The performance of the ice hockey slap and wrist shots: the effects of stick construction and player skill

The purpose of this study was to examine the interaction of players’ skill level, body strength, and sticks of various construction and stiffness on the performance of the slap and wrist shots in ice hockey. Twenty male and twenty female subjects were tested. Ten of each gender group were considered skilled and ten unskilled. In addition to general strength tests, each subject performed the slap and wrist shots with three stick shafts of different construction and stiffness. Shot mechanics were evaluated by simultaneously recording ground reaction forces from a force plate, stick movement and bending from high speed filming and peak puck velocity from a radar gun. Data were analysed with a 4-way repeated measures ANOVA for several dependent variables including peak puck velocity, peak Z (vertical) force, peak bending and stick to ground angles, peak angular deflection of the shaft, and hand placement on the stick. The results indicated that: 1) the slap shot was much faster than the wrist shot corresponding to greater vertical loading force, stick bending, and greater width of the hand placement; 2) the puck velocity was influenced by skill level and body strength but not stick type; and, 3) that skilled players were able to generate more vertical force and bend of the stick, in part, by adjusting their hand positions on the stick. Further studies are needed to address the specific influence of body strength and skill on the techniques of these shots and in relation to stick material and construction properties.     

Skating start propulsion: three-dimensional kinematic analysis of elite male and female ice hockey players

The forward skating start is a fundamental skill for male and female ice hockey players. However, performance differences by athlete’s sex cannot be fully explained by physiological variables; hence, other factors such as skating technique warrant examination. Therefore, the purpose of this study was to evaluate the body movement kinematics of ice hockey skating starts between elite male and female ice hockey participants. Male (n = 9) and female (n = 10) elite ice hockey players performed five forward skating start accelerations. An 18-camera motion capture system placed on the arena ice surface captured full-body kinematics during the first seven skating start steps within 15 meters. Males’ maximum skating speeds were greater than females. Skating technique sex differences were noted: in particular, females presented ~10° lower hip abduction throughout skating stance as well as ~10° greater knee extension at initial ice stance contact, conspicuously followed by a brief cessation in knee extension at the moment of ice contact, not evident in male skaters. Further study is warranted to explain why these skating technique differences exist in relation to factors such as differences in training, equipment, performance level, and anthropometrics.     

A method for personalising the blade size for competitors in flatwater kayaking

The intent of this project was to explore the feasibility of personalising the paddle blade size for individual flatwater kayakers based on their power output profiles. Twelve elite male kayakers performed on a kayak ergometer at the same intensity and resistance that they would normally experience while paddling at race pace for 500 m on the water. The kayak ergometer was instrumented so that power profiles could be determined from the instantaneous force and velocity of the representative centre point of the paddle blade. From the power profile information, the researchers calculated a personalised blade size that was expected to improve performance for those kayakers differing more than 5% from the calculated ‘ideal’ size. For the elite kayakers studied, it was recommended that seven of the paddlers should increase their blade size by approximately 5–10%. For the remaining five paddlers, the results indicated that their current blade sizes were within the expected measurement error of their predicted ideal value and should be retained. It is anticipated that this research will provide the theoretical rationale for elite kayakers to see the need to personalise their blade size based on their own muscle power profiles.     

Does performance level affect initial ball flight kinematics in finger and wrist-spin cricket bowlers?

Spin bowling plays a fundamental role within the game of cricket yet little is known about the initial ball kinematics in elite and pathway spin bowlers or their relationship to performance. Therefore, the purpose of this study was to record three-dimensional ball kinematics in a large and truly high level cohort of elite and pathway finger-spin (FS) and wrist-spin (WS) bowlers, identifying potential performance measures that can be subsequently used in future research. A 22-camera Vicon motion analysis system captured retro-reflective markers placed on the seam (static) and ball (dynamic) to quantify ball kinematics in 36 FS (12 elite and 24 pathway) and 20 WS (eight elite and 12 pathway) bowlers. Results indicated that FS bowlers delivered the ball with an increased axis of rotation elevation, while wrist-spin bowlers placed greater amounts of revolutions on the ball. It also highlighted that ball release (BR) velocity, revolutions and velocity/revolution index scores for both groups and seam stability for FS bowlers, and seam azimuth angle and spin axis elevation angle for WS bowlers, were discriminators of playing level. As such these variables could be used as indicators of performance (i.e. performance measures) in future research.     

