A hiperextensão dos joelhos pode comprometer o controle postural durante o salto vertical. Desta forma, o objetivo deste estudo foi analisar o deslocamento do Centro de Pressão (CP) e o movimento em membros inferiores durante o salto vertical de sujeitos com joelhos hiperestendidos comparativamente com sujeitos com joelhos alinhados no período de preparo do salto. Dezesseis mulheres foram analisadas durante o salto vertical, através de uma plataforma de força modelo AMTI. Os sujeitos foram enquadrados nos grupos Sujeito-Hiperestendido (n=11) e Sujeito-Alinhados (n=5) de acordo com o alinhamento dos joelhos na avaliação postural tradicional e a análise dos dados cinématicos foram efetuadas. Os sujeitos foram orientados a se posicionar sobre uma plataforma de força e saltar o mais alto possível. A cinemática foi adquirida através de câmera em posição padronizada ao lado direito do sujeito que teve os seguintes pontos anatômicos marcados: 5º metatarso, maléolo lateral, cabeça da fíbula e trocânter maior. A fase de preparo e de impulso, neste estudo chamado de fase de preparo, foi determinada pela curva de velocidade angular do joelho. A aterrissagem foi analisada no 1s, 2s e 3s após aterrissagem. Foram calculados para comparação o CP-AP, o CP-ML e o ângulo e velocidade angular máxima e mínima do tornozelo e joelho. Comparação intergrupos dos intervalos de interesse foi realizada aplicando-se Teste de Mann- Whitney aos dados (p<0.05). Comparação intragrupo, entre os intervalos de interesse foi realizada aplicando-se o teste de Friedman seguido do teste de Wilcoxon (p<0.05). Este estudo revelou que indivíduos com hiperextensão de joelhos apresentam controle postural diferente dos com joelhos alinhados durante a execução do salto vertical. Durante a fase de preparo os indivíduos com joelhos hiperextendidos apresentam maior ângulo de extensão de joelhos e maior deslocamento lateral do COP. Durante a fase de aterrissagem os indivíduos com joelhos hiperextendidos apresentam maior ângulo de extensão e menor ângulo de flexão demandando menor deslocamento lateral do COP do que os indivíduos alinhados / Postural misalignment of knee such as hyperextended knees may compromise postural control during vertical jump. Therefore, the aim of this study was to analyze COP and lower limbs movements during vertical jump comparing individuals with hyperextended and aligned knees. Sixteen young and healthy women were analyzed during their maximal vertical jump using a MTI force plate. Subjects were classified as hyperextended (n=11) or aligned (n=5) knees according to clinical observation of knee angle. Subjects were asked to stand still on the force plate and then jump as high as possible. Kinematic data were acquired using a camera located in standardized position at the right side of the subject. Anatomical landmarks were placed at the right side at: 5º metatarsal, lateral malleolus, head of fibula and greater throcanter. The phase of preparation associated to the phase of propulsion was called in this study the phase of preparation. This phase was established based on the curve of angular velocity of the knee. Landing was analyzed in the first, second and third second immediately after landing. COP-AP, VM-AP, COPML and VM-ML were calculated. Kinematic parameters were maximum and minimum ankle and knee angle and angular velocity. Intergroup comparison was carried using Mann-Whitney Test (p<0.05). Intergroup comparison was carried using Friedman Test followed by Wilcoxon Test (p<0.05). This study revealed that subjects with hyperextended knee present different postural control compared to the subjects with aligned knees while performing a vertical jump. During the phase of preparation subjects with hyperextended knees revealed higher angle of knee extension and lower COP-ML displacement. During the phase of landing subjects with hyperextended knees present higher angle of knee extension and lower angle of knee flexion requiring lower displacement of COP-ML when compared to subjects with aligned knee

