The Effect of Drop Jump Starting Height and Contact Time on Power, Work Performed, and Moment of Force

Abstract

The purposes of this study are (a) to examine the effects of contact time manipulation on jump parameters and (b) to examine the interaction between starting height changes and contact time changes on important jump parameters. Fifteen male athletes performed a series of drop jumps from heights of 20, 40, and 60 cm. The instructions given to the subjects were (a) "jump as high as you can" and (b) "jump high a little faster than your previous jump." Jumps were performed at each height until the athlete could not achieve a shorter ground contact time. The data were divided into 5 groups where group 1 was made up of the longest ground contact times of each athlete and groups 2-4 were composed of progressively shorter contact times, with group 5 having the shortest contact times. The jumps of group 3 produced the highest maximum and mean mechanical power (p <0.05) during the positive phase of the drop jumps regardless of starting jump height. The vertical takeoff velocities for the first 3 groups did not show significant (p < 0.05) differences. These results indicate that the manipulation of jump technique plays larger role than jump height in the manipulation of important jump parameters.

Landing Mechanics between Noninjured Women and Women with Anterior Cruciate Ligament Reconstruction during 2 Jump Tasks

“…10 The drop jump task is an ideal task to study landing strategies because of its ability to maximally create eccentric loading on the lower extremity. 46 The up-down is another task that has been recommended to be used to detect knee joint instability because of its high sensitivity value (.58). 20,21,31 The kinematic results of this investigation supported the overall null hypothesis by demonstrating that women with ACL reconstruction exhibited peak hip and knee joint angles similar to those of healthy, noninjured young women in both tasks.…”

A Comparison of Two Landing Styles in a Two-Foot Vertical Jump

“…The two-foot support vertical jump has been studied from a biomechanical viewpoint on many occasions and with different purposes: to evalúate different ways of muscle participation (3,15), to assess segmental participation (9,12,16), or to identify its determining efficieney factors (2,13,23). However, generally the jump is quantified based on the vertical component of the forcé from a stationary position, with or without a countermovement, or based on different heights, ignoring the effect on the takeoff phase produced by the run-up.…”

Análise biomecânica da fase de contato no salto em profundidade no solo e na água

“…According to Flanagan and Comyns 16 and Walsh et al 18 , training using exercises in which SSC is slowly performed may not be as beneficial for athletes who primarily need fast action in sports. According to Jurado-Lavanant et al 9 , one should take into account the principle of specificity: although plyometric training in water appears to be safer than plyometric training on land, where performance depends on the ability to immediately perform a maximum vertical jump towards a target (DJ) or the repetition of high-intensity actions (sequential rebound jumps), better results are probably achieved through plyometric training on dry land.…”

“…Since drop jump (DJ) is one of the exercises most widely used in plyometric training [16][17][18] , this study aimed to analyze and compare the vertical component of the ground reaction force and contact duration of DJ performed at hip immersion in water and on dry land.…”