Take-off Velocity Research Articles

Measurement of the dynamics in ski jumping using a wearable inertial sensor-based system

Dynamics is a central aspect of ski jumping, particularly during take-off and stable flight. Currently, measurement systems able to measure ski jumping dynamics (e.g. 3D cameras, force plates) are complex and only available in few research centres worldwide. This study proposes a method to determine dynamics using a wearable inertial sensor-based system which can be used routinely on any ski jumping hill. The system automatically calculates characteristic dynamic parameters during take-off (position and velocity of the centre of mass perpendicular to the table, force acting on the centre of mass perpendicular to the table and somersault angular velocity) and stable flight (total aerodynamic force). Furthermore, the acceleration of the ski perpendicular to the table was quantified to characterise the skis lift at take-off. The system was tested with two groups of 11 athletes with different jump distances. The force acting on the centre of mass, acceleration of the ski perpendicular to the table, somersault angular velocity and total aerodynamic force were different between groups and correlated with the jump distances. Furthermore, all dynamic parameters were within the range of prior studies based on stationary measurement systems, except for the centre of mass mean force which was slightly lower.

Biomechanical Comparison Between Sprint Start, Sled Pulling, and Selected Squat-Type Exercises

The purpose of this study was to compare kinetics, kinematics, and muscle activity among sprint start, sled pulling, and selected squat-type exercises (countermovement jumps [CMJs] and 1/2-squats with various loads) and also to examine how these exercises correlate with the performance time of the block start (10 m). Nine male athletes (4 sprinters, 3 decathlonists, 1 long jumper, and 1 triple jumper: age = 24.9 ± 3.9 years; 100-m record = 11.35 ± 0.29 seconds; track and field training years = 11.8 ± 3.1 years) volunteered as subjects. The comparisons were made with regard to the block phase (the phase of force production toward starting blocks) of the block start. In nearly all exercises, the activity of the gluteus maximus was significantly (p ≤ 0.05) higher than that during the block phase. Ground reaction forces were larger (p ≤ 0.05) during the 1/2-squats and CMJs. The angular velocity of the knee was significantly (p ≤ 0.05) higher during the CMJs than during the block phase and, in general, the kinematic values of the sled pulling and CMJs were closest to the values of the block start. The highest correlation existed between the performance time in the block start (10 m) and the takeoff velocity during the CMJ without a load (r = -0.950, p ≤ 0.001). In conclusions, the sled pulling and CMJs can be recommended to be used in the training of the block start because both velocity and movement specificity with regard to the block start and, hence, good transfer of training adaptations to the block start can be expected.

Biomechanical Analysis of Standing Long Jump From Varying Starting Positions

The purpose of this study was (a) to investigate the effect of the different foot movement (placement) during take-off and the initial knee joint angle used in standing long jump by the ground reaction forces analysis and 3-dimensional motion analysis (BTS SMART motion) and (b) investigate how the jump performances of different foot placement is related to the electromyography (EMG) activity (Noraxon) of 3 selected muscle groups (m. gastrocnemius, m. gluteus maximus, m. rectus femoris, m. tibialis anterior, m. biceps femoris, and m. vastus medialis). Six high caliber sprinters (100 m: 10.87 ± 0.38 seconds and 400 m: 46.75 ± 1.05 seconds) performed a series of jumps from parallel and straddle foot placement at take-off on a 2 force platform (Kistler model 9286B) to determine if a different pattern of take-off improves jumping distance. Using kinematic and kinetic data, the knee joint angle, the trajectories of center of mass (COM), magnitude of take-off peak force, and impulse during take-off phase were calculated. Average standing long jump performances with straddle foot placement were 13.58 cm (5.18%) above that from parallel feet placement. The take-off velocity with 90° knee initial angle initiation of take-off was not different (1.18 and 1.17 m·s, respectively) between the 2 jumps. The take-off angles on the COM trajectory also showed differences (69.87 and 66.8°, respectively) between each other. The contribution (EMG activation) made by the 6 muscles were almost the same during all phases for the 2 jumps; however, some differences can be found, in either unilateral (single leg) or sums of both legs (bilateral) measurements. A recommendation can be formulated that the contribution of straddle foot placement during take-off can significantly increase the value of power measurement especially when the evaluation requires a complex movement structure with the division on the left and right legs, for example, sprint start from block.