O objetivo do estudo foi investigar o construto da tarefa de múltiplas acelerações a partir de parâmetros biomecânicos de saltos verticais. 19 jogadoras da seleção brasileira adulta de basquetebol feminino realizaram o teste de múltiplas acelerações (teste T), salto vertical com contramovimento (SV) e salto vertical com contramovimento precedido de corrida (SVcorrida). Os parâmetros biomecânicos do SV foram, tempo de fase concêntrica (Tcon), pico de força de propulsão (PFP), tempo decorrido entre início da fase concêntrica e o pico de força de propulsão (TPFP), taxa de desenvolvimento de força (TDF) e impulso (I); para SVcorrida, velocidade média de aproximação (Velmédia), tempo total do movimento (Ttotal), pico de força passiva (PFPa), tempo decorrido entre início da fase de apoio e pico de força passiva (TPFPa), pico de força de propulsão (PFP), tempo decorrido entre início da fase de apoio e pico de força de propulsão (TPFPp), Load Rate (LR) e taxa de desenvolvimento de força (TDF). Para análise dos dados, inicialmente, recorreu-se a análise de componentes principais, revelando que 61,3% da variância total do SV foi explicada pelo componente predominantemente temporal (Tcon, TPFP e PFP) e 20,7% pelo componente predominantemente cinético (I e TDF); para SVcorrida, 58,7% da variância total foi explicada pelo componente predominantemente temporal (Ttotal, TPFPa, TPFPp, LR e TDF), 15,4% pelo componente predominantemente cinético (PFPa e PFP) e 12,8% pelo componente velocidade (Velmédia). Adicionalmente, foram reveladas correlações significantes de 0,55 (Tcon), -0,54 (Velmédia) e -0,49 (PFP) com o teste T, evidenciando um construto determinado pela capacidade de se gerar elevada força na fase concêntrica, reduzir o tempo de fase concêntrica e se aproximar do ponto de mudança de direção com elevada velocidade. / The main aim of the study was to investigate the multiple-acceleration task construct from vertical jumps biomechanics parameters. Nineteen female basketball players from Brazilian national team performed the multiple-acceleration test (T test), countermovement jump (VJ) and countermovement jump preceded by run (VJr). The VJ biomechanics parameters observed were: concentric phase duration (CPD), propulsion peak force (PPF), time to reach propulsion peak force (TPPF), rate of force development (RFD) and impulse (I); for VJr the parameters were mean velocity (MV), movement total duration (MTD), passive peak force (PaPF), time to reach passive peak force (TPaPF), propulsion peak force (PPF), time to reach propulsion peak force (TPpPF), load rate (LR) and rate of force development (RFD). Data were first analyzed by principal component analysis. The results showed that 61.3% of VJ variance could be explained by time factor (CPD, TPPF and PPF), and 20.7% by kinetic factor (I and RFD). To VJr, 58.7% of total variance could be explained by time factor (MTD, TPaPF, TPpPF, LR, RFD) and 15.4% by kinetic factor (PPF and PaPF) and 12.8% by velocity factor (MV). Furthermore, significant correlations were found between T test with CPD, MV and PPF (0.55, -0.54 and -0.49, respectively), revealing a T test construct related to the ability of generating high level of force in concentric phase, diminishing time of concentric phase, and to reach the change direction point with greatest possible speed.

