Maximum Jumping Research Articles

Control strategy of maximum vertical jumps: The preferred countermovement depth may not be fully optimized for jump height.

The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles.

The effect of marker reconstruction noise on kinematics and kinetics in the gait of typically developing children

The purpose of this study was to investigate the emergence and stability of coordination patterns in children with developmental coordination disorder (DCD) when performing a rhythmic interlimb coordination task on rigid (floor) and elastic (mini-trampoline) surfaces. Twelve typically developing (TD) children and 12 children with DCD were required to clap while jumping under different conditions: in a chosen pattern – Free; when the feet touched the surface – Clapping-surface; when the body reached the maximum jumping height – Clapping-jump; and when the feet touched the surface and the body reached the maximum jumping height – Clapping-both. The results showed that the coordination pattern of children with DCD was more variable in the Free, Clapping-surface, and Clapping-jumping conditions and more variable on the mini-trampoline than on the floor under the Free condition when compared with the TD children. Clapping-jumping was more difficult to perform than Clapping-surface for both groups. These findings suggest that the children with DCD were less capable of rhythmically coordinating the jumping-clapping task because they used a type of exploratory strategy regarding the physical properties of the surfaces, whereas the TD children used a type of adaptive strategy displaying behavior that was more consistent across the tasks/environmental demands.

Fast Regulation of Vertical Squat Jump during Push-Off in Skilled Jumpers.

The height of a maximum Vertical Squat Jump (VSJ) reflects the useful power produced by a jumper during the push-off phase. In turn this partly depends on the coordination of the jumper's segmental rotations at each instant. The physical system constituted by the jumper has been shown to be very sensitive to perturbations and furthermore the movement is realized in a very short time (ca. 300 ms), compared to the timing of known feedback loops. However, the dynamics of the segmental coordination and its efficiency in relation to energetics at each instant of the push-off phase still remained to be clarified. Their study was the main purpose of the present research. Eight young adult volunteers (males) performed maximal VSJ. They were skilled in jumping according to their sport activities (track and field or volleyball). A video analysis on the kinematics of the jump determined the influence of the jumpers' segments rotation on the vertical velocity and acceleration of the body mass center (MC). The efficiency in the production of useful power at the jumpers' MC level, by the rotation of the segments, was measured in consequence. The results showed a great variability in the segmental movements of the eight jumpers, but homogeneity in the overall evolution of these movements with three consecutive types of coordination in the second part of the push-off (lasting roughly 0.16 s). Further analyses gave insights on the regulation of the push-off, suggesting that very fast regulation(s) of the VSJ may be supported by: (a) the adaptation of the motor cerebral programming to the jumper's physical characteristics; (b) the control of the initial posture; and (c) the jumper's perception of the position of his MC relative to the ground reaction force, during push-off, to reduce energetic losses.

Apex height control of a two-mass robot hopping on a rigid foundation

The spring loaded inverted pendulum (SLIP) model is commonly used to describe the dynamics of hopping robots. A fundamental limitation of the SLIP model is that it fails to account for impact with the ground; this is due to the fact that the leg is modeled as a massless spring. Assuming that the ground is rigid, a two-mass model with inelastic impact is proposed for more accurate description of hopping dynamics. A control scheme is developed to converge the maximum jumping height of the center-of-mass of the robot to a desired value. The control scheme utilizes feedback linearization in continuous time and update of a control parameter in discrete time. Simulation results are first presented to show the efficacy of the control scheme. Experimental results based on a voice-coil actuator show good match with simulation results despite actuator saturation.

Two-Load Method for Distinguishing Between Muscle Force, Velocity, and Power-Producing Capacities.