Take-Off Motion Planning of Legged Hopping Robot with Redundancy Characteristic

The planning for four-joint legged hopping robot with two redundant degrees of freedom at the take-off stage is researched. According to the take-off velocity and the boundary condition of centroid motion, the trajectory is planned with variable quartic polynomial interpolation. From inverse kinematics, the motion planning with redundancy characteristic is completed by using the GPM with continuous scale factor. Performance index of avoiding joint limit and optimizing joint driving torque are realized. The data indicates the feasibility and practicability of this algorithm.

Lack of association between postactivation potentiation and subsequent jump performance

Postactivation potentiation (PAP) is a strategy that has been used to acutely enhance the performance of explosive activities. Although, isometric maximal voluntary contractions (MVCs) have previously been shown to enhance subsequent explosive performance, no information currently exists regarding (1) the optimal variables (intensity/volume) of a MVC that best elicits a PAP response, and (2) the utilisation of evoked isometric twitch contractions in combination with performance measures to directly ascertain the presence of PAP following a MVC, and its relationship to performance. Thus, the purpose of this study was to (1) investigate the influence of isometric contraction duration on the PAP response, and (2) to determine the relationship between PAP, indicated as potentiation of muscle twitch force and subsequent jump performance following different-duration MVCs. Eight males (age: 21 ± 0.99) were assessed using performance measures [countermovement jumps] and evoked twitch contractions, before and 4 minutes after three different conditioning contractions (CCs), (1) a 3-second MVC (MVC3), (2) a 5-second MVC (MVC5) and (3) a 7-second MVC (MVC7). Following all CCs, peak twitch torque of the knee extensor muscles was found to increase (MVC3, + 3.9%; MVC5, + 9.6%; MVC7, + 5.2%), although not significantly (P > 0.05). No significant increases in jump height, jump power, rate of force development or takeoff velocity were observed following any of the CCs (P > 0.05). There was also a lack of association between the changes in PAP (twitch torque) and jump height following all CCs (MVC3, r = 0.25; MVC5, r = 0.28; MVC7, r = −0.47). These data indicate that PAP as assessed via twitch contractions is not associated with performance measures subsequent to single-set isometric CCs of varying durations.

The Effects of Temperature and Body Mass on Jump Performance of the Locust Locusta migratoria

Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M 0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M 0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M 1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (L f+t; mm) of the femur and tibia of the hind leg, L f+t = 34.9M 0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight.

Effects of Isometric Scaling on Vertical Jumping Performance

Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli’s law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations.

Neuromuscular differences between boys with and without intellectual disability during squat jump

The purpose of this study was to identify the differences in vertical squat jump (SJ) between volunteers with and without intellectual disability (ID). Thirteen boys with ID (average intelligence quotient, estimated by Wisk III test: 55.6 ± 11.2) and 13 peers without disabilities performed maximal SJ on a force platform. Kinematic data were captured using a six-camera 3D motion analysis system and electromyographic (EMG) activity was recorded using surface electrodes. Unpaired T-test determined the statistical difference between the two groups. The obtained results indicated that the group with ID, jumped lower, developed lower vertical ground reaction forces, knee power output, knee angular velocity, and take-off velocity, and showed longer propulsion duration, decreased mean to maximum agonist EMG activity and higher antagonist/agonist activity ratio. The deficit in the SJ observed in individuals with ID was attributed to a deficit in the examined mechanical and neuromuscular parameters, and especially to the agonist and antagonist co-contraction.

