To establish the influence of athlete-dependent characteristics on the generation and timing of system and individual joint powers during a countermovement jump (CMJ).
Male national representative ...athletes from volleyball (n = 7), basketball (n = 6), and rugby (n = 7) performed a set of 3 CMJs at relative barbell loads of 0%, 10%, 20%, 30%, and 40% of absolute back-squat strength. Ground-reaction forces and joint kinematics were captured using a 16-camera motion-capture system integrated with 2 in-ground force plates. Limb lengths and cross-sectional areas were defined using 3-dimensional photonic scans. A repeated-measures analysis of variance determined the interaction between system and joint load-power profiles, whereas a multiregression analysis defined the explained variance of athlete-dependent characteristics on the load that maximized system power.
System and isolated hip, knee, and ankle peak powers were maximized across a spectrum of loads between and within sports; power values were not significantly different across loads. A positive shift in the timing of hip and ankle peak powers corresponded to a significant (P < .05) positive shift in the timing of system peak power to occur closer to toe-off. An optimal 3-input combination of athlete-dependent characteristics accounted for 68% (P < .001) of the explained variance in the load that maximized system peak power.
The load maximizing system power is athlete-dependent, with a mixture of training and heredity-related characteristics influencing CMJ load-power profiles. The authors recommend that a combination of relative loads be individually prescribed to maximize the generation and translation of system CMJ power.
Rugby union (RU) is an intermittent team sport, with diverse playing positions, played internationally by both men and women. Considerable scientific attention has been devoted to men’s RU, however ...despite the growth in the women’s professional game, there is a significant lack of available physiological and normative data. The purpose of the present study was to investigate positional variation in countermovement jump characteristics from elite women’s RU players. Qualitative data were collected from women’s Rugby World Cup (2017) competitors (n = 86; age: 27 ± 5 years; body mass: 77.8 ± 10.6 kg; height: 1.69 ± 0.07 cm) and jump data (countermovement jumps) were collected using a 1200 Hz force platform (n = 63). Athletes were divided into positional unit (backs: n = 39 and forwards: n = 47) and by positional subgroups. Backs had greater jump height (ES = 0.72, 95%CL ± 0.50), relative power output (ES = 0.84, 95%CL ± 0.50), relative force production (ES = 0.62, 95%CL ± 0.51) and reactive strength index (RSI; ES = 0.62, 95%CL ± 0.50), compared to forwards (for all, P < 0.02). Backrows, halves and back-three players had greater relative force, relative power and jump height, compared to the front and second rows ( P < 0.03; ES > 0.70). These data could aid in programming for long-term player development in women’s RU and could have implications for “readiness” to compete at international level.
Le rugby à XV (RU) est un sport d’équipe intermittent, avec des positions de jeu diverses, joué au niveau international par des hommes et des femmes. Une attention scientifique considérable a été consacrée au RU masculin, mais malgré la croissance du jeu professionnel féminin, il existe un manque important de données physiologiques et normatives disponibles. Le but de la présente étude était d’étudier la variation de position des caractéristiques des sauts avec contre-mouvement chez les joueuses élites de RU. Des données qualitatives ont été collectées auprès des compétiteurs de la Coupe du monde de rugby féminin (2017) (n = 86 ; âge : 27 ± 5 ans ; masse corporelle : 77,8 ± 10,6 kg ; taille : 1,69 ± 0,07 cm) et les données de saut (sauts avec contre-mouvement) ont été collectées à l’aide d’une plateforme de force de 1200 Hz (n = 63). Les athlètes ont été divisés en unités de position (arrière : n = 39 et avant : n = 47) et en sous-groupes de position. Les arrières avaient des valeurs plus élevées de hauteur de saut (ES = 0,72, 95 %CL ± 0,50), de puissance de sortie relative (ES = 0,84, 95 %CL ± 0,50), de production de force relative (ES = 0,62, 95 %CL ± 0,51) et d’indice de résistance réactive (RSI ; ES = 0,62, 95 %CL ± 0,50), par rapports aux avants (pour tous, P < 0,02). Les joueurs d’arrière-plan, de moitié et d’arrière-trois avaient une force relative, une puissance relative et une hauteur de saut plus grandes que les joueurs de première ligne et de deuxième ligne ( P < 0,03 ; ES > 0,70). Ces données pourraient aider à programmer le développement à long terme des joueurs dans le RU féminin et pourraient avoir des implications pour la préparation à la compétition au niveau international.
