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1.
Volleyball     
The purpose of this investigation was to detect whether differences exist concerning the dynamic and kinematic parameters of vertical squat jump (SJ) on rigid (RS) and sand (SS) surface. Fifteen elite male beach volleyball players (age: 25.6±6.2 years; height: 188.0±3.5cm; body mass: 83.2±6.0 kg; mean ±SD, respectively) performed SJ. Force platform and kinematic analyses were used with paired sample T‐tests to evaluate the differences. Vertical jump height was significantly smaller (p < .001) on SS than RS. Maximal force and maximal power were significantly higher on RS than SS (p < .05 and p < .01 respectively). Impulse time was larger in SS but with no significant difference (p = .286). Kinematic analysis revealed significant differences between the values of ankle joint during starting posture (p < .01) and of hip joint at the moment of take‐off (p < .05). Ankle joint range of motion and angular velocity was larger in SS (p < .05). In conclusion, SJ height on SS was smaller than on RS because of the compliance and the instability of the sand. This resulted in a reduction in maximum force and take‐off velocity. Furthermore, the compliance of SS made it hard for the ankle to push along the vertical axis of the movement of the body and as a result it slipped behind in an attempt to maximise propulsion. As a result, the body tries to balance and equalise this movement and move the hip to larger extension.  相似文献   

2.
Abstract

This study aimed to investigate the contributions of kinetic and kinematic parameters to inter-individual variation in countermovement jump (CMJ) performance. Two-dimensional kinematic data and ground reaction forces during a CMJ were recorded for 18 males of varying jumping experience. Ten kinetic and eight kinematic parameters were determined for each performance, describing peak lower-limb joint torques and powers, concentric knee extension rate of torque development and CMJ technique. Participants also completed a series of isometric knee extensions to measure the rate of torque development and peak torque. CMJ height ranged from 0.38 to 0.73 m (mean 0.55 ± 0.09 m). CMJ peak knee power, peak ankle power and take-off shoulder angle explained 74% of this observed variation. CMJ kinematic (58%) and CMJ kinetic (57%) parameters explained a much larger proportion of the jump height variation than the isometric parameters (18%), suggesting that coachable technique factors and the joint kinetics during the jump are important determinants of CMJ performance. Technique, specifically greater ankle plantar-flexion and shoulder flexion at take-off (together explaining 58% of the CMJ height variation), likely influences the extent to which maximal muscle capabilities can be utilised during the jump.  相似文献   

3.
The purpose of this study was to investigate the possible arm swing effect on the biomechanical parameters of vertical counter movement jump due to differences of the compliance of the take-off surface. Fifteen elite male beach-volleyball players (26.2 ± 5.9 years; 1.87 ± 0.05 m; 83.4 ± 6.0 kg; mean ± standard deviation, respectively) performed counter movement jumps on sand and on a rigid surface with and without an arm swing. Results showed significant (p < .05) surface effects on the jump height, the ankle joint angle at the lowest height of the body center of mass and the ankle angular velocity. Also, significant arm swing effects were found on jump height, maximum power output, temporal parameters, range of motion and angular velocity of the hip. These findings could be attributed to the instability of the sand, which resulted in reduced peak power output due to the differences of body configuration at the lowest body position and lower limb joints’ range of motion. The combined effect of the backward arm swing and the recoil of the sand that resulted in decreased resistance at ankle plantar flexion should be controlled at the preparation of selected jumping tasks in beach-volleyball.  相似文献   

4.
The purpose of this study was to analyze the kinematic variables that determine the performance of the standing long jump in children 6- to 12-years-old. There were 121 healthy children (58 girls) recorded while they performed the standing long jump test. All kinematic variables showed a significant correlation with calculated jump distance and measured jump distance, except for the knee joint angle at maximum shoulder extension angle, ankle joint angle at maximum shoulder extension angle, and shoulder joint angle at maximum knee flexion angle. Stepwise multiple regression analysis showed that sex, age, and body mass index accounted for 51.1% of the jump distance variance. Among all the kinematic variables, take-off distance and take-off speed were accounted for the most of the variation in the jump distance. Physical education teachers and coaches should consider special attention to these anthropometrics and kinematic aspects in improving the standing long jump performance in children.  相似文献   

