Jumping kinematics in the wandering spider Cupiennius salei

Spiders use hemolymph pressure to extend their legs. This mechanism should be challenged when required to rapidly generate forces during jumping, particularly in large spiders. However, effective use of leg muscles could facilitate rapid jumping. To quantify the contributions of different legs and leg joints, we investigated jumping kinematics by high-speed video recording. We observed two different types of jumps following a disturbance: prepared and unprepared jumps. In unprepared jumps, the animals could jump in any direction away from the disturbance. The remarkable directional flexibility was achieved by flexing the legs on the leading side and extending them on the trailing side. This behaviour is only possible for approximately radial-symmetric leg postures, where each leg can fulfil similar functions. In prepared jumps, the spiders showed characteristic leg positioning and the jumps were directed anteriorly. Immediately after a preliminary countermovement in which the centre of mass was moved backwards and downwards, the jump was executed by extending first the fourth and then the second leg pair. This sequence provided effective acceleration to the centre of mass. At least in the fourth legs, the hydraulic and the muscular mechanism seem to interact to generate ground reaction forces.     

A cockroach that jumps

We report on a newly discovered cockroach (Saltoblattella montistabularis) from South Africa, which jumps and therefore differs from all other extant cockroaches that have a scuttling locomotion. In its natural shrubland habitat, jumping and hopping accounted for 71 per cent of locomotory activity. Jumps are powered by rapid and synchronous extension of the hind legs that are twice the length of the other legs and make up 10 per cent of the body weight. In high-speed images of the best jumps the body was accelerated in 10 ms to a take-off velocity of 2.1 m s(-1) so that the cockroach experienced the equivalent of 23 times gravity while leaping a forward distance of 48 times its body length. Such jumps required 38 μJ of energy, a power output of 3.4 mW and exerted a ground reaction force through both hind legs of 4 mN. The large hind legs have grooved femora into which the tibiae engage fully in advance of a jump, and have resilin, an elastic protein, at the femoro-tibial joint. The extensor tibiae muscles contracted for 224 ms before the hind legs moved, indicating that energy must be stored and then released suddenly in a catapult action to propel a jump. Overall, the jumping mechanisms and anatomical features show remarkable convergence with those of grasshoppers with whom they share their habitat and which they rival in jumping performance.     

The jump of the click beetle (Coleoptera, Elateridae)—a preliminary study

A preliminary account is given of the jump of the click beetle, Athous haemorrhoidalis (F.). The jump is normally made from an inverted position. It involves a jack-knifing movement whereby a prosternal peg is slid very rapidly down a smooth track into a mesosternal pit. The muscles which produce this movement are allowed to build up tension by a friction hold on the dorsal side of the peg. The anatomy of this jumping mechanism is briefly described. Ciné recording showed that the jump was usually nearly vertical and could exceed 0.3m in height; the beetle normally rotated several times head over tail during a jump. The jump was produced by a very rapid upwards movement of the beetle's centre of gravity during the jack-knifing action. In a typical jump, a 4 × 10⁻⁵ kg beetle could be subjected to an upwards acceleration of 3800 m/s⁻² (380 g). The minimum work done and the power output of the muscles causing jumping have been calculated. A simple mechanical model has been constructed to simulate a jump, and several possible ways in which the jumping mechanism could operate have been discussed.     

Design and Demonstration of a Locust-Like Jumping Mechanism for Small-Scale Robots

A jumping mechanism can be an efficient mode of motion for small robots to overcome large obstacles on the ground and rough terrain.In this paper,we present a 7 g prototype of locust-inspired jumping mechanism that uses springs,wire,reduction gears,and a motor as the actuation components.The leg structure and muscles of a locust or grasshopper were mimicked using springs and wire,springs for passive extensor muscles,and a wire as a flexor muscle.A small motor was used to slowly charge the spring through a lever and gear system,and a cam with a special profile was used as a clicking mechanism for quick release of elastic energy stored in the springs to create a sudden kick for a quick jump.Performance analysis and experiments were conducted for comparison and performance estimation of the jumping mechanism prototype.Our prototype could produce standing jumps over obstacles that were about 14 times its own size (approximate to 71 cm) and a jumping distance of 20 times its own size (approximate to 100 cm).     