中国优秀女子运动员推铅球速度特征发现与分析

以１２名专项成绩在１７．３６ｍ以上采用背向滑步推铅球技术的中国优秀女子运动员为研究对象,采用高速摄影与影片解析等方法,研究分析运动员推铅球技术的身体重心与铅球速度及其关系变化特征。研究结果表明：滑步结束时铅球运动速度存在一个适宜区段;运动员最后用力发力时间是在最后用力阶段之前;全程推球中铅球速度有两个较大起伏,而不是不断加速等。研究结果有助于教练员、运动员正确认识推铅球技术。     

The influence of shaft stiffness on potential energy and puck speed during wrist and slap shots in ice hockey

The purpose of this study was to explore the relationship between hockey stick shaft stiffness and puck speed with mechanical energy considerations during stationary wrist and slap shots. Thirty left-handed pro-model composite hockey sticks, submitted by eleven hockey stick manufacturers, were subjected to a mechanical cantilever bend test to determine the shaft stiffness of each stick. Eight sticks representing the entire spectrum of stiffnesses were then used by five elite male hockey players to perform stationary wrist and slap shots in a laboratory setting. Eight infra-red high-speed digital video cameras were used to capture shaft deformation and puck speed. A second mechanical test then replicated the loading patterns applied to each stick during shooting. Force-deformation data from this test were used to determine the shaft stiffness and potential energy storage and return associated with each stick during shooting. The results of this study suggest that shaft stiffness has an influence on puck speed in wrist but not slap shots. During a wrist shot, a given player should realise higher puck speeds with a stick in which they store increased elastic potential energy in the shaft. In general, flexible sticks were found to store the most energy. However, how the athlete loads the stick has as much influence on puck speed as stick construction. Energy considerations were unable to explain changes in puck speed for the slap shot. For this type of shot it is the athlete and not the equipment influencing puck speed, but the governing mechanisms have yet to be elucidated.     

中国精英女子赛艇运动员划桨技术特点分析

目的：以国家队和赛艇优势省队运动员为测试对象，总结分析我国精英女子赛艇运动员的划桨技术特点。方法：27名运动员参与本研究，利用"BioRow Tel"系统测试五种桨频（20、24、28、32、36桨/分）下的划桨技术，测试参数包括划桨节奏、桨叶轨迹、桨力特征等。结果：拉桨时间百分比随桨频的提高显著提高；入水角、出水角和划幅在中低桨频下非常稳定，但在接近比赛桨频时显著下降；抓水打滑和出水打滑均随桨频的增加而显著增加；与桨力相关的参数对桨频的变化相对不敏感。结论：我国运动员较为注重桨叶入水和拉桨前段，表现出的技术较好，而在拉桨后段特别是桨叶出水阶段暴露出的问题比较大；临近比赛桨频时的技术同中低桨频时相比存在比较明显的下降。训练中要解决好拉桨后段和桨叶出水的问题，并注重提高运动员在比赛桨频时的划桨技术。     

Movement variability in the golf swing

Traditionally, golf biomechanics has focused upon achieving consistency in swing kinematics and kinetics, whilst variability was considered to be noise and dysfunctional. There has been a growing argument that variability is an intrinsic aspect of skilled motor performance and plays a functional role. Two types of variability are described: 'strategic shot selection' and 'movement variability'. In 'strategic shot selection', the outcome remains consistent, but the swing kinematics/kinetics (resulting in the desired ball flight) are free to vary; 'movement variability' is the changes in swing kinematics and kinetics from trial to trial when the golfer attempts to hit the same shot. These changes will emerge due to constraints of the golfer's body, the environment, and the task. Biomechanical research has focused upon aspects of technique such as elite versus non-elite kinematics, kinetics, kinematic sequencing, peak angular velocities of body segments, wrist function, ground reaction forces, and electromyography, mainly in the search for greater distance and clubhead velocity. To date very little is known about the impact of variability on this complex motor skill, and it has yet to be fully researched to determine where the trade-off between functional and detrimental variability lies when in pursuit of enhanced performance outcomes.     