5.
目的:通过分析我国优秀男子跳台滑雪运动员实地起跳阶段运动学、起跳运动模式等指标,探究影响我国男子跳台滑雪运动员飞行距离的主要起跳因素。方法:1)选择8名我国男子跳台滑雪运动员作为研究对象,在日本长野县白马村K90跳台训练基地采集3次起跳阶段二维运动学数据,采用广义估计模型(GEE)分析影响飞行距离的实地起跳阶段运动学因素。2)截取平昌冬奥会排名前10的男子跳台滑雪选手决赛起跳阶段视频数据,采用单因素方差分析研究国内外运动员起跳阶段特定时刻肢体角度差异。3)实验室内使用1台Z camera高速摄像机和1块Kistler 9281EA测力台采集运动员静蹲跳(squat jump,SJ)、反向跳(countermovement jump,CMJ)、模拟跳跃(imitation jump,IJ)、下落跳(drop jump,DJ)的动力学及运动学数据,采用Pearson相关分析检验实验室内运动学及动力学指标与飞行距离间的相关性。结果:1)在实地起跳阶段运动学方面,起跳起始时刻躯干与助滑道夹角、小腿与助滑道夹角、髋关节角、膝关节角,以及起跳阶段的髋关节峰值角速度、膝关节平均角速度、起跳结束时刻膝关节角及髋关节角为飞行距离的影响因素(P<0.05)。2)在起跳阶段运动模式及力量特点方面,IJ重心最低处膝外翻指数(r=0.731)、DJ膝外翻最小值(r=0.713)、CMJ起跳阶段地面反作用力峰值(r=0.710)、CMJ蹬伸冲量(r=0.752)、SJ(r=0.723)及CMJ起跳峰值功率(r=0.762)均与飞行距离呈正相关。3)对比国内外运动员起跳阶段特定时刻肢体角度发现,国外优秀运动员起跳起始时刻小腿与助滑道夹角(53.54°±3.14°)显著小于我国运动员(57.62°±4.62°),出台瞬间小腿与助滑道夹角(58.22°±2.13°)显著小于我国运动员(65.59°±3.84°),大腿与助滑道夹角(73.28°±6.15°)显著大于我国运动员(58.77°±3.16°),起跳阶段结束时刻髋关节角度(175.23°±1.96°)显著大于我国运动员(156.37°±13.13°)。结论:我国跳台滑雪运动员起跳阶段起跳起始时刻应尽量降低身体重心以减少阻力,并适当提高膝关节角来提高出台后肢体伸展程度。起跳过程中提高膝关节蹬伸力量,同时适当降低髋关节伸展速度,避免风阻对躯干造成不利影响。室内及实地训练过程中,应在提升蹬伸爆发力的同时避免膝关节过度外翻,提高蹬伸力量及传递效率。  相似文献   

6.
ABSTRACT

Chronic foot and ankle injuries are common in dancers; understanding how lower extremity loading changes in response to altered task goals can be beneficial for rehabilitation and injury prevention strategies. The purpose of this study was to examine mechanical demands during jump take-offs when the task goal was modified to focus on either increasing jump distance or increasing jump height. It was hypothesized that a jump strategy focused on height would result in decreased energetic demands on the foot and ankle joints. Thirty healthy, experienced female dancers performed saut de chat leaps while travelling as far as possible (FAR) or jumping as high as possible (UP). Ground reaction force (GRF) impulses and peak sagittal plane net joint moments and sagittal plane mechanical energy expenditure (MEE) of the metatarsophalangeal (MTP), ankle, knee, and hip joints were calculated. During take-off, vertical and horizontal braking GRF impulses were greater and horizontal propulsive GRF impulse was lower in the UP condition. MEE at the MTP, ankle, and hip joints was lower in UP, and MEE at the knee was higher in UP. These results suggest that a strategy focused on height may be helpful in unloading the ankle and MTP joints during dance leaps.  相似文献   

7.
Abstract

The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to “pull” on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum.  相似文献   

8.
ABSTRACT

Previous research suggests that landing mechanics may be affected by the mechanics of the preceding jump take-off. The purpose of the present study was to investigate whether jump take-off mechanics influence the subsequent landing mechanics. Female volleyball (n = 17) and ice hockey (n = 19) players performed maximal vertical jumps with forefoot and heel take-off strategies. During forefoot and heel jumps, participants were instructed to shift their weight to their forefoot or heel, respectively, and push through this portion of the foot throughout the jump. Jump mechanics were examined using 3D motion analysis, where lower extremity net joint moment (NJM) work, NJM, and segment angles were compared between forefoot and heel jumps using multivariate ANOVA. During jump take-off, participants performed more positive ankle plantar flexor and knee extensor NJM work in forefoot compared to heel jumps (P < 0.05). From initial foot contact to foot flat, participants performed more negative ankle plantar flexor and hip extensor NJM work during heel compared to forefoot jumps (P < 0.05). The present results demonstrate that using a heel take-off strategy results in a different distribution of lower extremity NJM work and NJM during landing compared to landings following forefoot jumps.  相似文献   