Motor activity and trajectory control during escape jumping in the locust <Emphasis Type="Italic">Locusta migratoria</Emphasis>

We investigated the escape jumps that locusts produce in response to approaching objects. Hindleg muscular activity during an escape jump is similar to that during a defensive kick. Locusts can direct their escape jumps up to 50° either side of the direction of their long axis at the time of hindleg flexion, allowing them to consistently jump away from the side towards which an object is approaching. Variation in jump trajectory is achieved by rolling and yawing movements of the body that are controlled by the fore- and mesothoracic legs. During hindleg flexion, a locust flexes the foreleg ipsilateral to its eventual jump trajectory and then extends the contralateral foreleg. These foreleg movements continue throughout co-contraction of the hindleg tibial muscles, pivoting the locust’s long axis towards its eventual jump trajectory. However, there are no bilateral differences in the motor programs of the left and right hindlegs that correlate with jump trajectory. Foreleg movements enable a locust to control its jump trajectory independent of the hindleg motor program, allowing a decision on jump trajectory to be made after the hindlegs have been cocked in preparation for a jump.     

Explanation of the bilateral deficit in human vertical squat jumping.

In the literature, it has been reported that the mechanical output per leg is less in two-leg jumps than in one-leg jumps. This so-called bilateral deficit has been attributed to a reduced neural drive to muscles in two-leg jumps. The purpose of the present study was to investigate the possible contribution of nonneural factors to the bilateral deficit in jumping. We collected kinematics, ground reaction forces, and electromyograms of eight human subjects performing two-leg and one-leg (right leg) squat jumps and calculated mechanical output per leg. We also used a model of the human musculoskeletal system to simulate two-leg and one-leg jumps, starting from the initial position observed in the subjects. The model had muscle stimulation as input, which was optimized using jump height as performance criterion. The model did not incorporate a reduced maximal neural drive in the two-leg jump. Both in the subjects and in the model, the work of the right leg was more than 20% less in the two-leg jump than in the one-leg jump. Peak electromyogram levels in the two-leg jump were reduced on average by 5%, but the reduction was only statistically significant in m. rectus femoris. In the model, approximately 75% of the bilateral deficit in work per leg was explained by higher shortening velocities in the two-leg jump, and the remainder was explained by lower active state of muscles. It was concluded that the bilateral deficit in jumping is primarily caused by the force-velocity relationship rather than by a reduction of neural drive.     

The jump as a fast mode of locomotion in arboreal and terrestrial biotopes

The jump is always used for locomotion. For its execution in arboreal and terrestrial biotopes the requirements are of somewhat different nature. In an arboreal biotope the jump is characterized by a rapid progression through discontinuous substrates and the ability to take off from a small area and a secure landing on a spot. This requires well coordinated movements in all phases of the jump. On the ground, the jump is less frequent and often used for crossing obstacles or gaps. In primates both variants can be observed. In order to relate the details of locomotor behaviour to a certain environment, the biomechanics of jumping are analyzed in five primate species: The three mainly arboreal prosimian species Galago moholi, the smallest and most specialized leaper of all, Galago garnettii, a medium-sized bushbaby with some capacities for jumping, and Lemur catta also with some abilities to jump. The two simian species, Macaca fuscata and Homo sapiens, are usually terrestrial and have good jumping capacities, although not in terms of quantity. The investigation is based on high-speed motion analyses (100-500 frames/second) and the synchronized records of a force-plate from which all subjects had to jump off. On the basis of the results two kinds of jumping can be distinguished: standing and running jumps. The three prosimian species perform standing jumps. Dorsiflexion of their tails compensates ventrally oriented rotational moments of the trunk during body extension at take-off. The upward arm swing yields an overall increase in take-off velocity without additional muscular force exerted by the legs. The main difference among the species are the high relative forces in the small Galago moholi (up to 13 times body weight) as compared to the larger G. garnettii (8.5 times body weight) and the even larger Lemur catta (4.5 times body weight). In Homo sapiens the standing jump is characterized by an extensive arm swing backward, which is then followed by a forward and upward movement. The velocity at take-off is much smaller if compared to the prosimians. The running jump in Macaca fuscata is always preceded by at least one gallop cycle. The body assumes a ball shape at the beginning of the actual take-off. This is advantageous for rotating the body into a position in which the trunk axis is in line with the direction of movement. The tail of the Japanese macaque is too short to compensate the trunk's lift exerted on the hip region by the extending hindlimbs.(ABSTRACT TRUNCATED AT 400 WORDS)     