A hiperextensão dos joelhos pode comprometer o controle postural durante o salto vertical. Desta forma, o objetivo deste estudo foi analisar o deslocamento do Centro de Pressão (CP) e o movimento em membros inferiores durante o salto vertical de sujeitos com joelhos hiperestendidos comparativamente com sujeitos com joelhos alinhados no período de preparo do salto. Dezesseis mulheres foram analisadas durante o salto vertical, através de uma plataforma de força modelo AMTI. Os sujeitos foram enquadrados nos grupos Sujeito-Hiperestendido (n=11) e Sujeito-Alinhados (n=5) de acordo com o alinhamento dos joelhos na avaliação postural tradicional e a análise dos dados cinématicos foram efetuadas. Os sujeitos foram orientados a se posicionar sobre uma plataforma de força e saltar o mais alto possível. A cinemática foi adquirida através de câmera em posição padronizada ao lado direito do sujeito que teve os seguintes pontos anatômicos marcados: 5º metatarso, maléolo lateral, cabeça da fíbula e trocânter maior. A fase de preparo e de impulso, neste estudo chamado de fase de preparo, foi determinada pela curva de velocidade angular do joelho. A aterrissagem foi analisada no 1s, 2s e 3s após aterrissagem. Foram calculados para comparação o CP-AP, o CP-ML e o ângulo e velocidade angular máxima e mínima do tornozelo e joelho. Comparação intergrupos dos intervalos de interesse foi realizada aplicando-se Teste de Mann- Whitney aos dados (p<0.05). Comparação intragrupo, entre os intervalos de interesse foi realizada aplicando-se o teste de Friedman seguido do teste de Wilcoxon (p<0.05). Este estudo revelou que indivíduos com hiperextensão de joelhos apresentam controle postural diferente dos com joelhos alinhados durante a execução do salto vertical. Durante a fase de preparo os indivíduos com joelhos hiperextendidos apresentam maior ângulo de extensão de joelhos e maior deslocamento lateral do COP. Durante a fase de aterrissagem os indivíduos com joelhos hiperextendidos apresentam maior ângulo de extensão e menor ângulo de flexão demandando menor deslocamento lateral do COP do que os indivíduos alinhados / Postural misalignment of knee such as hyperextended knees may compromise postural control during vertical jump. Therefore, the aim of this study was to analyze COP and lower limbs movements during vertical jump comparing individuals with hyperextended and aligned knees. Sixteen young and healthy women were analyzed during their maximal vertical jump using a MTI force plate. Subjects were classified as hyperextended (n=11) or aligned (n=5) knees according to clinical observation of knee angle. Subjects were asked to stand still on the force plate and then jump as high as possible. Kinematic data were acquired using a camera located in standardized position at the right side of the subject. Anatomical landmarks were placed at the right side at: 5º metatarsal, lateral malleolus, head of fibula and greater throcanter. The phase of preparation associated to the phase of propulsion was called in this study the phase of preparation. This phase was established based on the curve of angular velocity of the knee. Landing was analyzed in the first, second and third second immediately after landing. COP-AP, VM-AP, COPML and VM-ML were calculated. Kinematic parameters were maximum and minimum ankle and knee angle and angular velocity. Intergroup comparison was carried using Mann-Whitney Test (p<0.05). Intergroup comparison was carried using Friedman Test followed by Wilcoxon Test (p<0.05). This study revealed that subjects with hyperextended knee present different postural control compared to the subjects with aligned knees while performing a vertical jump. During the phase of preparation subjects with hyperextended knees revealed higher angle of knee extension and lower COP-ML displacement. During the phase of landing subjects with hyperextended knees present higher angle of knee extension and lower angle of knee flexion requiring lower displacement of COP-ML when compared to subjects with aligned knee

The purposes of this dissertation were to examine bilateral asymmetry as a factor of postactivation potentiation, examine and compare the acute effects of ballistic and non-ballistic concentric-only half-squats on squat jump performance, and compare the potentiation and temporal profiles of strong and weak subjects following potentiation protocols that included ballistic and non-ballistic concentric-only half-squats. The following are major findings of the dissertation. Squat jump performance may be acutely enhanced following ballistic concentriconly half-squats; however the changes in performance do not appear to be related to bilateral symmetry. Ballistic concentric-only half-squats acutely improve various squat jump performance variables at various time intervals; however the changes in performance are not related to the bilateral symmetry of the subject. Ballistic concentric-only half-squats produced superior acute potentiation effects with regard to jump height, peak power, and allometricallyscaled peak power as compared to non-ballistic concentric-only half-squats and a control protocol. Stronger subjects potentiated earlier and to a greater extent as compared to their weaker counterparts. This dissertation indicates that bilateral symmetry may not be considered as an underlying factor affecting postactivation potentiation. However, it is suggested that future research should continue to investigate the factors that are associated with postactivation potentiation. The findings of this dissertation also demonstrate the importance of how an individual performs a concentric-only squatting motion. By training with ballistic movements, a greater training stimulus may be achieved as compared to training with non-ballistic movements. While this dissertation discussed the acute potentiation differences between ballistic and nonballistic concentric-only half-squats, longitudinal research is needed to determine if different training effects result from each training method. This dissertation also supports that notion that stronger individuals may benefit more with regard to potentiation effects. In order to optimize performance and realize the greatest potentiation effects, it is recommended that greater levels of relative strength should be sought. It is suggested that further research is needed on the longitudinal differences in the potentiation effects an individual can realize based on their strength levels.