The Validity of the SmartJump Contact Mat

The aim of this study was to establish the criterion validity of the SmartJump contact mat in assessing vertical jump height (VJH) and peak power (PP). Twenty-three participants (15 men, age = 26 ± 6 years; 8 women, age = 26 ± 9 years) completed a maximal effort vertical jump using 3 different jump types (countermovement jump [CMJ], countermovement with arms [CMJA], and squat jump [SJ]). Data were simultaneously collected on both the contact mat and force platform. Vertical jump height was calculated using the time in air (TIA) method with both force platform (TIA(platform)) and contact mat (TIA(mat)) data and the takeoff velocity (TOV) method using the force platform (TOV(platform)) data. Peak power was calculated using a validated equation. The results showed that VJH and PP calculated using the TIA(mat) method were significantly greater than that calculated from the TIA(platform) and TOV(platform) methods for all jump types (VJH: p < 0.001, PP: p < 0.001). The results from this study show clear discrepancies between apparatus and calculation methods that may have implications for practitioners and should be considered when assessing VJH and PP in the field.

Seasonal Changes of Jumping Performance and Knee Muscle Strength in Under-19 Women Volleyball Players

The purpose of the study was to compare the seasonal changes (preparation period [PP] and competition period [CP]) of vertical jumping performance and knee muscle strength in a team of under-19 women volleyball players (N = 12, 16.2 ± 1.5 years). The countermovement jump was used to evaluate jumping performance. The isometric knee extension moment at 150 ms from the onset of contraction (T150) and at a maximum of contraction (TMAX) were determined at 9 knee angles (from 10° to 90°, full knee extension = 0°). The peak isokinetic knee extension (TISOK-EXT) and flexion (TISOK-FLEX) moment were determined at 60, 180, and 240°·s. Repeated-measures analysis of variance was applied to the differences between PP and CP (p ≤ 0.05). Significant increases in jumping performance were found for jump height, peak impulse, total impulse, peak power, and takeoff velocity (p ≤ 0.05). At the knee flexion angles from 40° to 90°, T150 was significantly increased (p ≤ 0.05), whereas the increase was not significant at the rather extended knee angles of 10°, 20°, and 30° (p > 0.05). Only at 90° of knee flexion (p ≤ 0.05), TMAX was significantly increased. With the exception of TISOK-FLEX at 60°·s (p ≤ 0.05), the increases of TISOK-EXT and TISOK-FLEX were not significant (p > 0.05). The TISOK-EXT/TISOK-FLEX ratios were not significantly changed (p > 0.05). The main application of the study is that it provides performance standards and potential criteria for variable selection for jumping performance and knee muscle strength seasonal evaluation.

Enhanced Performance With Elastic Resistance During the Eccentric Phase of a Countermovement Jump

To identify the effect of additional elastic force on the kinetic and kinematic characteristics, as well as the magnitude of leg stiffness, during the performance of accentuated countermovement jumps (CMJs). Fifteen trained male subjects performed 3 types of CMJ including free CMJ (FCMJ; ie, body weight), ACMJ-20, and ACMJ-30 (ie, accentuated eccentric CMJ with downward tensile force equivalent to 20% and 30% body mass, respectively). A force platform synchronized with 6 high-speed infrared cameras was used to measure vertical ground-reaction force (VGRF) and displacement. Using downward tensile force during the lowering phase of a CMJ and releasing the bands at the start of the concentric phase increased maximal concentric VGRF (6.34%), power output (23.21%), net impulse (16.65%), and jump height (9.52%) in ACMJ-30 compared with FCMJ (all P < .05). However, no significant difference was observed in the magnitude of leg stiffness between the 3 modes of jump. The results indicate that using downward recoil force of the elastic material during the eccentric phase of a CMJ could be an effective method to enhance jump performance by applying a greater eccentric loading on the parallel and series elastic components coupled with the release of stored elastic energy. The importance of this finding is related to the proposition that power output, net impulse, takeoff velocity, and jump height are the key parameters for successful athletic performance, and any training method that improves impulse and power production may improve sports performance, particularly in jumping aspects of sport.