Timing of triggering in relation to the cardiac cycle in nonelite rifle shooters

This study investigated the timing of the trigger pull in relation to the cardiac cycle during air rifle shooting. Electrocardiogram) was recorded from 20 male nonelite rifle shooters in two separate testing sessions. The testing was conducted at an indoor shooting range using an optoelectronic shooting system. Each participant fired a shot in the standing position at a distance of 10 m from the target. The results showed that compared to random triggering, the shooters fired more often during the phase of 10-50% of the R wave-to-R wave (R-R) interval and less often during the phase of 50-90%. With regard to performance accuracy, the participants exhibited average or above average performance, when the shot occurred in the beginning (0-50%) and in the end (70-99%) of the R-R interval. The less optimal range for the triggering was located within the 50-70% phase of the R-R interval. The length of R-R interval (i.e., heart rate) did not affect the relation of shot placement within the cardiac cycle to the accuracy of shooting performance. The present results extend previous findings by showing that in air rile shooting the optimum firing time within the cardiac cycle may be located in the systolic phase. It is argued that the systole-diastole dichotomy is not a sufficiently accurate way to investigate the effects of shot placement in the cardiac cycle. Further research is needed to examine the extent to which the relationship between the timing of triggering within the cardiac cycle and shooting performance depends a shooter's skill level.     

On using wearable tri-axial accelerometers to examine the striking phase kinematics of expert specialist drag flickers on-field

Analysing player kinematics during a match using “gold-standard” 3D video-based motion analysis techniques is a difficult prospect indeed. The development of small, wireless, wearable sensors offers the potential to reduce the challenges of measuring kinematics during match-play without hindering performance. The present study examined the viability of using wireless tri-axial accelerometers to examine whether key performance measures of drag flicks executed by expert specialist drag-flickers are predicted by the kinematics of the striking phase. Linear mixed models were used to examine whether the speed and accuracy of players’ drag flicks were predicted by the duration of stick-ball contact, and the kinematics of the lead lower limb at stick-ball contact and ball release. Results revealed that stick and lead lower limb kinematics significantly predicted shot accuracy but not shot speed. Shorter drag-time predicted more accurate flicks (p = 0.03) as did a more vertical leg at stick-ball contact (p = 0.016) and a more horizontal thigh at ball release (p = 0.001). This may indicate that there are more ways to produce fast drag flicks than accurate ones. This study illustrates that wireless tri-axial accelerometers can be used on-field to measure the effects of kinematics on key performance measures.     

Index for Volume 55 (1984)

Abstract

This study investigated the timing of the trigger pull in relation to the cardiac cycle during air rifle shooting. Electrocardiogram) was recorded from 20 male nonelite rifle shooters in two separate testing sessions. The testing was conducted at an indoor shooting range using an optoelectronic shooting system. Each participant fired a shot in the standing position at a distance of 10 m from the target. The results showed that compared to random triggering, the shooters fired more often during the phase of 10–50% of the R wave-to-R wave (R-R) interval and less often during the phase of 50–90%. With regard to performance accuracy, the participants exhibited average or above average performance, when the shot occurred in the beginning (0–50%) and in the end (70–99%) of the R-R interval. The less optimal range for the triggering was located within the 50–70% phase of the R-R interval. The length of R-R interval (i.e., heart rate) did not affect the relation of shot placement within the cardiac cycle to the accuracy of shooting performance. The present results extend previous findings by showing that in air rifle shooting the optimum firing time within the cardiac cycle may be located in the systolic phase. It is argued that the systole-diastole dichotomy is not a sufficiently accurate way to investigate the effects of shot placement in the cardiac cycle. Further research is needed to examine the extent to which the relationship between the timing of triggering within the cardiac cycle and shooting performance depends a shooter's skill level.     

