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1.
Landing with a low knee flexion angle after volleyball block jumps may be associated with an increased risk of anterior cruciate ligament (ACL) injury. The aim of the present study was to identify the types of volleyball landings after blocks where the knee flexion angle is found to be under a critical knee flexion angle value of 30° at the instant of the first peak of the ground reaction force (GRF). Synchronized kinematic and kinetic data were collected for each trial. T-tests were used to determine if each knee flexion angle at the instant of the peak GRF was significantly different from the critical value of 30°. A repeated measures ANOVA was used to compare knee flexion angle, time to first peak and the magnitude of the first peak of the resultant GRF and knee stiffness. Significantly lower knee flexion angles were found in the “go” landing (p?=?.01, ES?=?0.6) and the “reverse” landing (p?=?.02, ES?=?0.6) only. The results for knee flexion angle and GRF parameters indicated a significant difference between a “reverse” and “go” and other types of landings, except the “side stick” landing for GRF. The “reverse” and “go” landings may present a risk for ACL injury due to the single-leg landing of these activities that have an associated mediolateral movement.  相似文献   

2.
ABSTRACT

This study investigated the between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights. Seventeen male basketball players performed drop jumps from 3 heights on two platforms in randomized orders. Vertical ground reaction force data were analysed with respect to the lead limb (i.e. the limb stepping off the raised platform first) and trail limb. Peak forces and loading rates of each limb were calculated. The absolute time differential between the two limbs at initial ground contact and takeoff were determined. The frequency of symmetrical landing and taking off with “both limbs together” were counted using 3 time windows. Results showed that the lead limb displayed higher peak forces and loading rates than the trail limb across all heights (p <.05). As drop height increased, the absolute time differentials decreased at initial ground contact (p <.001) but increased at takeoff (p =.035). The greater the preset time window, the more landings and takeoffs were classified as bilaterally symmetrical. In conclusion, higher drop heights allowed subjects to become more bilaterally symmetrical in the timing of landing but this reduction in temporal asymmetry did not accompany with any reduction in kinetic asymmetry.  相似文献   

3.
The ankle joint’s role in shock absorption during landing has been researched in many studies, which have found that landing with higher amounts of plantarflexion (PF) results in lower peak vertical ground reaction forces and loading rates. However, there has not yet been a study that compares drop landings within participants along a quantitative continuum of PF angles. Using a custom-written real-time feedback program, participants adjusted their ankles to an instructed PF angle and dropped onto two force platforms. For increasing PF, peak ground reaction force and peak loading rate during weight acceptance decreased significantly. The hip’s contribution to peak support moment decreased as PF at initial contact increased up to 30°. The ankle and knee contributions increased over this same continuum of PF angles. There appears to be no optimal PF angle based on peak ground reaction force and loading rate measurements, but there may be an optimum where joint contributions to peak support moment converge and the hip moment’s contribution is minimised.  相似文献   

4.
ABSTRACT

Biomechanical analysis has typically been confined to a laboratory setting. While attempts have been made to take laboratory testing into the field, this study was designed to assess whether augmented reality (AR) could be used to bring the field into the laboratory. This study aimed to measure knee load in volleyball players through a jump task incorporating AR while maintaining the perception-action couplings by replicating the visual features of a volleyball court. Twelve male volleyball athletes completed four tasks: drop landing, hop jump, spike jump, and spike jump while wearing AR smart glasses. Biomechanical variables included patellar tendon force, knee moment and kinematics of the ankle, knee, hip, pelvis and thorax. The drop landing showed differences in patellar tendon force and knee moment when compared to the other conditions. The hop jump did not present differences in kinetics when compared to the spike conditions, instead of displaying the greatest kinematic differences. As a measure of patellar tendon loading the AR condition showed a close approximation to the spike jump, with no differences present when comparing landing forces and mechanics. Thus, AR may be used in a clinical assessment to better replicate information from the competitive environment.  相似文献   

5.
ABSTRACT

The lateral tilt of the arms accompanied by trunk lateral tilt is a typical blocking manoeuvre in volleyball. However, during this unanticipated blocking movement, an associated risk of ACL injury may result. The aim of the present study was to compare associative ACL risk factors at the initial contact and the first and second peak of VGRF during an unanticipated blocking movement with different arm positions. Synchronized kinematic and kinetic data were collected for each trial of each condition. Student paired t-tests and effect size were used to determine differences between two conditions (S – with arms straight up from the body) and (T – with the arms and trunk laterally tilted). The results showed that the T condition significantly decreases knee flexion, increases VGRF at the foot contact, first peak force and increases the valgus moment at the first peak force. The values of the associated risk factors for a non-contact ACL injury appear to be related to the tilted arm position accompanied by trunk tilt towards to right lower limb during landing. The players should be taught to land with greater knee flexion and, if possible, a double-leg landing to decrease right lower limb loading during the blocking manoeuvre.  相似文献   