9.
In this study, we investigated the adjustments to posture, kinematic and temporal characteristics of performance made by lower limb amputees during the last few strides in preparation for long jump take-off. Six male unilateral trans-femoral and seven male unilateral trans-tibial amputees competing in a World Championships final were filmed in the sagittal plane using a 100-Hz digital video camera positioned so that the last three strides to take-off were visible. After digitizing using a nine-segment model, a range of kinematic variables were computed to define technique characteristics. Both the trans-femoral and trans-tibial athletes appeared to achieve their reduction in centre of mass during the flight phase between strides, and did so mainly by extending the flight time by increasing stride length, achieved by a greater flexion of the hip joint of the touch-down leg. The trans-tibial athletes appeared to adopt a technique similar to that previously reported for able-bodied athletes. They lowered their centre of mass most on their second last stride (-1.6% of body height compared with -1.4% on the last stride) and used a flexed knee at take-off on the last stride, but they were less able to control their downward velocity at touch-down (-0.4 m x s(-1)). Both this and their restricted approach speed (8.9 m x s(-1) at touch-down), rather than technique limitations, influenced their jump performance. The trans-femoral athletes lowered their centre of mass most on the last stride (-2.3% of body height compared with -1.6% on the second last stride) and, as they were unable to flex their prosthetic knee sufficiently, achieved this by abducting their prosthetic leg during the support phase, which led to a large downward velocity at touch-down (-0.6 m x s(-1)). This, combined with their slower approach velocity (7.1 m x s(-1) at touch-down), restricted their performance.  相似文献   

10.
The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to "pull" on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum.  相似文献   

11.
To determine the contributions of the motions of the body segments to the vertical ground reaction force (Fz), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm swing. Linear kinematic, Fz, and joint torque data were computed and compared using repeated measures analysis of variance. Maximum jump height was significantly larger in the arm swing jumps compared to the no arm swing jumps and was due to both a higher height of the center of mass (CM) at takeoff (54%) and a larger vertical velocity of the CM at takeoff (46%). The net vertical impulse created during the propulsive phase of the arm swing jumps was greater due to a trend of an increased duration (0.021 s) of the propulsive phase and not to larger average values of Fz. In the arm swing jumps, the arm motion resulted in the arms making a larger maximal contribution to Fz during the middle of the propulsive phase and decreased the negative contribution of the trunk-head and thigh to Fz late in the propulsive phase. Last, the arm swing decreased the extensor torques at the hip (13%), knee (10%), and ankle (10%) early in the propulsive phase but augmented these same extensor torques later in the propulsive phase.  相似文献   

12.
Abstract

In this study, we investigated the adjustments to posture, kinematic and temporal characteristics of performance made by lower limb amputees during the last few strides in preparation for long jump take-off. Six male unilateral trans-femoral and seven male unilateral trans-tibial amputees competing in a World Championships final were filmed in the sagittal plane using a 100-Hz digital video camera positioned so that the last three strides to take-off were visible. After digitizing using a nine-segment model, a range of kinematic variables were computed to define technique characteristics. Both the trans-femoral and trans-tibial athletes appeared to achieve their reduction in centre of mass during the flight phase between strides, and did so mainly by extending the flight time by increasing stride length, achieved by a greater flexion of the hip joint of the touch-down leg. The trans-tibial athletes appeared to adopt a technique similar to that previously reported for able-bodied athletes. They lowered their centre of mass most on their second last stride (?1.6% of body height compared with ?1.4% on the last stride) and used a flexed knee at take-off on the last stride, but they were less able to control their downward velocity at touch-down (?0.4 m · s?1). Both this and their restricted approach speed (8.9 m · s?1 at touch-down), rather than technique limitations, influenced their jump performance. The trans-femoral athletes lowered their centre of mass most on the last stride (?2.3% of body height compared with ?1.6% on the second last stride) and, as they were unable to flex their prosthetic knee sufficiently, achieved this by abducting their prosthetic leg during the support phase, which led to a large downward velocity at touch-down (?0.6 m · s?1). This, combined with their slower approach velocity (7.1 m · s?1 at touch-down), restricted their performance.  相似文献   