Trade-offs between horizontal and vertical velocities during triple jumping and the effect on phase distances

The triple jump is an athletic event involving three ground contact phases during which athletes must trade off the maintenance of horizontal velocity against the generation of vertical velocity. Previous studies have indicated that individual athletes have a linear relationship between the loss in horizontal velocity and the gain in vertical velocity during each phase. This study used computer simulation to investigate the effects of constraining the takeoff velocities in the hop phase on the velocity trade-offs in this and subsequent phases. Kinematic data were obtained from an entire triple jump using a Vicon automatic motion capture system, and strength and anthropometric data were collected from the triple jumper. A planar 13-segment torque-driven subject-specific computer simulation model was used to maximise the distance of each phase by varying torque generator activation timings using a genetic algorithm. Vertical takeoff velocities in the hop phase were constrained to be 100%, ±10%, ±20%, and ±30% of the performance velocity, and subsequent phases were optimised with initial conditions calculated from the takeoff of the previous phase and with no constraints on takeoff velocity. The results showed that the loss in horizontal velocity during each contact phase was strongly related to the vertical takeoff velocity (R2=0.83) in that phase rather than the overall gain in vertical velocity as found in previous studies. Maximum overall distances were achieved with step phases which were 30% of the total distance of the triple jump confirming the results of experimental studies on elite triple jumpers.

Jumping from the surface of water by the long-legged flyHydrophorus(Diptera, Dolichopodidae)

The fly Hydrophorus alboflorens (4 mm long, 4.7 mg mass) moves around upon and jumps from water without its tarsi penetrating the surface. All six tarsi have a surface area of 1.3 mm(-2) in contact with the water, but they did not dimple its surface when standing. Jumping was propelled by depression of the trochantera of both hind and middle legs, which are 40% longer than the front legs and 170% longer than the body. As these four legs progressively propelled the insect to take-off, they each created dimples on the water surface that expanded in depth and area. No dimples were associated with the front legs, which were not moved in a consistent sequence. The wings opened while the legs were moving and then flapped at a frequency of 148 Hz. The body was accelerated in a mean time of 21 ms to a mean take-off velocity of 0.7 m s(-1). The best jumps reached velocities of 1.6 m s(-1), and required an energy output of 7 μJ and a power output of 0.6 mW, with the fly experiencing a force of 140 g. The required power output indicates that direct muscle contractions could propel the jump without the need for elaborate mechanisms for energy storage. Take-off trajectories were steep, with a mean of 87 deg to the horizontal. Take-off velocity fell if a propulsive tarsus penetrated the surface of the water. If more tarsi became submerged, take-off was not successful. A second strategy for take-off was powered only by the wings and was associated with slower (1 deg ms(-1) compared with 10 deg ms(-1) when jumping) and less extensive movements of the propulsive joints of the middle and hind legs. No dimples were then created on the surface of the water. When jumping was combined with wing flapping, the acceleration time to take-off was reduced by 84% and the take-off velocity was increased by 168%. Jumping can potentially therefore enhance survival when threatened by a potential predator.

Jumping mechanisms in dictyopharid planthoppers (Hemiptera, Dicytyopharidae)

The jumping performance of four species of hemipterans belonging to the family Dictyopharidae, from Europe, South Africa and Australia, were analysed from high-speed images. The body shape in all was characterised by an elongated and tapering head that gave a streamlined appearance. The body size ranged from 6 to 9 mm in length and from 6 to 23 mg in mass. The hind legs were 80-90% of body length and 30-50% longer than the front legs, except in one species in which the front legs were particularly large so that all legs were of similar length. Jumping was propelled by rapid and simultaneous depression of the trochantera of both hind legs, powered by large muscles in the thorax, and was accompanied by extension of the tibiae. In the best jumps, defined as those with the fastest take-off velocity, Engela minuta accelerated in 1.2 ms to a take-off velocity of 5.8 m s(-1), which is the fastest achieved by any insect described to date. During such a jump, E. minuta experienced an acceleration of 4830 m s(-2) or 490 g, while other species in the same family experienced 225-375 g. The best jumps in all species required an energy expenditure of 76-225 μJ, a power output of 12-80 mW and exerted a force of 12-29 mN. The required power output per mass of jumping muscle ranged from 28,000 to 140,200 W kg(-1) muscle and thus greatly exceeded the maximum active contractile limit of normal muscle. To achieve such a jumping performance, these insects must be using a power amplification mechanism in a catapult-like action. It is suggested that their streamlined body shape improves jumping performance by reducing drag, which, for a small insect, can substantially affect forward momentum.