6.
Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P?相似文献   

7.
Dancers are exposed to the effects of repetitive jumping and leaping as are other athletes that tend to develop patellar tendinopathy. Greater vertical ground reaction forces occur during landing from a dance leap than during takeoff and during other common athletic activities. The purposes of this study were: (1) to compare the landing ground reaction force profiles of participants with and without clinically diagnosed patellar tendinopathy, and (2) to determine the strength of the relationship between landing angle, and braking impulse. Eighteen elite pre-professional dancers (12 healthy, 6 with patellar tendinopathy; both groups 50% male) performed sauts de chat for kinetic and kinematic analysis. Dancers with patellar tendinopathy demonstrated greater peak vertical ground reaction force and impulse (36% and 15% greater, respectively). Dancers with patellar tendinopathy demonstrated greater peak braking ground reaction force and impulse (82% and 126% greater, respectively). Landing angle explained 67% of the braking impulse. Dancers with patellar tendinopathy exhibited greater vertical and braking impulses than healthy dancers. Braking impulse was strongly correlated with landing angle. While there was no difference between groups in landing angle, dancers with patellar tendinopathy exhibited greater braking impulse than their non-tendinopathic counterparts, even at similar landing angles.  相似文献   

8.
High impact forces during gymnastic landings are thought to contribute to the high rate of injuries. Lower limb joint flexion is currently limited within gymnastic rules, yet might be an avenue for reduced force absorption. This study investigated whether lower limb flexion during three gymnastic landings was related to force. Differences between landings were also explored. Twenty-one elite women's artistic gymnasts performed three common gymnastic techniques: drop landing (DL), front and back somersaults. Ankle, knee, and hip angles, and vertical ground reaction force [(vGRF) magnitude and time to peak], were measured using three-dimensional motion analysis and force platform. The DL had significantly smaller peak vGRF, greater time to peak vGRF and larger lower limb flexion ranges than landing from either somersault. Peak vGRF and time to peak vGRF were inversely related. Peak vGRF was significantly reduced in gymnasts who landed with greater hip flexion, and time to peak was significantly increased with increasing ankle, knee, and hip flexion. Increased range of lower limb flexion should be encouraged during gymnastic landings to increase time to peak vGRF and reduce high impact force. For this purpose, judging criteria limitations on lower limb flexion should be reconsidered.  相似文献   

9.
Abstract

Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P < 0.05) were found between the sexes for block, set, and spike but not for the jump serve. The frequency of landings on one foot was related to court position and the trajectory of the sets: when spiking faster sets, the players were more likely to use a one-footed landing. The present results should help coaches and physiotherapists to devise appropriate training and prevention programmes, and reveal the need for further detailed biomechanical investigations of the relationships between landings and knee injuries.  相似文献   

10.
The aim of this study was to examine the effect of opposition and gender on knee kinematics and ground reaction force during landing from a volleyball block jump. Six female and six male university volleyball players performed two landing tasks: (a) an unopposed and (b) an opposed volleyball block jump and landing. A 12-camera motion analysis system (120 Hz) was used to record knee kinematics, and a force platform (600 Hz) was used to record ground reaction force during landing. The results showed a significant effect for level of opposition in peak normalized ground reaction force (p = .04), knee flexion at ground contact (p = .003), maximum knee flexion (p = .001), and knee flexion range of motion (p = .003). There was a significant effect for gender in maximum knee flexion (p = .01), knee flexion range of motion (p = .001), maximum knee valgus angle (p = .001), and knee valgus range of motion (p = .001). The changes in landing biomechanics as a result of opposition suggest future research on landing mechanics should examine opposed exercises, because opposition may significantly alter neuromuscular responses.  相似文献   

11.
The purpose of this study was to examine changes in landing performance during fatigue that could result in increased stress fracture injury risk. Five participants performed nonfatigued and fatigued drop landings (0.60 m), while ground reaction force (GRF), electromyographic (EMG) activity, and kinematics were recorded. Fatigue was defined as a 5-20% reduction in vertical jumping performance. Single-subject analyses revealed that all participants were affected (p < or = .05) by fatigue. Post hoc comparisons revealed a group effect (p < or = .05) for selected variables. Participants landed with (a) less joint flexion at contact and used a greater range of motion, (b) greater GRF peaks and loading rates, and (c) less EMG activity. These changes were consistent with greater risk of stress fracture.  相似文献   