13.
Purpose: There is uncertainty as to which knee angle during a squat jump (SJ) produces maximal jump performance. Importantly, understanding this information will aid in determining appropriate ratios for assessment and monitoring of the explosive characteristics of athletes. Method: This study compared SJ performance across different knee angles—90º, 100º, 110º, 120º, 130º, and a self-selected depth—for jump height and other kinetic characteristics. For comparison between SJ and an unconstrained dynamic movement, participants also performed a countermovement jump from a self-selected depth. Thirteen participants (Mage = 25.4 ± 3.5 years, Mheight = 1.8 ± 0.06 m, Mweight = 79.8 ± 9.5 kg) were recruited and tested for their SJ performance. Results: In the SJ, maximal jump height (35.4 ± 4.6 cm) was produced using a self-selected knee angle (98.7 ± 11.2°). Differences between 90°, 100°, and self-selected knee angles for jump height were trivial (ES ± 90% CL = 90°–100° 0.23 ± 0.12, 90°–SS ?0.04 ± 0.12, 100°–SS ?0.27 ± 0.20; 0.5–2.4 cm) and not statistically different. Differences between all other knee angles for jump height ranged from 3.8 ± 2.0 cm (mean ± 90% CL) to 16.6 ± 2.2 cm. A similar outcome to jump height was observed for velocity, force relative to body weight, and impulse for the assessed knee angles. Conclusions: For young physically active adult men, the use of a self-selected depth in the SJ results in optimal performance and has only a trivial difference to a constrained knee angle of either 90° or 100°.  相似文献   

14.
ABSTRACT

This study examined potential differences between maximally cushioned (MAX) shoes and standard cushioned (STND) shoes during countermovement vertical jump (CMVJ) performance. Twenty-one males (23[2] y; 86.5[15.4] kg; 179.8[6.3] cm) completed eight jumps each in MAX and STND shoes while three-dimensional kinematic and kinetic data were collected. Paired-samples t-tests (α = 0.05) and Cohen’s d effect sizes (ES) were used to compare the following variables: vertical jump displacement, jump time, hip, knee and ankle joint angles at the start of the countermovement, the end of the unloading phase, the end of the eccentric phase, and at takeoff, peak joint power, and the joint contributions to total lower extremity work during the eccentric and concentric phases. The ankle was more dorsiflexed at the end of the countermovement in the MAX shoe (p = 0.002; ES = 0.55) but greater plantarflexion occurred in the STND shoes at takeoff (p = 0.028; ES = 0.56). No other differences were observed. The result of this study suggests that unique ankle joint angular positioning may be employed when wearing MAX versus STND shoes. Since the unique ankle joint positioning did not alter jump performance, potential MAX footwear users might not need to consider the potential for altered CMVJ performance when determining whether to adopt MAX footwear.  相似文献   

15.
This study biomechanically quantified the movement patterns for six elite goalkeepers making diving saves to their preferred and non-preferred side at three different dive heights. Synchronised three-dimensional kinematic and kinetic biomechanical data analysis found diving direction to significantly (P < 0.05) influence the movement patterns of the diving save. The non-preferred side displayed greater lateral rotation of the pelvis and thorax at the initiation event. These over-rotational differences were reduced during the time on plate phase with the thorax displaying no significant difference at take-off; although a difference still remained for the pelvis. These over rotations were subsequently linked to greater peak knee joint moments, lower peak ankle joint moments, less hip extension at take-off, and for the centre of mass (COM) to travel slower and less directly to the ball, as measured by the net projection angle at take-off. These results indicate that joint movements in the transverse plane at or before the initiation event for the dive for the pelvis and thorax are the causation for subsequent asymmetries. These observed differences indicate that there is an advantage in having prior knowledge of limb preference in an opposing goalkeeper.  相似文献   