Many spiders and insects can perform rapid jumps from smooth plant surfaces. Here, we investigate how jumping spiders (
Pseudeuophrys lanigera
and
Sitticus pubescens
) avoid slipping when ...accelerating. Both species differed in the relative contribution of leg pairs to the jump.
P. lanigera
accelerated mainly with their long third legs, whereas their short fourth legs detached earlier. In contrast,
S. pubescens
accelerated mainly with their long fourth legs, and their short third legs detached earlier. Because of the different orientation (fourth-leg tip pointing backward, third-leg tip pointing forward), the fourth-leg tarsus pushed, whereas the third-leg tarsus pulled. High-speed video recordings showed that pushing and pulling was achieved by different attachment structures. In
P. lanigera
, third-leg feet made surface contact with setae on their distal or lateral claw tuft, whereas fourth-leg feet engaged the proximal claw tuft, and the distal tuft was raised off the ground.
S. pubescens
showed the same division of labour between proximal and distal claw tuft for pushing and pulling, but the claw tuft contact lasted longer and was more visible in the fourth than in the third legs. Experimental ablation of claw tufts caused accelerating spiders to slip, confirming that adhesion is essential for jumps from smooth substrates.
. Figure skating is a sport discipline requiring a combination of artistic and athletic skills. The triple Axel Paulsen (Axel or A) jump is the most technically difficult jump of all figure skating ...jumps, which is why it is on the top of the International Skating Union (ISU) Judging System Code of Points (CoP). The purpose of this research was to explore the technical differences between the single Axel (1A), the double Axel (2A), and the triple Axel (3A) and to determine which parameters are the most important for performing the triple Axel successfully, using 3D kinematic analysis.
. In the study, one Polish elite male junior skater was tested. Following the usual warm-up, the skater performed a series of jumps on the ice, which were recorded. Six jumps of each type were recorded (6 x 1A, 6 x 2A, and 6 x 3A). Three jumps which were the best technically were chosen for further analysis. The APAS 2000 system automatically calculated the centre of gravity of the skater (CG) and generated the kinematic data of each jump.
. The skater examined jumped higher when he was about to perform more rotations in the jump. The more rotations were to be made, the higher the jump was. Although the difference between the height of 2A and 3A was less than 10% and could not be considered significant, the height of 1A was significantly lower, by over 19%, that the height of the other two jumps. As also shown by previous research, the most substantial differences in the Axel jump technique were visible in the pre-take-off and take-off phases.
. We observed substantial differences in the movement technique and kinematic parameters of the pre-take-off phase in the triple Axel performance compared to the performance of the other two Axels. It can be assumed that decreasing the ankle joint angle in the pre-take-off phase was most essential in achieving rotations in the Axel jump. This substantial change in ankle flexion caused greater stress on the blade before the take-off, which resulted in a reduction of vertical velocity and enabled an increase in the vertical take-off angle.
Sensory lateralization in dogs (n = 74) was investigated in this study using our innovation, the Sensory Jump Test. This required the modification of head halters to create three different ocular ...treatments (binocular, right, and left monocular vision) for eye preference assessment in a jumping task. Ten jumps were recorded as a jump set for each treatment. Measurements recorded included (
i) launch and landing paws, (
ii) type of jump, (
iii) approach distance, (
iv) clearance height of the forepaw, hindpaw, and the lowest part of the body to clear the jump, and (
v) whether the jump was successful. Factors significantly associated with these jump outcomes included ocular treatment, jump set number, and replication number. Most notably, in the first jump set, findings indicated a left hemispheric dominance for the initial navigation of the Sensory Jump Test, as left monocular vision (LMV) compromised of jumping more than right monocular (RMV) and binocular vision, with a significantly reduced approach distance and forepaw clearance observed in dogs with LMV. However, by the third jump set, dogs undergoing LMV launched from a greater approach distance and with a higher clearance height, corresponding to an increase in success rate of the jump, in comparison with RMV and binocular vision dogs. A marginally non-significant RMV bias was observed for eye preference based on the laterality indices for approach distance (
P = 0.060) and lowest body part clearance height (
P = 0.067). A comparison between eye preference and launching or landing paws showed no association between these measures of sensory and motor laterality. To our knowledge, this is the first study to report on sensory lateralization in the dog, and furthermore, to compare both motor and sensory laterality in dogs.
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