Gender bias in the effects of arms and countermovement on jumping performance

The ability to jump high is considered important in a number of sports. It is commonly accepted that the use of the arms and a counter movement increase jump height. In some sport situations (e.g., volley ball block, basketball rebound), athletes may not be able to utilize a counter movement or arm swing. The purpose of this study is to examine gender differences in the contribution of the arm swing and counter movement to vertical jump height. Fifty college students, 25 men (age = 21.4 +/- 1.7 years, height = 182.2 +/- 8 cm, weight = 83.7 +/- 12.4 kg) and 25 women (age = 20.7 +/- 1.6 years, height = 166.7 +/- 6.3 cm, weight = 61.5 +/- 7.0 kg), performed 4 jumping movements: squat jumps with hands on hips (SNA), counter movement jump with hands on hips (CMNA), squat jump with arm swing (SA), and counter movement with arm swing (CMA). Significant differences were found between men's and women's performance, as well as between each type of jump within each gender. A mixed-model analysis of variance detected gender differences with respect to changes in the jumping movement. For both sexes the jumps in order from worst to best were SNA, CMNA, SA, and CMA. Peak power values for men were 4,057, 4,020, 4,644, and 4,747 W, respectively, for the 4 jumps. The female power values were 2,543, 2,445, 2,842, and 2,788 W, respectively, for the 4 jumps. Arms increased jump height more than a counter movement for both genders, with jump heights for men at 29.6, 31, 36, and 38 cm, respectively, and those of women 21, 22, 26, and 27 cm, respectively. Use of the arms was found to increase the jump height of the men significantly more than that of women. Changes in jumping movements affect men and women differently. The greater increase in jump height for the men when using the arm swing could be because of greater upper body strength of men compared with women. This could have applications to training and upper body strength and also to modeling of jumping movements.     

Surface electromyographic assessment of the effect of static stretching of the gastrocnemius on vertical jump performance

The purpose of this study was to investigate the effects of static stretching of the gastrocnemius muscle on maximal vertical jump performance using electromyographic activity (EMG) of the gastrocnemius musculature to record muscle activation during vertical jump performance. Fourteen healthy adults (8 men and 6 women) aged 18-34 years, who were familiar with the vertical jumping task and had no lower extremity injuries or any bone or joint disorders within the past year, served as participants for this study. After a brief warm-up, participants performed the following sequence: (a) three baseline maximal vertical jump trials, (b) 15 minutes of quiet sitting and three 30-second bilateral static stretches of the gastrocnemius muscles, and (c) 3 maximal vertical jump trials. Jump height data were collected using the Kistler force plate, while muscle activity was recorded during the jumping and stretching trials using a Noraxon telemetry EMG unit. Vertical jump height data as well as EMG values were averaged for the 3 trials and analyzed using paired t-tests for pre- and poststretching (alpha = 0.05). Vertical jump height was 5.6% lower when poststretch heights were compared with prestretch heights (t = -4.930, p < 0.005). Gastrocnemius EMG was 17.9% greater when the EMG during poststretch jumps was compared with prestretch jumps (t = 2.805, p < 0.02). The results from this study imply that, despite increased gastrocnemius muscle activity, static stretching of the gastrocnemius muscles had a negative effect on maximal jumping performance. The practical importance concerns coaches and athletes, who may want to consider the potential adverse effects of performing static stretching of the gastrocnemius muscles only before a jumping event, as jump height may be negatively affected. Future research is required to identify the mechanisms that affect vertical jump performance.     