16.
Abstract

The aim of the present study was to investigate the kinematic and kinetic differences in the execution of vertical jumps between individuals with good and poor ankle dorsiflexion. Fifteen physical education students were assigned to the flexible group (FG), while another 15 were assigned to the inflexible group (IFG). The two groups executed countermovement jumps (CMJ) and drop jumps from a 60 cm height (DJ60). For the CMJ, the FG jumped higher (32.0 ± 4.0 cm vs. 30.2 ± 4.9 cm, P = 0.27) and used a greater range of motion in all leg joints. The IFG jumpers raised their heels off the ground and had a greater horizontal distance between the centre of mass of the trunk and the centre of the hip joint (LCMh 25.6 ± 3.4 cm vs. 30.9 ± 4.3 cm, P < 0.001). In the DJ60 the FG jumped higher (22.4 ± 5.9 cm vs. 19.5 ± 4.6 cm, P = 0.14) with a greater vertical shift of the body centre of mass (BCM) (S = 0.45 ± 0.11 cm vs. 0.36 ± 0.05 cm, P < 0.01) and better joint coordination. The IFG jumpers changed the position of their trunk and heels depending on the jump type. Trainers should reconsider the technical issues of vertical jumps according to the flexibility of the ankle joint.  相似文献   

17.
跳远起跳技术的运用在学界一直存有争议,为探讨跳远起跳技术的生物力学原理,选取跳远起跳动作作为研究对象,建立起跳动作的数学模型并在计算机上实施基于肌肉动力学层面的运动模拟。模拟结果表明:在增大人体重心垂直速度和重心的腾起角方面,膝关节肌较之髋关节肌都有更为显著的作用;在相同的着地距离下,增大小腿环节角与增大大腿环节角相比明显有利。  相似文献   

18.
This study aimed to clarify the differences between the horizontal single-leg rebound jump (HJ) and vertical single-leg rebound jump (VJ) in terms of three-dimensional joint kinetics for the take-off leg, while focusing on frontal and transverse plane movements. Eleven male track and field athletes performed HJ and VJ. Kinematic and kinetic data were calculated using data recorded with a motion capture system and force platforms. The hip abduction torque, trunk lateral flexion torque (flexion for the swing-leg side), hip external and internal torque, trunk rotational torque, and the powers associated with these torques were larger when performing HJ because of resistance to the impact ground reaction force and because of pelvic and posture control. Pelvic rotation was noted in HJ, and this was controlled not only by the hip and trunk joint torque from the transverse plane but also by the hip abduction torque. Therefore, hip and trunk joint kinetics in the frontal and transverse plane play an important role in a single-leg jump, regardless of the jumping direction, and may also play a more important role in HJ than in VJ.  相似文献   

19.
Twenty-five volleyball players (14 males, 11 females) were videotaped (60Hz) performing countermovement vertical jumps with and without an arm swing. Ground reaction force and video-based coordinate data were collected simultaneously. The resultant joint force and torque at the hip, knee, ankle and shoulder for two trials per subject per condition were computed and normalized. Average kinematic, resultant joint force and torque data were compared using repeated-measures analysis of variance. Larger values were recorded for the vertical velocity of the centre of mass at take-off in the jumps with (mean 2.75, s=0.3m.s-1) versus without (mean 2.44, s= 0.23m.s-1) an arm swing. The jumps with no arm swing produced larger torques at the hip during the first third of the propulsive phase (from zero to maximum vertical velocity of the centre of mass). During the final two-thirds of the propulsive phase, the arm swing augmented hip extensor torques by slowing the rate of trunk extension and placing the hip extensor muscles in slower concentric conditions that favoured the generation of larger forces and resultant joint torques. During the first two-thirds ofthe propulsive phase, knee extensor torque increased by 28% in the jumps with an arm swing, but maintained a relatively constant magnitude in the jumps with no arm swing.  相似文献   

20.
Twenty-five volleyball players (14 males, 11 females) were videotaped (60 Hz) performing countermovement vertical jumps with and without an arm swing. Ground reaction force and video-based coordinate data were collected simultaneously. The resultant joint force and torque at the hip, knee, ankle and shoulder for two trials per subject per condition were computed and normalized. Average kinematic, resultant joint force and torque data were compared using repeated-measures analysis of variance. Larger values were recorded for the vertical velocity of the centre of mass at take-off in the jumps with (mean 2.75, s = 0.3 m.s-1) versus without (mean 2.44, s = 0.23 m.s-1) an arm swing. The jumps with no arm swing produced larger torques at the hip during the first third of the propulsive phase (from zero to maximum vertical velocity of the centre of mass). During the final two-thirds of the propulsive phase, the arm swing augmented hip extensor torques by slowing the rate of trunk extension and placing the hip extensor muscles in slower concentric conditions that favoured the generation of larger forces and resultant joint torques. During the first two-thirds of the propulsive phase, knee extensor torque increased by 28% in the jumps with an arm swing, but maintained a relatively constant magnitude in the jumps with no arm swing.  相似文献   

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