It is generally accepted that muscles may have different mechanical capacities, such as those for producing high force (F), velocity (V), and power (P) outputs. Nevertheless, standard procedures for evaluation of muscle function both in research and in routine testing are typically conducted under a single mechanical condition, such as a single external load. Therefore, the observed outcomes do not allow for distinguishing between the different muscle capacities. As a result, the outcomes of most routine testing procedures are of limited informational value, whereas a number of issues debated in research have originated from arbitrarily interpreted experimental findings regarding specific muscle capacities. A solution for this problem could be based on the approximately linear and exceptionally strong F-V relationship typically observed from various functional tasks performed under different external loads. These findings allow for the 'two-load method' proposed here: the functional movement tasks (e.g., maximum jumping, cycling, running, pushing, lifting, or throwing) should be tested against just two distinctive external loads. That is, the F-V relationship determined by two pairs of the F and V data could provide the parameters depicting the maximum F (i.e., the F-intercept), V (V-intercept), and P (calculated from the product of F and V) output of the tested muscles. Therefore, the proposed two-load method applied in both research and routine testing could provide a deeper insight into the mechanical properties and function of the tested muscles and resolve a number of issues debated in the literature.

Maximum height and minimum time vertical jumping

The performance criterion in maximum vertical jumping has typically been assumed to simply raise the center of mass as high as possible. In many sporting activities minimizing movement time during the jump is likely also critical to successful performance. The purpose of this study was to examine maximum height jumps performed while minimizing jump time. A direct dynamics model was used to examine squat jump performance, with dual performance criteria: maximize jump height and minimize jump time. The muscle model had activation dynamics, force–length, force–velocity properties, and a series of elastic component representing the tendon. The simulations were run in two modes. In Mode 1 the model was placed in a fixed initial position. In Mode 2 the simulation model selected the initial squat configuration as well as the sequence of muscle activations. The inclusion of time as a factor in Mode 1 simulations resulted in a small decrease in jump height and moderate time savings. The improvement in time was mostly accomplished by taking off from a less extended position. In Mode 2 simulations, more substantial time savings could be achieved by beginning the jump in a more upright posture. However, when time was weighted more heavily in these simulations, there was a more substantial reduction in jump height. Future work is needed to examine the implications for countermovement jumping and to examine the possibility of minimizing movement time as part of the control scheme even when the task is to jump maximally.

Sex differences in unilateral landing mechanics from absolute and relative heights

BackgroundThe prevalence of anterior cruciate ligament injuries in athletic populations and the sex disparity in injury rates are well documented. It is also recognized that landing from a jump is a common noncontact injury mechanism. Yet, most studies utilize absolute landing heights, and few have utilized landing heights equal to participants' maximal jumping ability. The purpose of this study was to examine unilateral landing mechanics from relative and absolute heights. MethodsTwenty-one female and twenty male participants completed a series of landings from absolute heights of 30, 40, and 50cm, as well as a height equal to their maximum jumping ability. Right leg three-dimensional kinematics, kinetics, and energetics were calculated from initial contact to maximum knee flexion. ResultsFemales landed with greater peak posterior ground reaction force compared to males. Additionally, both female and male participants utilized the knee as the primary energy absorber, but females appear to emphasize greater ankle energy absorption compared to males. Females also displayed increased peak knee adduction moment, while males displayed decreased peak hip abduction moment as landing height increased. ConclusionsIt appears that females and males respond to increasing landing heights differently. However, landings from 40 and 50cm may have represented an unrealistic mechanical demand for females, and influence subsequent inferences regarding ACL injury risk. Therefore, we suggest that comparisons between studies utilizing different landing heights be made with caution, and participants jumping ability be taken into account whenever possible. Clinical relevanceThe findings of this study offer novel insights with regard to landing height and lower extremity mechanics with the potential to inform anterior cruciate ligament injury intervention programs.