Muscle dynamics differences between legs in healthy adults

Differences in muscle dynamics between the preferred and nonpreferred jumping legs of subjects in maximal, explosive exercise were examined. Eight subjects performed nonfatiguing bouts of single-legged drop jumps and rebound jumps on a force sledge apparatus. Measures of flight time, reactive strength index, peak vertical force, and vertical leg-spring stiffness were obtained for 3 drop jumps and 3 rebound jumps on both legs. Subjects utilized a stiffer leg spring and a more explosive jumping action in the nonpreferred leg when performing a cyclical rebound jumping task in comparison to a single drop jump task (observed through differences in vertical leg-spring stiffness, peak vertical force, and reactive strength index, p < 0.05). The preferred leg performed equally well in both tasks. Between-leg analysis showed no differences in dependent variables between the preferred and the nonpreferred leg in the rebound jumping protocol. However, the drop jump protocol showed significant performance differences, with flight time and reactive strength index greater in the preferred leg than the nonpreferred leg (p < 0.05). We hypothesize that, throughout the lifespan, both legs are equally trained in cyclical rebound jumping tasks through running. However, because a preferred leg must be selected when performing any one-off, single-legged jump, imbalances in this specific task develop over time with consistent selection of a preferred jumping leg. The data demonstrate that the rebound jump protocol is representative of the symmetrical mechanics of forward running and that leg-spring stiffness is modulated depending on the demands of the specific task involved. Strength and conditioning practitioners should give careful consideration to appropriate jump protocol selection and should exercise caution when comparing laboratory results to data gathered in field testing.     

Fast actions in small animals: springs and click mechanisms

Small animals that jump or perform predatory strikes depend on much higher limb accelerations than larger animals. To overcome the temporal restrictions of muscle contraction, some arthropod muscles slowly load spring-like structures with potential energy. In flight, sound generation, jumping, or predatory strikes arthropods employ different strategies to transform muscular action to the desired movement. Click mechanisms control the frequency of oscillating spring — muscle systems while other accessory structures such as snap mechanism or latches with trigger mucles determined the stability and control the timing of the instantaneous discharge in catapult mechanisms.     

Movement control strategies during jumping in a lizard (Anolis valencienni)

Whereas maximal performance is subjected to specific control criteria, sub-maximal movements theoretically allow for an infinite number of control strategies. Yet sub-maximal movements are predominant in the locomotor repertoire of most organisms and often little understood. Previous data on sub-maximal vertical jumping in humans has suggested that a movement effectiveness criterion might best explain the observed control strategy employed. Here we test the generality of this criterion in jumping by inducing lizards to jump both at a range of distances as well as a range of take-off angles. Our results show that while movement effectiveness appears to best explain jumping for different take-off angles, a 'push harder' strategy (i.e. mostly increasing the force output of the system), is used in the control of distance jumping. Thus, our data support the generality of the movement effectiveness criterion for vertical jumping, but not for distance jumping. Sub-maximal distance jumping in the lizard Anolis valencienni appears to be governed by a relatively simple control strategy that allows a rapid response. This accords well to the ecological circumstances in which long jumps are typically used (escape from predators).     

Gender bias in jumping kinetics in National Collegiate Athletic Association Division I basketball players

The purposes of this study are to examine gender differences in the contribution of the arm swing to jump height in men and women basketball players and to examine the role of upper-body strength in the contribution of arm swing to jump height. National Collegiate Athletic Association Division I basketball players (men n = 13, women n = 12) performed 4 jumping movements: squat jumps with hands on hips (SNA) and with arm swings (SA) and countermovement jumps with hands on hips and with arm swings (CMA). Differences were found between the jump heights of men and women. Use of the arms increased the jump height of men more than women. Compared with the SNA, the SA allowed an increase of 7 cm (23%) for men and 4 cm (17%) for women. The CMA allowed for an increase of 10 cm (30%) for men and 6 cm (24%) for women. General upper-body strength measures did not correlate strongly with the effect of arms on jumping, but peak power did. As in previous studies, peak power had a high correlation with jumping performance. These results show that the arm swing contributes significantly to jump performance in both men and women basketball players and that strength training for jumping should focus on power production and lifting exercises that are jump specific.     