The purposes of this dissertation were to examine the phase characteristics of the countermovement jump force-time curve between athletes based on jumping ability, examine the influence of maximal muscular strength on the countermovement jump force-time curve phase characteristics of athletes, and to examine the behavior of the countermovement jump force-time curve phase characteristics over the course of a training process in athletes of varying strength levels. The following are the major findings of these dissertations. The analysis of athletes by jumping ability suggested that proficient jumpers are associated with greater relative phase magnitude and phase impulse throughout the phases contained in the positive impulse of the countermovement jump force-time curve. Additionally, phase duration was not found to differ between athletes based on jumping ability or between male and female athletes. The analysis of athletes based on maximal muscular strength suggested that only unweighted phase duration differs between strong and less-strong athletes. Interestingly, in both investigations based on jumping ability and maximal strength indicated the relative shape of the stretching phase representing the rise in positive force was related to an athlete’s jumping ability (jump height). The results of the longitudinal analysis of countermovement jump force-time phase characteristics identified that these variables can be frequently assessed throughout a training process to provide information of regarding an athlete performance state. Furthermore, based on the contrasting behaviors of many of the countermovement jump force-time curve phase characteristics over time, an athlete’s level of muscular strength may influence how these characteristics are expressed in the context of a training process.

The isometric mid-thigh pull (IMTP) has been cited often in the scientific literature; however, there is still a lack of agreement as to the ideal body position used during this test, and how body position impacts the relationship between IMTP performance and dynamic performance. Thus, one aim of this dissertation was to compare two different IMTP positions and correlate the kinetic outputs from each position to vertical jump (VJ) performance. Another purpose of this dissertation was analyze which method of data normalization for IMTP force variables best correlates to squat jump (SJ) and countermovement jump (CMJ) performance. In the first study, subjects presented higher force outputs for an upright position (hip angles 145°, knee 125°) when compared to a bent position (hip angles 125°, knee 125°). However, there were no statistical differences among correlations from the two positions when correlating to VJ performance. Thus, we suggest that the upright position should be the one used for research and monitoring due to higher force values presented. The second part of this study was to compare correlations from non-normalized and normalized data from the IMTP to SJ and CMJ. Besides non-normalized data, five common methods of normalization were used – subtracting the body mass force, dividing the forces per body mass, allometric scale, scaling by height (Ford’s scale) and scaling by Sinclair coefficient value. In general, higher value correlations were presented with the non-normalized methods for both jumps – SJ and CMJ. Therefore, when using IMTP data to correlate with VJ performance, there is no need to normalize the data.

Low-head dams are capable of creating dangerous counter-currents just downstream from the structure. These dangerous counter-currents are known as submerged hydraulic jumps and are responsible for hundreds of fatalities at numerous low-head dams across the United States. The counter-current creates high upstream-directed surface velocities across the width of the channel, making it nearly impossible for an individual to escape. This submerged jump can occur during a range of upstream and downstream conditions. Effective, safe and low-cost remediation options must be explored in order to prevent further fatalities at these structures. This document explores such a remediation option: the Multiple Staggered Deflector Design. This remediation option will disrupt uniform upstream-directed surface velocities across the channel within a submerged jump for nearly all downstream conditions that create a submerged jump for a range of upstream conditions. The dam modification is designed such that an individual will escape the submerged jump without severe injury or harm, while being relatively inexpensive and simple to install.

The purpose of this study was to examine the influence of accumulated volume load on countermovement jump (CMJ) mechanical variables. Eight athletes underwent weekly CMJ testing using a force plate. Statistical changes were observed in certain CMJ variables over the observation period. Jump height (0.42±0.05 m) and allometrically scaled peak power (88.86±7.49 W·kg-0.67) exhibited multiple statistical changes. These changes appeared to exhibit a delayed effect in response to accumulated volume load. Specifically, following several weeks of large accumulated volume loads these variables declined. In addition subsequently decreasing accumulated volume loads resulted in an increase in both variables. The findings of this study indicate measuring jump height and peak power may be an effective method for monitoring a resistance training process.

S.S. Sastry, C. Desoer and P. Varaiya. / Bibliography: leaf 4. / Caption title. "August, 1981." / Supported by DOE under Grant ET-A01-2295T050 NSF Grant ENG-78-09032-A01

S.S. Sastry, C. Desoer and P. Varaiya. / Bibliography: leaf 4. / Caption title. "August, 1981." / Supported by DOE under Grant ET-A01-2295T050 NSF Grant ENG-78-09032-A01