 1,03 1,05 1,06 1,16 2,63 3,70 4,74 5,76 6,77 7,80 8,83 9,86 10,92 11,98 13,15 8,13 1,06 1,04 1,02 1,01 1,02 1,03 1,04 1,06 1,06 1,17 2,64 3,71 4,75 5,78 6,80 7,82 8,86 9,90 10,96 12,03 13,20 8,15 1,07 1,04 1,03 1,02 1,03 1,04 1,04 1,06 1,07 1,17 2,65 3,72 4,77 5,80 6,82 7,85 8,89 9,93 11,00 12,07 13,25 8,18 1,07 1,05 1,03 1,02 1,03 1,04 1,04 1,07 1,07 1,18 Table 8: Model of predicted touch down times for female sprint hurdlers based on data from 85 athletes Page 10 of 10