Jumping mechanisms in gum treehopper insects (Hemiptera, Eurymelinae)

Jumping in a species of Australian gum treehopper was analysed from high-speed images. Pauroeurymela amplicincta adults and nymphs lived together in groups that were tended by ants, but only adults jumped. The winged adults with a body mass of 23 mg and a body length of 7 mm had some morphological characteristics intermediate between those of their close relatives the leafhoppers (Cicadellidae) and the treehoppers (Membracidae). They, like leafhoppers, lacked the prominent prothoracic helmets of membracid treehoppers, and their large hind coxae were linked by press studs (poppers), that are present in leafhoppers but not treehoppers. The hindlegs were only 30-40% longer than the other legs and 67% of body length. They are thus of similar proportion to the hindlegs of treehoppers but much shorter than those of most leafhoppers. Jumping was propelled by the hindlegs, which moved in the same plane as each other beneath and almost parallel to the longitudinal axis of the body. A jump was preceded by full levation of the coxo-trochanteral joints of the hindlegs. In its best jumps, the rapid depression of these joints then accelerated the insect in 1.4 ms to a take-off velocity of 3.8 m s(-1) so that it experienced a force of almost 280 g. In 22% of jumps, the wings opened before take-off but did not flap until the gum treehopper was airborne, when the body rotated little in any plane. The energy expended was 170 μJ, the power output was 122 mW and the force exerted was 64 mN. Such jumps are predicted to propel the insect forwards 1450 mm (200 times body length) and to a height of 430 mm if there is no effect of wind resistance. The power output per mass of jumping muscle far exceeded the maximum active contractile limit of muscle and indicates that a catapult-like action must be used. This eurymelid therefore out-performs both leafhoppers and treehoppers in i ts faster acceleration and in its higher take-off velocity.

Biomechanical analysis of the final strides of the approach and the take-off by visually impaired class F12 and F13 long jumpers

Despite of the level of visual aquity, European Records in long jumping are greater in class F12 (visual acuity 2/60) than class F13 (visual acuity 6/60) both in males and females. The aim of the present study was to compare the biomechanical parameters of the final strides of the approach and the take-off in class F12 and F13 long jumpers. 19 class F12 (males: 13, females: 6) and 12 class F13 (males: 4, females: 8) long jumpers participating in the 2009 International Blind Sports Association European Championships were recorded using a stationary digital video camera (sampling frequency: 300 fps). Key biomechanical parameters were extracted with a typical 2D-DLT kinematical analysis. Differences between groups were investigated using Independent samples t-test. Results indicated that the official distance was 6.07 m ± 0.55 and 5.52 m ± 0.91 for F12 and F13 respectively (p<.05). Significant differences were also observed concerning the vertical take-off velocity (F12: 2.8 m/sec, F13: 2.4 m/sec), the support leg's knee flexion (F12: 18.2 deg, F13: 25.2 deg) and the knee joint flexion velocity (F12: 7.4 rad/sec, F13: 10.2 rad/sec) at the take-off board and the knee maximum flexion angle at the last stride (F12: 116.8 deg, F13: 125.4 deg). In conclusion, F12 performed better than F13 because of the more advantageus utilization of the factors defining the vertical component in the long- jump take-off. Additionally, the different last stride maximum knee flexion angle might imply differences concerning the mechanics of the placement of the take-off leg. It is possible that factors such as the size and surface properties of the 1.22 m x 1.00 m chalked take-off area used in F12 competition may contribute to the differences observed in the study.

