Biomechanical analysis of drop jump performed on land and in water with different immersion levels

This study aimed to analyze the immersion level effect on kinetic and kinematic characteristics of depth jumps performed on land and in water at different immersion levels. Participants were 26 young male volleyball and track and field athletes (18.2 ± 2.6 years, 1.87 ± 0.1 m in height, and 74.8 ± 9.0 kg body mass). The analyzed variables were the maximum vertical force on the eccentric and concentric sub-phases of contact and landing, the impulse on the eccentric and concentric sub-phases, contact time, eccentric and concentric contact time, and jump flight time. Depth jumps from 0.4 m were executed on land and at four different immersion levels (tibia s midpoint, tibia s lateral condyle, thigh s midpoint and anterior superior iliac spine). A force platform connected to a data acquisition system, a 2-D electrogoniometer and a synchronizing device were used for data collection. Data were processed through specific routines in Scilab 4.1.2 software. Mean values were calculated from three repetitions of each subject in each analyzed condition, and the immersion level effect was analyzed through tests for repeated measures and their respective post-hoc (p <0 05). Results indicate that the higher the immersion level, the lower the values of maximum vertical force on the eccentric and concentric sub-phases of contact and on landing. However, lower levels of immersion (tibia s midpoint and tibia s lateral condyle) were not sufficient to reduce these forces in most cases. Overall, significant reductions of these variables compared with the land execution occurred from the immersion level of the thigh s midpoint. The increase of the immersion level resulted in impulse reduction during eccentric sub-phase and in a longer duration of this phase. However no difference was found between land and water conditions for concentric impulse and contact time. Higher levels of immersion resulted in longer contact time and flight time duration. Therefore, according to these results, due differences between the two environments, aquatic plyometric training may not be adequate to fully replace the plyometric training on land. Despite, aquatic plyometrics present excellent possibilities for training depending on the training purpose, competitive season stage, or the rehabilitation process characteristics. In any of these cases it is necessary to consider the immersion levels, musculoskeletal conditions and individual anthropometrics characteristics.O objetivo deste estudo foi analisar o efeito da imersão sobre as características cinéticas e cinemáticas de saltos em profundidade realizados no solo e na água com diferentes níveis de imersão. Participaram da pesquisa 26 atletas de voleibol e atletismo, do sexo masculino (18,2 ± 2,6 anos; 1,87 ± 0,1 m de altura; e 74,8 ± 9,0 kg de massa corporal). Foram analisados os valores máximos da força vertical nas subfases excêntrica e concêntrica do contato e na aterrissagem, o impulso nas subfases excêntrica e concêntrica, o tempo de contato, o tempo de contato excêntrico e concêntrico e o tempo de voo durante a execução de saltos em profundidade máximos partindo de 0,4 m no solo e em quatro diferentes níveis de imersão (ponto médio da tíbia, côndilo lateral da tíbia, ponto médio da coxa e espinha ilíaca ântero-superior). Foi utilizada uma plataforma de força conectada a um sistema de aquisição de dados, um eletrogoniômetro 2-D e um sincronizador de sinais. Os dados foram processados através de rotinas específicas no software Scilab 4.1.2. Foram calculados valores médios das três repetições de cada sujeito em cada uma das condições de análise, e o efeito do nível de imersão foi analisado a partir de estatística descritiva e inferencial através de testes para medidas repetidas e seus respectivos post-hoc (p