12.
聚焦跑步时髌股关节生物力学特征,探究穿着不同极简指数(MI)跑鞋对髌股关节接触力、应力等的即刻影响。选取15名习惯后跟着地的健康男性跑者,分别穿着两种MI跑鞋(MI 86%极简跑鞋和MI 26%缓冲跑鞋),使用Vicon红外运动捕捉系统、Kistler三维测力台同步采集3.33 m/s(速度变化范围±5%)跑速下的膝、踝关节运动学和地面反作用力,通过逆向动力学等计算股四头肌肌力、髌股关节接触力、髌股关节接触面积以及髌股关节接触应力。结果显示:两种跑鞋条件下的冲击力峰值和蹬地力峰值均无明显差异。与缓冲跑鞋相比,穿着极简跑鞋跑步时,膝关节最大屈曲角度显著降低(P<0.01);髌股关节接触面积显著减小(P<0.01);膝关节伸肌峰值力矩显著下降(P<0.01);髌股关节接触力和应力峰值均显著减小(P<0.05)。研究表明,相比缓冲跑鞋,穿着极简跑鞋在未影响触地后冲击力峰值的同时,通过降低伸膝力矩大幅度减少髌股关节接触力(下降17.02%)、降低髌股关节接触应力,从而有效改善支撑期髌股关节负荷,为进一步减小髌股关节疼痛综合征风险提供可能。  相似文献   

13.
Artistic gymnasts are frequently exposed to both low- and high-magnitude loads through impacts with the apparatus. These impact loads are thought to be associated with the high injury rates observed in gymnastics. Due to the variable apparatus and surfaces in gymnastics, impact loads during training are difficult to quantify. This study aimed to use triaxial accelerometers mounted on the back to assess impact loading during jumping and landing tasks. Twelve participants were fitted with an accelerometer on their upper and lower back, before performing a continuous hopping task, as well as drop landings and rebound jumps from various heights (37.5, 57.5, and 77.5 cm) onto a force platform. Peak resultant acceleration (PRA) was low-pass filtered with four cut-off frequencies (8, 15, 20, and 50 Hz). Filtering of PRA with the 20 Hz cut-off frequency showed the highest correlations between ground reaction force (GRF) and PRA. PRA recorded at the upper back, filtered with a 20 Hz cut-off frequency, appears to provide a good estimate of impact loading for continuous hopping and rebound jumps, but less so for drop landings since correlations between GRF and PRA were only significant when landing from 57.5 cm.  相似文献   

14.
The number and type of landings performed after blocking during volleyball matches has been related to the potential risk of ACL injury. The aim of the present study was to determine whether gender affects the frequency of specific blocking landing techniques with potential risk of ACL injury from the perspective of foot contact and subsequent movement after the block used by volleyball players during competitive matches. Three matches involving four female volleyball teams (fourteen sets) and three matches involving four male volleyball teams (thirteen sets) in the Czech Republic were analyzed for this study. A Pearson chi-square test of independence was used to detect the relationship between gender and different blocking techniques. The results of the present study showed that gender affected single-leg landings with subsequent movement in lateral direction and double-leg landings. Although the total number of landings was lower for male athletes than for female athletes, a larger portion of male athletes demonstrated single leg landings with a subsequent movement than female athletes. Single leg landings with a subsequent movement have a higher potential risk of ACL injury.  相似文献   

15.
Movement patterns during landing have been suggested to be related to injury risk. The purpose of this study was to determine the inter-session reliability of kinematic variables and ground reaction forces during landing in a population of male recreational athletes after a counter movement jump. Both unipodal and bipodal landings were evaluated. Furthermore, the possibility to improve landing reliability with a verbal instruction was also studied. Twenty-four male volunteers with no history of lower extremity trauma were randomly assigned to two groups (with and without verbal landing instruction). An optoelectronic 3D system and force plates were used to measure the lower limb joint angles and the ground reaction forces during landing. Intraclass correlation values show moderate to excellent inter-session reliability for the bipodal task (ICC average: 0.80, range: 0.46–0.97) and poor to excellent reliability for the unipodal task (ICC average: >0.75, range: 0.20–0.95). However, large standard errors of measurement values at the ankle joint at impact (27.6?±?11.5°) and for the vertical ground reaction forces (394?±?1091 N) show that some variables may not be usable in practice. The verbal instruction had a negative effect on the reliability of unipodal landing but improved the reliability of bipodal landing. These findings show that the reliability of a landing task is influenced by its motor complexity as well as the instruction given to the subject.  相似文献   

16.
沈富麟  金赟 《体育科研》2009,30(1):85-88
从国家男排部分上，海籍运动员的大力跳发球技术测试效果入手，分析与诊断影响其大力跳发球技．概动作的主要因素，并就发球抛球、发球速度的固定等两方面进行具体的分析与讨论。同时对两名优秀选手的腰背肌肉力量进行监测、综合评价其大力跳发球技术动作利弊特征，并做相关的比较研究。经运动学分析，总体上两名运动员的大力跳发球抛球时间偏短、击球点偏低，一造成共发球球速慢且失误率高等，并建设性的提出跳发球技术动作诊断应因人而异，最大限度地挖掘个人技术动作的局部潜优势。  相似文献   