3D multiphase lattice Boltzmann simulations for morphological effects on self-propelled jumping of droplets on textured superhydrophobic surfaces

Coalescence induced droplets self-propelled jumping on textured superhydrophobic surfaces (SHS) is numerically simulated using multiple–relaxation–time (MRT), and three dimensional (3D) multiphase isothermal lattice Boltzmann method. Symmetric boundary conditions and parallel computation with OpenMP algorithm are used to accelerate computational speeds. Simulation results for velocity field show that the downward velocity of the droplet is reverted to upward direction due to the counter action of the wall to the contact base of the droplet during the period of droplet deformation on the texture. For a fixed droplet diameter, the spacing of the microstructure is found to play a key role on jumping velocity of the coalescence droplet, and an optimal spacing of the microstructure exists for a maximum jumping velocity. For a texture with small spacings, the adhesion force due to surface tension is large because of the large contact area which results in a decrease of its jumping velocity. On the other hand, for a texture with large roughness spacings, the lower contour of the droplet will fall into the texture, which will also decrease droplet jumping velocity. Simulation results for jumping velocities are used to explain large differences in measured jumping velocities of small droplets (with radius less than 20μm) on hierarchical textured and nanostructured surfaces in existing experiments.

Effects of countermovement depth on kinematic and kinetic patterns of maximum vertical jumps

Although maximum height (Hmax), muscle force (F), and power output (P), have been routinely obtained from maximum vertical jumps for various purposes, a possible role of the countermovement depth (Hcmd) on the same variables remains largely unexplored. Here we hypothesized that (1) the optimum Hcmd for maximizing Hmax exists, while (2) an increase in Hcmd would be associated with a decrease in both F and P. Professional male basketball players (N=11) preformed maximum countermovement jumps with and without arm swing while varying Hcmd±25cm from its preferred value. Although regression models revealed a presence of optimum Hcmd for maximizing Hmax, Hmax revealed only small changes within a wide range of Hcmd. The preferred Hcmd was markedly below its optimum value (p<.05). However, both F and P sharply decreased with Hcmd, while F also revealed a minimum for Hcmd close to its highest values. Therefore, we conclude that although the optimum Hcmd should exists, the magnitude of its effect on Hmax should be only minimal within a typical Hcmd range. Conversely, F and P of leg muscles assessed through maximum vertical jumps should be taken with caution since both of them could be markedly confounded by Hcmd.

Impact of global warming at the range margins: phenotypic plasticity and behavioral thermoregulation will buffer an endemic amphibian.

When dispersal is not an option to evade warming temperatures, compensation through behavior, plasticity, or evolutionary adaptation is essential to prevent extinction. In this work, we evaluated whether there is physiological plasticity in the thermal performance curve (TPC) of maximum jumping speed in individuals acclimated to current and projected temperatures and whether there is an opportunity for behavioral thermoregulation in the desert landscape where inhabits the northernmost population of the endemic frog Pleurodema thaul. Our results indicate that individuals acclimated to 20°C and 25°C increased the breath of their TPCs by shifting their upper limits with respect to when they were acclimated at 10°C. In addition, even when dispersal is not possible for this population, the landscape is heterogeneous enough to offer opportunities for behavioral thermoregulation. In particular, under current climatic conditions, behavioral thermoregulation is not compulsory as available operative temperatures are encompassed within the population TPC limits. However, for severe projected temperatures under climate change, behavioral thermoregulation will be required in the sunny patches. In overall, our results suggest that this population of Pleurodema thaul will be able to endure the worst projected scenario of climate warming as it has not only the physiological capacities but also the environmental opportunities to regulate its body temperature behaviorally.

Application of biological feedback for estimation of anaerobic performance in jumping test

Purpose : - To determine the effect of biofeedback to determine the level of anaerobic performance of healthy young men. Material: The characteristics of physical performance in 60-seconds jumping test without and with visual and audible biofeedback (BFB) are determined at 23 healthy young men. Results : Significant individual peculiarities are found in performance features of 60-seconds jumping test both without and with BFB. The groups of performance indexes are maximum jumping height; jumping frequency and achieved performance level; correlation of jumping phases and achieved capacity of a separate jump; jumping dynamics during the test. The positive effect mostly on performance in BFB regime is found in the group of persons with low level of physical performance. Conclusion : The application of BFB in 60-seconds jumping test is proved to increase the objective character of measuring anaerobic performance.

