High Jump technique

Apart from body height the critical factors in the high jump are the vertical take-off velocity and the efficiency of crossing the bar. Body height is important because the center of gravity (CG) of taller people already lies higher after take-off than that of smaller people. Women normally exceed their body height by a maximum of 25 cm, men by maximally 50 cm (the American Jacobs was 1.73 m tall and jumped 2.32 m, i.e. a difference of 59 cm).

The vertical take-off velocity determines how high the athlete flies.

Two aspects are important when crossing the bar; firstly the highest point of the CG path should be above the bar and not behind or below it (one reason why Kostadinova lost the Olympic final in Seoul was that the path of the CG passed 16 cm (!) behind the bar). The second aspect is that the CG path should pass as close as possible to the bar. The smallest measured differences in valid jumps are around 3 cm.

 

From a biomechanical perspective the ground surface is not as important as in the sprint or in other jumping events. The ground is more important for take-off than for the approach because the jumpers do not require a maximum approach speed.

Climatic conditions are instead important: high jumpers are especially at risk with a wet track because of the curved approach. In addition to this the approach of many high jumpers reaches into the running track. Simultaneous running events therefore, distract the athlete, especially in the concentration phase.

 

Similar to all other jumping events the high jump can be divided into approach, take-off preparation, take-off, flight and landing.

 

Approach: The aim of the approach is to achieve an optimal approach speed (7 - 8 m/s for men, 6 - 7.5 m/s for women) with high approach precision. Differences in speed depend upon the athletic capabilities of the jumpers. While greater speeds provide more energy for the jumper, they are only useful if this can be diverted into a vertical direction during the short take-off time.

The last curved portion of the approach is a unique characteristic of the flop. A historical anecdote states that the garden in which Dick Fosbury trained was very narrow and that the approach was obstructed by a tree. A more important aspect is, however, that a curved approach facilitates the required rotations about the three body axes.  

Each rotation requires energy which is usually produced during take-off and dissipated in the actual take-off impulse. The curve allows some of this energy to already by produced during the approach. Straightening up from the inward lean of the curve and bringing the swing elements towards the body center both produce rotational energy which therefore, does not have to be produced by the take-off leg during take-off.

 

Take-off preparation: This decisive phase of the high jump has the aim of providing optimal conditions for the take-off. There are mutual trends despite all the individual differences between jumpers: the stride rate increases in the last few strides with all top jumpers, the ground contact times increase and the flight phases get shorter. This is especially noticeable in the final step: the flight phase prior to planting the take-off foot is only 40 - 60 ms long. It is also noticeable that the lowest CG position is reached in the second to last step and not at take-off. The take-off basically already begins here.

 

Take-off: The aim of the take-off is to achieve the greatest possible vertical take-off velocity (men: 4.4 - 4.8 m/s; women: 3.6 - 4.1 m/s) which determines the flight height of the CG (men: 0.98 - 1.17 m; women: 0.66 - 0.89 m).The approach speed is reduced by about 50% at take-off which results in a take-off angle of approximately 45 - 55°. The take-off takes between 120 and 160 m/s which is the same for both sexes although men demonstrate a considerably longer acceleration path (averages of the finalists at the world championships in Tokyo, 1991; men: 53 cm , women: just under 46 cm) which indicates greater strength capabilities. The swing leg and arms assist the take-off by initially accelerating sharply and then being stopped just prior to leaving the ground.

The curved approach results in a problem specific to the high jump take-off: the take-off foot is forced into an extremely pronated position which places high loads upon the joints and ligaments.

 

Flight: The CG path after leaving the ground is set and can not be altered by any movements in the air. Differences in the climbing phase up to the bar (basically extended body position, more or less fixed position of the swing leg) are therefore, only important in so far as they influence either the take-off or the crossing of the bar. Movements executed by the jumper in the air can, however, still influence the height attained. Data showing that valid jumps have been performed in which the CG only cleared the bar by 3 cm, while invalid jumps are known from some world class athletes in which the CG actually cleared the bar by 15 cm indicates that an effective and well timed transfer of segmental centers of gravity can considerably influence performance variability.

The high jump is one of the most frequently analyzed events at international competitions despite the high measuring complexity necessary because the curved approach requires a three-dimensional analysis. Many data are therefore, available from the world’s best jumpers. Despite this it has not been possible to ascertain performance determining factor which apply universally to all jumpers.

The approach speed is not as influential as in other jumping events although the recently dominating athletes (Kostadinova, Henkel, Sotomayor) are amongst those with greater approach speeds. The stride length characteristics of the final strides is very variable but the stride rate is identical amongst top athletes. The lowering of the CG and the length of the acceleration path does not show clear patterns either. For example Sotomayor performs with a relatively long acceleration path while that of Kostadinova is generally very short.

The take-off time is not a valid factor either. Povarnyzin won Olympic gold in Seoul with 195 ms and Kostadinova silver with 115 ms which was, however, clearly too short.