Horizontal jumps
Abstract
A series of horizontal jumps made by the experienced male athlete was recorded with a piezoelectric force plate (PFP) and velocity using a high-speed video camera. The velocity range of the athlete was obtained by using both electromyography (EMG) and direct intervention by setting the length of run-up. During this humping period, the horizontal velocity was considerably decreased at the point of take-off. The breaking impulse of the athlete was found to be increasing with an increase in velocity. However, the take-off technique was varied between the desires of generating vertical impulse and reducing the horizontal breaking impulse. The main objective study was, therefore, to correlate the effect of knee joint with take-off force.
Keywords: Long Jump, take-off force, take-off velocity, take-off technique, and take-off impulse and electromyography
Introduction
The distance covered by an athlete in a long-jump race depends directly on the velocity at the end of run-up. However, to maximize run-up velocity, the athlete needs to produce enough energy during take-off to enables them thrush forward with high take-off velocity. The athlete needs to generate vertical velocity at a higher rate so to reduce the horizontal velocity. Doing so enables the athlete to thrust forward with a higher vertical velocity hence covering a larger horizontal distance. Furthermore, the athlete needs to lower the center of mass at the take-off stride and thrush the foot forward ahead of the center of mass. The legs should be extended at an angle of about 600 to 650. The body parts of the jumper then swivel up over the take-off foot as the leg flexes and retract rapidly. The technique is referred to as an optimum take-off technique, which generates a high vertical velocity of about 3.4m/s for the case of men and 3.1m/s for ladies. It also retains a high proportion of horizontal velocity at the take-off of about 8.8m/s for men and 8.0m/s for females. The take-off angle produced by the technique is about 210. However, there are four main features of the horizontal jump: the run-up velocity, the last two strides, take-off force, and landing. The take-off velocity and high vertical velocity are the essential elements of success in this race. Since velocity is a factor of success in the long jump, most of the competitors in long jumps also excels in sprinting. Carl Lewis of the USA is a typical example of a sprinter who also takes part in long jump races
However, Some Coaches and biomechanics have suggested the use of force plates to monitor the take-off force of athletes during long jump race. The technique is ideal as it provide the response to the athletes hence improves their take-off force during training. However, for this to be effective, we need to understand the relationship between the run up, take off force and the horizontal distance covered. To understand these relations, we need to conduct an intervention in which the take-off velocity of the athlete is varied with the run up distance. As the athlete run up, his take-off velocity and the run up distance increases. However, the take-off angle and the take-off duration reduces. Here, we report the findings obtained by using force plate to measure the impulse and take-off force of an athlete.
Method
In the experiment, a male athlete of age 22 years, height 1.7m, weight 58kg and personal best 5.81m conducted series of long jump. The run up length used were 2, 4, 8, 12, and 16 strides. Both horizontal and vertical reactions component of forces were obtained using piezoelectric force plate (PFP) set at a frequency of 1000Hz. The video images of the athlete were captured using JCV GR9800 camera operating at a frequency of 100Hz. The motion of the athlete was obtained by using a digitalized Ariel in the video image. However, the vertical and horizontal velocities during take-off were obtained through calculating the data formed on the piezoelectric force plate. The information from the video was also used to obtain other variables such as the center of mass of the athlete, the horizontal position of the athlete, and the knee angle.