17.
Abstract

High ground reaction forces during the front foot contact phase of the bowling action are believed to be a major contributor to the high prevalence of lumbar stress fractures in fast bowlers. This study aimed to investigate the influence of front leg technique on peak ground reaction forces during the delivery stride. Three-dimensional kinematic data and ground reaction forces during the front foot contact phase were captured for 20 elite male fast bowlers. Eight kinematic parameters were determined for each performance, describing run-up speed and front leg technique, in addition to peak force and time to peak force in the vertical and horizontal directions. There were substantial variations between bowlers in both peak forces (vertical 6.7 ± 1.4 body weights; horizontal (braking) 4.5 ± 0.8 body weights) and times to peak force (vertical 0.03 ± 0.01 s; horizontal 0.03 ± 0.01 s). These differences were found to be linked to the orientation of the front leg at the instant of front foot contact. In particular, a larger plant angle and a heel strike technique were associated with lower peak forces and longer times to peak force during the front foot contact phase, which may help reduce the likelihood of lower back injuries.  相似文献   

18.
ABSTRACT

Knee joint coordination during jump landing in different directions is an important consideration for injury prevention. The aim of the current study was to investigate knee and hip kinematics on the non-dominant and dominant limbs during landing. A total of 19 female volleyball athletes performed single-leg jump-landing tests in four directions; forward (0°), diagonal (30° and 60°) and lateral (90°) directions. Kinematic and ground reaction force data were collected using a 10-camera Vicon system and an AMTI force plate. Knee and hip joint angles, and knee angular velocities were calculated using a lower extremity model in Visual3D. A two factor repeated measures ANOVA was performed to explore limb dominance and jump direction. Significant differences were seen between the jump directions for; angular velocity at initial contact (p < 0.001), angular velocity at peak vertical ground reaction force (p < 0.001), and knee flexion excursion (p = 0.016). Knee coordination was observed to be poorer in the early phase of velocity-angle plot during landing in lateral direction compared to forward and diagonal directions. The non-dominant limb seemed to have better coordination than the dominant limb during multi-direction jump landing. Therefore, dominant limbs appear to be at a higher injury risk than non-dominant limbs.  相似文献   

19.
Overuse injuries, resulting from repetitive subacute impact loading, are a problem in high-performance sports. Monitoring of impact loading may aid in the prevention of these injuries. The current study aimed to establish the intra-day and inter-day reliability of a tri-axial accelerometer to assess impact loading during jumping and landing tasks. Twelve participants wore an accelerometer on their upper and lower back. They performed a continuous hopping task as well as drop landings and rebound jumps from three drop heights (37.5, 57.5 and 77.5 cm), peak resultant acceleration (PRA) was calculated for all tasks. The tasks were performed twice, one week apart at the same time of day. The difference in the mean, intra-class correlation coefficient, coefficient of variation and Cohen’s effect size were calculated as measures of reliability. PRA showed good intra-day reliability for the hopping task. Inter-day reliability of the PRA was moderate to good across all tasks. Reliability of PRA was slightly higher when accelerations were recorded on the lower back compared to the upper back. To assess impact loading, during continuous hopping, drop landings and rebound jumps, PRA recorded at both the upper and lower back appears to be a reliable measure.  相似文献   

20.
This study investigated the effects of body mass and shoe midsole hardness on kinetic and perceptual variables during the performance of three basketball movements: (1) the first and landing steps of layup, (2) shot-blocking landing and (3) drop landing. Thirty male basketball players, assigned into “heavy” (n = 15, mass 82.7 ± 4.3 kg) or “light” (n = 15, mass 63.1 ± 2.8 kg) groups, performed five trials of each movement in three identical shoes of varying midsole hardness (soft, medium, hard). Vertical ground reaction force (VGRF) during landing was sampled using multiple wooden-top force plates. Perceptual responses on five variables (forefoot cushioning, rearfoot cushioning, forefoot stability, rearfoot stability and overall comfort) were rated after each movement condition using a 150-mm Visual Analogue Scale (VAS). A mixed factorial analysis of variance (ANOVA) (Body Mass × Shoe) was applied to all kinetic and perceptual variables. During the first step of the layup, the loading rate associated with rearfoot contact was 40.7% higher in the “heavy” than “light” groups (P = .014) and 12.4% higher in hard compared with soft shoes (P = .011). Forefoot peak VGRF in a soft shoe was higher (P = .011) than in a hard shoe during shot-block landing. Both “heavy” and “light” groups preferred softer to harder shoes. Overall, body mass had little effect on kinetic or perceptual variables.  相似文献   

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