Perceptual-cognitive expertise when refereeing the scrum in rugby union

Compared to sports performers, relatively little is known about how sports officials make decisions at a perceptual-cognitive level. Thus, this study examined the decision-making accuracy and gaze behaviour of rugby union referees of varying skill levels while reviewing scrum scenarios. Elite (n = 9) and trainee (n = 9) referees, as well as experienced players (n = 9), made decisions while watching ten projected scrum clips and wearing a mobile eye-tracker. Decision-making accuracy and gaze behaviour were recorded for each scrum. The elite and trainee referees made more accurate decisions than the players, and differences in gaze behavior were observed. The elite and trainee referees displayed lower search rates, spent more time fixating central-pack (i.e., front rows, binds, and contact point) and less time fixating outer-pack (e.g., second rows) and non-pack (e.g., other) locations, and exhibited lower entropy than the players. While search rate failed to predict decision-making accuracy, the time spent fixating central-, outer-, and non-pack locations, as well as entropy, were significant predictors. The findings have implications for training perceptual-cognitive skill among sports officials.     

Effect of ice hockey stick stiffness on performance

Hockey sticks have undergone a dramatic transformation from wood to aluminum to composite in just over the past 20 years. With the introduction of different materials, there has been increasing interest in how the material properties affect shot speed. This study examined the effects of stick stiffness from measured swing motion on puck speed. Stick evaluation involved a six amateur player study, quasi-static stiffness measurement, video motion analysis, and numerical simulation. The effect of stiffness on puck speed was observed to depend on shot type. For shots involving large stick loading, as occurs with a slap shot, puck speed decreased as stick stiffness increased. The trend was consistent with a constant force player model. For shots involving low stick loading, as occurs with a wrist shot, puck speed increased as stick stiffness increased. The trend was consistent with a constant displacement player model. Finite element simulation of the slap shot agreed generally with the results of the player study and was used to find an optimal loading distance (distance that the stick contacts the ice prior to the puck) to be 24 cm.     

Sprint start kinematics during competition in elite and world-class male and female sprinters

The start kinematics has been reported to differ between male and female sprinters. This study aimed to determine whether kinematic differences between the sexes are attributable to an effect of sex per se, or rather to the absolute performance level of the sprinters, quantified by the 100-m time. A total of 20 sprinters (10 M, 10 F), including world-class and elite athletes, were assessed. Start phases from the “set” position to the first two steps were analysed. Linear regression analyses showed a few significant differences between sexes when taking into account the effect of performance level: M had shorter pushing phase duration, higher horizontal velocity at block clearing, and shorter contact times of the first two steps. Conversely, the performance level affected most of the examined parameters: faster sprinters showed the centre of mass (CM) closer to the ground and a more flexed front knee in the “set” position, longer pushing phase duration, lower vertical velocity of the CM at block clearing, and longer contact times and shorter flight times in the first two steps. These findings suggest that the start kinematics is only partially affected by the sex of sprinters, whereas a bigger role is played by their performance level.     

Reliability and validity of two tests of soccer skill

Twenty-four players from the 1st/2nd (elite) and 24 players from the 3rd/4th (non-elite) university football teams were recruited to evaluate the Loughborough Soccer Passing Test (LSPT) and Loughborough Soccer Shooting Test (LSST) as tools to assess soccer skill. The LSPT requires players to complete 16 passes as quickly as possible. The LSST requires players to pass, control, and shoot the ball to targets on a full-sized goal. Participants completed two main trials each separated by at least one day. During both trials, the participants were given practice efforts before recording the mean of the next two (LSPT) or 10 (LSST) attempts as the performance score. For the LSPT, the mean time taken, added penalty time, and overall performance time were less in the elite players (elite: 43.6 s, s = 3.8; non-elite: 52.5 s, s= 7.4; P= 0.0001). For the LSST, there was no difference in the mean points scored per shot between groups (elite: 1.34, s = 0.46; non-elite: 1.28, s = 0.53). However, the elite players had higher mean shot speed (elite: 80 km h(-1), s = 4.5; non-elite: 74 km h(-1), s = 4.2; P < 0.0001) and performed each shot sequence faster (elite: 7.87 s, s= 0.29; non-elite: 8.07 s, s= 0.35; P= 0.037) than the non-elite players. Performance on both tests was more repeatable in elite players. In conclusion, the LSPT and LSST are valid and reliable protocols to assess differences in soccer skill performance.     