Reliability of leg muscle electromyography in vertical jumping

In this study we aimed to determine the reliability of the surface electromyography (EMG) of leg muscles during vertical jumping between two test sessions, held 2 weeks apart. Fifteen females performed three maximal vertical jumps with countermovement. The displacement of the body centre of mass (BCM), duration of propulsion phase (time), range of motion (ROM) and angular velocity of the knee and surface EMG of four leg muscles (rectus femoris, vastus medialis. biceps femoris and gastrocnemius) were recorded during the jumps. All variables were analysed throughout the propulsion and mid-propulsion phases. Intraclass correlation coefficients (ICC) for the rectus femoris, vastus medialis, biceps femoris and gastrocnemius were calculated to be 0.88, 0.70, 0.24 and 0.01, respectively. BCM, ROM and time values all indicated ICC values greater than 0.90, and the mean knee angular velocity was slightly lower, at 0.75. ICCs between displacement of the BCM and integrated EMG (IEMG) of the muscles studied were less than 0.50. The angular velocity of the knee did not correlate well with muscle activity. Factors that may have affected reliability were variations in the position of electrode replacement, skin resistance, cross-talk between muscles and jump mechanics. The results of this study suggest that while kinematic variables are reproducible over successive vertical jumps, the degree of repeatability of an IEMG signal is dependent upon the muscle studied.     

The effect of dropping height on jumping performance in trained and untrained prepubertal boys and girls

Plyometric training in children, including different types of jumps, has become common practice during the last few years in different sports, although there is limited information about the adaptability of children with respect to different loads and the differences in performance between various jump types. The purpose of this study was to examine the effect of gender and training background on the optimal drop jump height of 9- to 11-year-old children. Sixty prepubertal (untrained and track and field athletes, boys and girls, equally distributed in each group [n = 15]), performed the following in random order: 3 squat jumps, 3 countermovement jumps (CMJs) and 3 drop jumps from heights of 10, 20, 30, 40, and 50 cm. The trial with the best performance in jump height of each test was used for further analysis. The jump type significantly affected the jump height. The jump height during the CMJ was the highest among all other jump types, resulting in advanced performance for both trained and untrained prepubertal boys and girls. However, increasing the dropping height did not change the jumping height or contact time during the drop jump. This possibly indicates an inability of prepubertal children to use their stored elastic energy to increase jumping height during drop jumps, irrespective of their gender or training status. This indicates that children, independent of gender and training status, have no performance gain during drop jumps from heights up to 50 cm, and therefore, it is recommended that only low drop jump heights be included in plyometric training to limit the probability of sustaining injuries.     

Effect of arm motion on standing lateral jumps

The role of arm swing in jumping has been examined in numerous studies of standing jumps for height and forward distance, but no prior studies have explored its effect on lateral jumping. The purpose of the present study was to investigate the effect of arm motion on standing lateral jump performance and to examine the biomechanical mechanisms that may explain differences in jump distance. Six participants executed a series of jumps for maximum lateral distance from two in-ground force platforms for two jump cases (free and restricted arms) while an eight-camera, passive-reflector, motion capture system collected 3D position data throughout the movements. Inverse kinematics and dynamics analyses were performed for all jumps using three-dimensional (3D) link models to calculate segment angular velocities, joint moments, joint powers, and joint work. Free arm motion improved standing lateral jump performance by 29% on average. This improvement was due to increased takeoff velocity and improved lateral and vertical positions of the center of gravity (CG) at takeoff and touchdown. Improved velocity and position of the CG at takeoff resulted from a 33% increase in the work done by the body. This increase in work in free arm jumps compared to restricted arm jumps was found in both upper and lower body joints with the largest improvements (>30 J) occurring at the lower back, right hip, and right shoulder.     