Influence of Rest Intervals After Assisted Jumping on Bodyweight Vertical Jump Performance

Assisted jumping (an overspeed concept) is a method used to improve vertical jump performance. However, research is lacking on the optimal program design to maximize performance outcomes. The purpose of this study was to determine the influence of rest intervals after assisted jumping on bodyweight (BW) vertical jumps. Twenty healthy recreationally trained men (age: 22.85 ± 1.84 years; height: 179.44 ± 5.99 cm; mass: 81.73 ± 9.51 kg) attended 5 sessions. For all sessions, subjects performed the same dynamic warm-up and then executed 1 set of 5 consecutive assisted jumps at 30% BW reduction. They then rested for 30 seconds (C30), 1 minute (C1), 2 minutes (C2), or 4 minutes (C4), followed by 3 BW jumps with no assistance. Baseline (CB) jump height was measured without preceding assisted jumps. Analyses of variance revealed a main effect for takeoff velocity, with 1 and 4 minutes being greater than baseline (C1: 3.36 ± 0.40 m·s(-1); C4: 3.27 ± 0.41 m·s(-1); CB: 3.13 ± 0.32 m·s(-1)). Relative peak power also demonstrated a main effect, with 1 minute being greater than all other conditions (C1: 75.22 ± 10.83 W·kg(-1)). Jump height and relative ground reaction force demonstrated no differences between conditions. These results indicate overspeed jumping acutely enhances explosive BW jumping velocity and power. This acute performance enhancement is probably a result of increased motor neuron excitability and motor unit synchronization.

Biodynamic characteristics of vertical and drop jumps

The aim of the study was to establish the main kinematic and dynamic parameters that generate the efficiency of vertical and drop jumps. The take-off power was assessed using the following tests: countermovement jump, counter-movement jump with arm swing, jump, drop jump and continuous jump. Kinematic and dynamic parameters of vertical and drop jumps were established using two separate forceplates Kistler Type 9286A and a synchronised 3-D kinematic system CCD SMART-600E. The athlete model was defined with 17 markers sensitive to infra-red light. It was established that the main generators of efficiency in vertical and drop jumps included: take-off velocity, eccentric-concentric time, eccentric impulse, ground contact time and ankle flexion.

The categorisation of swimming start performance with reference to force generation on the main block and footrest components of the Omega OSB11 start blocks

Work presented in this paper provides a methodology for categorising swimming start performance based on peak force production on the main block and footrest components of the Omega OSB11 starting block. A total of 46 elite British swimmers were tested, producing over 1000 start trials. Overwater cameras were synchronised to a specifically designed start block that allowed the measurement of force production via two sets of four, tri-axis, force transducers; one set in the main block and one in the footrest. Data were then analysed, segregating trials for gender. Each start was categorised, with respect to the peak force production in horizontal and vertical components, into one of nine categories. Three performance indicators, i.e. block time, take-off velocity and distance of entry, were used to assess whether differences in performance could be correlated with these categories. Results from these data suggest that swimmers generating higher than average peak forces were more likely to produce a better overall start performance than those who produced forces lower than the average, for this population of athletes.

Surface roughness, claw size and leg elasticity influences on the jumping of Acheta domesticus crickets

The jumping of living house crickets (Acheta domesticus) on three sandpapers with different roughness and the mechanical properties of their legs have been studied. The longest jumps are observed when the higher friction occurs, that in turn happens when the average particle diameter of each substratum is comparable to the insect’s claw diameter. In the longest jump, the cricket A. domesticus was propelled forwards for almost 30cm, about 16 times its body length, to a take-off velocity of 1.8m/s at an angle of 36.9° with a kinetic energy of 520μJ, in agreement with previously published studies where the role of friction was not elucidated. In addition, the crickets’ legs were also strained at the constant rate of 1mm/min, using a tensile testing machine. The observed maximum stress, strain and toughness modulus, defined as the area under the stress–strain curve, are 69.4MPa, 17.4% and 0.72MJ/m3, respectively, and are compatible with the required jumping performances. Finally, we compare the jumping performances of A. domesticus with other jumping insects, such as locusts, planthoppers, froghoppers, bush crickets, pygmy mole crickets, false stick insects and stick insects, which were analysed in previously published papers.