Body Composition and Muscle Strength Predictors of Jumping Performance

Studies of the role of various anthropometric, physiological, and biomechanical variables in performance of rapid movements have generally revealed inconsistent findings. Within this study, we tested the hypotheses that (a) both body composition and leg extensor strength variables would reveal significant relationship with jumping performance, whereas (b) the same relationships would be stronger in physically active nonathletes than in the elite athletes proficient in vertical jumping. Top-level female volleyball players (VP; N = 35) and physically active female nonathletes (PA; N = 21) were tested on maximum vertical jumps performed with and without arm swing, as well as on body composition (percent fat and muscle) and leg press strength (maximum force and the rate of force development). The results revealed significant relationships between the jumping performance and body composition variables that appeared to be higher in PA (r = 0.65-0.76; all p < 0.01) than in VP (r = 0.37-0.42; all p ≤ 0.05). The relationships between the jumping performance and the leg strength variables were mainly significant (r = 0.23-0.68) and similar in 2 groups. We conclude that not only the leg extensor strength but also the body composition variables could be valid predictors of jumping performance and, possibly, other rapid movements. Moreover, the body composition variables that have been mainly neglected in the literature could be particularly strong predictors of performance of jumping in nonathletes, as compared with relatively homogeneous populations of elite athletes.

Multiplanar breast kinematics during different exercise modalities

Multiplanar breast movement reduction is crucial to increasing physical activity participation amongst women. To date, research has focused on breast movement during running, but until breast movement is understood during different exercise modalities, the breast support requirements for specific activities are unknown. To understand breast support requirements during different exercise modalities, this study aimed to determine multiplanar breast kinematics during running, jumping and agility tasks. Sixteen 32D participants had markers attached to their right nipple and torso. Relative multiplanar breast displacement was calculated during bare-breasted treadmill running (10 kph), maximum countermovement jumping and an agility t-test. Exercise modality influenced the magnitude and direction of breast displacement, velocity and acceleration (p < .05). Jumping produced greater vertical breast displacement (.09 m) but less mediolateral breast displacement (.05 m) than running or the agility task, but agility tasks produced the highest multiplanar breast velocities and acceleration. Breast movement during jumping was predominantly in the vertical direction, whereas the agility task produced a greater percentage of mediolateral breast acceleration than running or jumping. Exercise modality impacted upon the magnitude and distribution of bare-breasted multiplanar breast kinematics in this homogenous 32D cohort. Therefore, to reduce breast movement in women of a 32D bra size, manufacturers may wish to design sport-specific products, with greater vertical support for exercise modalities incorporating jumping and greater mediolateral support for agility tasks.

Efeito de diferentes durações do alongamento no desempenho de saltos unipodais

INTRODUÇÃO: A prática de exercícios de alongamento é muito comum como parte do aquecimento em diversas modalidades esportivas, porém, esta prática pode ser negativa para aqueles que desejam o aprimoramento da força e potência muscular, consequentemente, o rendimento dos saltos pode ficar reduzido após exercícios de alongamento, que depende do tempo de duração e intensidade do mesmo.OBJETIVO: Avaliar a influência do tempo de permanência no exercício alongamento sobre o desempenho do drop jump unilateralmente (unipodal).MÉTODOS: A amostra foi composta por 16 adultos jovens hígidos, com larga experiência em saltos. O protocolo de teste consistiu em realizar três drop jumps unipodais máximos a partir de uma plataforma de 15 cm sobre um tapete de salto (Hidrofit(r)), antes e após duas durações (i.e. uma série 3 min. de um lado, e 6 min. para outro, a escolha foi de forma aleatória) de alongamento dos músculos tríceps sural, utilizando uma intensidade entre 70-90% da percepção subjetiva de desconforto. A análise de variância ANOVA (2x2) foi utilizada para verificar diferenças para a altura de salto, tempo de contato e flexibilidade, utilizando um nível de significância de 5%.RESULTADOS: Apresentaram diferenças significativas entre condições pré e pós-alongamento para as durações de 3 e 6 minutos (P=0,002 e P=0,001, respectivamente), com a diminuição na altura máxima do salto. O tempo de contato foi maior apenas para a duração de 6 minutos (P=0,039).CONCLUSÃO: A realização de exercícios de alongamento do músculo tríceps sural por 3 ou 6 minutos de duração resulta na queda do desempenho do drop jumpunipodal, diminuição da altura do salto vertical (para 3 e 6 min. de duração) e tempo de contato (apenas 6' min.), reforçando a necessidade de mais debates na área sobre exercícios de alongamento antes daqueles de potência.