Is energy expenditure taken into account in human sub-maximal jumping? – A simulation study

This paper presents a simulation study that was conducted to investigate whether the stereotyped motion pattern observed in human sub-maximal jumping can be interpreted from the perspective of energy expenditure. Human sub-maximal vertical countermovement jumps were compared to jumps simulated with a forward dynamic musculo-skeletal model. This model consisted of four interconnected rigid segments, actuated by six Hill-type muscle actuators. The only independent input of the model was the stimulation of muscles as a function of time. This input was optimized using an objective function, in which targeting a specific sub-maximal height value was combined with minimizing the amount of muscle work produced. The characteristic changes in motion pattern observed in humans jumping to different target heights were reproduced by the model. As the target height was lowered, two major changes occurred in the motion pattern. First, the countermovement amplitude was reduced; this helped to save energy because of reduced dissipation and regeneration of energy in the contractile elements. Second, the contribution of rotation of the heavy proximal segments of the lower limbs to the vertical velocity of the centre of gravity at take-off was less; this helped to save energy because of reduced ineffective rotational energies at take-off. The simulations also revealed that, with the observed movement adaptations, muscle work was reduced through improved relative use of the muscle's elastic properties in sub-maximal jumping. According to the results of the simulations, the stereotyped motion pattern observed in sub-maximal jumping is consistent with the idea that in sub-maximal jumping, subjects are trying to achieve the targeted jump height with minimal energy expenditure.     

Effects of electromyostimulation training and volleyball practice on jumping ability

The aim of this study was to investigate the influence of a 4-week electromyostimulation (EMS) training program on the vertical jump performance of 12 volleyball players. EMS sessions were incorporated into volleyball sessions 3 times weekly. EMS consisted of 20-22 concomitant stimulations of the knee extensor and plantar flexor muscles and lasted approximately 12 minutes. No significant changes were observed after EMS training for squat jump (SJ) and counter movement jump (CMJ) performance, while the mean height and the mean power maintained during 15 seconds of consecutive CMJs significantly increased by approximately 4% (p < 0.05). Ten days after the end of EMS training, the jumping height significantly (p < 0.05) increased compared with baseline also for single jumps (SJ +6.5%, CMJ +5.4%). When the aim of EMS resistance training is to enhance vertical jump ability, sport-specific workouts following EMS would enable the central nervous system to optimize the control to neuromuscular properties.     

The jumping mechanism of cicada Cercopis vulnerata (Auchenorrhyncha, Cercopidae): skeleton-muscle organisation, frictional surfaces, and inverse-kinematic model of leg movements

In Auchenorrhyncha, jumping is achieved by metathoracic muscles which are inserted into the trochanter of the hind leg. The synchronisation of movements of the hind legs is a difficult problem, as the leg extension that produces the jump occurs in less than 1 ms. Even slight asynchrony could potentially result in failure of a jump. Both the synchronisation of the movements of a pair of jumping legs, and their stabilisation during a jump, seem to be important problems for small jumping insects. The present study was performed in order to clarify some questions of the functional morphology of the leafhopper jumping mechanism. It is based on skeleton-muscle reconstruction, high-speed video recordings, transmission (TEM) and scanning electron microscopic (SEM) investigations of the cuticle, together with 3D inverse-kinematic modelling of angles and working zones of hind leg joints of cicada Cercopis vulnerata (Cercopidae). The complete extension of the hind leg takes less than 1 ms, which suggests that the jump is powered not only by the muscle system, but also by an elastic spring. Histological staining and fluorescence microscopy showed resilin-bearing structures, responsible for elastic energy storage, in the pleural area of the metathorax. Synchronisation of hind leg movements may be aided by microtrichia fields that are located on the medial surface of each hind coxa. In Auchenorrhyncha, hind coxae are rounded in their anterior and lateral parts, whereas medial parts are planar, and contact each other over a rather large area. The inverse-kinematic model of propulsive leg movements was used to draw the surface outlined by the medial surface of the coxa, during the jump movement. This is a cone surface, faced with its bulged-in side, medially. Surfaces outlined by the movements of both right and left coxae overlap in their anterior and posterior positions. In both extreme positions, coxae are presumably connected to each other by coupled microtrichia fields. Thus, in extreme positions, both coxae can be moved synchronously.