Kinematic differences of elite and high-performance tennis players in the cross court and down the line forehand

This study identified and compared the full body kinematics of different skill levels in the forehand groundstroke when balls were hit cross court and down the line. Forty-three three-dimensional retroreflective marker trajectories of six elite and seven high-performance players were recorded using an eight-camera 400 Hz, Vicon motion analysis system. The six highest horizontal velocity forehands with reliable kinematics of all participants were analysed for each specific situation (a total of 156 analysed shots). Significant differences (p < 0.01) and large effect sizes were observed between elite and high-performance players in linear velocity of the shoulder (2.0 vs. 1.2 m/s), angular velocity of the pelvis (295 vs. 168 degrees/s), and angular velocity of the upper trunk (453 vs. 292 degrees/s) at impact. The elite group showed a tendency towards higher racquet velocities at impact (p < 0.05). No significant differences were found in angular displacement of the racquet, hip alignment, or shoulder alignment at the completion of the backswing; nor did angular displacement vary significantly at impact. Irrespective of the group, different shoulder, hip, and racquet angles were found at impact, depending on the situation. The results should assist coaches when striving to improve their players' forehand.     

Basketball shooting strategies — the free throw,direct shot and layup

A rationale and geometric parameters for optimal basketball shooting are provided. The premise is that shots requiring the least energy are the easiest to control and thus have the greatest probability of success. The kinematics of the ball movement are modelled and simulated for the free throw, for the direct shot, and for the bank shot off the backboard (the ‘layup’). For the layup, the analysis includes the effects of friction, ball inertia, ball spin and impact restitution. The results provide a means for shot planning and for coaching to improve shooting technique. The advantage of the layup for close-in shooting is demonstrated. Results of numerical parameter studies are also presented, demonstrating the ranges of allowable shooting error for the various shots, and thus also identifying the shots with highest probability of success.     

Comparison of biomechanical characteristics between male and female elite fast bowlers

This study investigated ball release speed and performance kinematics between elite male and female cricket fast bowlers. Fifty-five kinematic parameters were collected for 20 male and 20 female elite fast bowlers. Group means were analysed statistically using an independent samples approach to identify differences. Significant differences were found between: ball release speed; run-up speed; the kinematics at back foot contact (BFC), front foot contact (FFC), and ball release (BR); and the timings between these key instants. These results indicate that the female bowlers generated less whole body linear momentum during the run-up than the males. The male bowlers also utilised a technique between BFC and FFC which more efficiently maintained linear momentum compared to the females. As a consequence of this difference in linear momentum at FFC, the females typically adopted a technique more akin to throwing where ball release speed was contributed to by both the whole body angular momentum and the large rotator muscles used to rotate the pelvis and torso segments about the longitudinal axis. This knowledge is likely to be useful in the coaching of female fast bowlers although future studies are required to understand the effects of anthropometric and strength constraints on fast bowling performance.     

Predictors of scoring accuracy: ice hockey wrist shot mechanics

The purpose of this study was to identify the stationary “wrist shot” technique (movement patterns) of the ice hockey stick that corresponds to the accuracy of puck trajectory. A total of 25 subjects participated in this study, ranging from high to low caliber players. Each performed ten successful wrist shots at four targets (two top corners, two bottom corners). Performances were evaluated by recording the movements of the stick’s shaft and blade and of the puck with a 3D motion capture system at 240 Hz. Kinematics of the shaft and blade of the hockey stick were examined using a multiple regression analysis to predict accuracy scores. In general, the results indicated that accuracy corresponded to release parameters (both puck release orientation and velocity), shaft bending and change in blade orientations; though, parameter weighting differed substantially for top versus bottom targets. Future studies are warranted to identify the whole body kinematic patterns associated with the hockey stick kinematics.     

背向滑步推铅球的衔接技术

衔接技术是铅球投掷技术的重要环节，是沟通滑步技术与最后用力技术的关键。恰当地把握这一项技术环节是完整推铅球技术的核心。衔接技术又叫过渡步技术，近几年来，对优秀运动员推铅球的衔接技术有适当的分析。本文在前人实验的基础上，对衔接技术进行综合分析，目的在于正确阐明衔接技术的要领，衔接技术与滑步技术、预行速度、重心移动轨迹等之间存在的关系，从而使整体技术更加符合运动技术原理，利于提高运动成绩。