Force-velocity relationship of leg extensors obtained from loaded and unloaded vertical jumps.

Resent research has suggested that loaded multi-joint movements could reveal a linear force-velocity (F-V) relationship. The aim of the present study was to evaluate the F-V relationship both across different types of vertical jumps and across different F and V variables. Ten healthy subjects performed maximum various vertical jumps that were either loaded or unloaded by constant external forces of up to 30 % of their body weight. Both the maximum and averaged F and V data were recorded. The observed F-V relationships proved to be strong (median correlation coefficients ranged 0.78-0.93) and quasi-linear. Their F- and V-intercepts and the calculated maximum power (P) were highly reliable (0.85 < ICC < 0.98), while their concurrent validity with respect to their directly measured values was on average moderate-to-large. The obtained F-V relationships also revealed that (1) the assessment of maximum F and P could be somewhat more reliable and valid than the assessment of maximum V, (2) natural countermovement jumps should be employed rather than the jumps performed from a fixed squat position, while (3) both maximum and averaged F and V variables could be used despite revealing markedly different regression parameters. The data generally reveal a reliable, valid, strong and quasi-linear F-V relationship across variety of vertical jumps and the recorded F and V variables. Therefore, we conclude that the loaded vertical jumps could be developed into a routine method for testing the force, velocity, and power generating capacity of leg extensors.

Emergence and stability of interlimb coordination patterns in children with developmental coordination disorder

The purpose of this study was to investigate the emergence and stability of coordination patterns in children with developmental coordination disorder (DCD) when performing a rhythmic interlimb coordination task on rigid (floor) and elastic (mini-trampoline) surfaces. Twelve typically developing (TD) children and 12 children with DCD were required to clap while jumping under different conditions: in a chosen pattern - Free; when the feet touched the surface - Clapping-surface; when the body reached the maximum jumping height - Clapping-jump; and when the feet touched the surface and the body reached the maximum jumping height - Clapping-both. The results showed that the coordination pattern of children with DCD was more variable in the Free, Clapping-surface, and Clapping-jumping conditions and more variable on the mini-trampoline than on the floor under the Free condition when compared with the TD children. Clapping-jumping was more difficult to perform than Clapping-surface for both groups. These findings suggest that the children with DCD were less capable of rhythmically coordinating the jumping-clapping task because they used a type of exploratory strategy regarding the physical properties of the surfaces, whereas the TD children used a type of adaptive strategy displaying behavior that was more consistent across the tasks/environmental demands.

Body size and countermovement depth confound relationship between muscle power output and jumping performance

A number of studies based on maximum vertical jumps have presumed that the maximum jump height reveals the maximum power of lower limb muscles, as well as the tested muscle power output predicts the jumping performance. The objective of the study was to test the hypothesis that both the body size and countermovement depth confound the relationship between the muscle power output and performance of maximum vertical jumps. Sixty young and physically active males were tested on the maximum countermovement (CMJ) and squat jumps (SJ). The jumping performance (Hmax), peak (Ppeak) and the average power output (Pavg) during the concentric phase, countermovement depth (only in CMJ) and body mass as an index of body size were assessed. To assess the power-performance relationship, the correlations between Hmax with both Ppeak and Pavg were calculated without and with controlling for the effects of body mass, as well as for the countermovement depth. The results revealed moderate power-performance relationships (range .55<r<.64) that were comparable for CMJ and SJ jumps. When controlled for body mass, the same values were markedly higher (.61<r<.82; p<.05 for Ppeak of both jumps). When controlled for both the body mass and countermovement depth, CMJ revealed r=.88 and r=.77 for Ppeak and Pavg, respectively. Both jumps revealed stronger relationships with Ppeak than with Pavg (p<.05) when controlled for either body mass or both body mass and countermovement depth. We conclude that both body size (in CMJ and SJ) and countermovement depth (in CMJ) confound the relationship between the muscle power output with the performance of maximum vertical jumps. Regarding routine assessments of muscle power from jumping performance and vice versa, the use of CMJ is recommended, while Ppeak, rather than Pavg, should be the variable of choice.

Chasing maximal performance: a cautionary tale from the celebrated jumping frogs of Calaveras County

Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs (Rana catesbeiana). We recorded video of 3124 bullfrog jumps over the course of the 4-day contest at the Calaveras County Jumping Frog Jubilee, and determined jump distance from these images and a calibration of the jump arena. Frogs were divided into two groups: 'rental' frogs collected by fair organizers and jumped by the general public, and frogs collected and jumped by experienced, 'professional' teams. A total of 58% of recorded jumps surpassed the maximum jump distance in the literature (1.295 m), and the longest jump was 2.2 m. Compared with rental frogs, professionally jumped frogs jumped farther, and the distribution of jump distances for this group was skewed towards long jumps. Calculated muscular work, historical records and the skewed distribution of jump distances all suggest that the longest jumps represent the true performance limit for this species. Using resampling, we estimated the probability of observing a given jump distance for various sample sizes, showing that large sample sizes are required to detect rare maximal jumps. These results show the importance of sample size, animal motivation and physiological conditions for accurate maximal performance estimates.

Design of an shape memory alloy-actuated biomimetic mobile robot with the jumping gait

This paper reports the design, simulation, analysis, and experiments of mesoscale fourlegged robots that can locomote by a jumping gait using only shape memory alloy (SMA) wires as actuators. Through studies of the structure and function of leg muscle groups in vertebrates’ lower musculoskeletal system, three types of muscles are selected for robot leg design, and each muscle is then replaced by an SMA wire in the robot model. Two types of robot models are proposed and analyzed using three sets of computer simulation. It can be concluded from the simulation that the sequence of SMA muscle activation, activation arrangement of the rear and the front legs, and the foot length are primary factors determining the jumping performance. It is observed that when the robot has three degrees of freedom for each leg and a foot length of 40 mm, the maximum jumping height is approximately 120% of the robot’s height and the maximum distance per jump is about 35% of its length. In addition, two robot prototypes are presented based on the design models and experimental results. The simulation and experimental results are found to show good agreement. The overall results show that the proposed robot design and SMA actuation method are feasible for all SMA-driven jumping robots.

Body mass maximizes power output in human jumping: a strength-independent optimum loading behavior

It is well known that in vitro muscles maximize their power output when acting against a moderate resistance regarding their maximum strength. Similar behavior has been observed from in vivo muscular systems in both single-joint and most of the multi-joint maximum performance tasks. We refer to that phenomenon as a strength-dependent behavior, since the optimum external load that maximizes the mechanical power output of particular muscle(s) or neuro-musculoskeletal system corresponds to a certain percent of maximum strength. In this review paper, we present evidence that the optimum load in maximum vertical jumps is one's own body mass, regardless of the strength of the lower limb muscles (i.e., the strength-independent behavior). Although the discussed phenomenon is still underexplored, we believe that several neuro-mechanical mechanisms are involved. Among these are a long-term adaptation of the muscular force-velocity relationship to the body weight and inertia, alteration of the jumping technique, load-specific muscle activation and jumping skills. Further exploration of the discussed strength-independent behavior of the lower limb muscles is of importance for refining various training and rehabilitation procedures, as well as for understanding the design and function of lower limb muscles.