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1.
The influence of a bowling harness, as a training aid, was assessed as a means of modifying bowling technique. Thirty-three 13-year-old bowlers received a standardized 15 min of bowling coaching twice a week for 8 weeks. They were randomly assigned to one of two groups. The 13 participants in the intervention group used the bowling harness throughout the coaching, while also receiving verbal and visual feedback. The 20 participants in the non-harness group received the same visual and verbal feedback. Three-dimensional videography (200 Hz) of each player's bowling action enabled the calculation of transverse plane shoulder alignment counter-rotation, separation angle, lateral flexion and hyperextension of the trunk before and after the intervention. The restriction applied by the harness produced a significant reduction (P= 0.006) in separation angle and forced the bowler to adopt a position at back-foot impact that reduced the 'twist' in the spine. However, it had no effect on restricting other aspects of trunk movement during the critical phases of the bowling action. No significant long-term modifications to technique were found after the coaching intervention when players were assessed without the harness.  相似文献   

2.
Fast bowling in cricket is an activity that is well recognised as having high injury prevalence and there has been debate regarding the most effective fast bowling technique. The aim of this study was to determine whether two-year coaching interventions conducted in a group of elite young fast bowlers resulted in fast bowling technique alteration. Selected kinematics of the bowling action of 14 elite young fast bowlers were measured using an 18 camera Vicon Motion Analysis system before and after two-year coaching interventions that addressed specific elements of fast bowling technique. Mann-Whitney tests were used to determine whether any changes in kinematic variables occurred pre- and post-intervention between those who had the coaching interventions and those who didn't. The coaching interventions, when applied, resulted in a more side-on shoulder alignment at back foot contact (BFC) (p = 0.002) and decreased shoulder counter-rotation (p = 0.001) however, there was no difference in the degree of change in back and front knee flexion angles or lower trunk side-flexion. This study has clearly shown that specific aspects of fast bowling technique are changeable over a two-year period in elite level fast bowlers and this may be attributed to coaching intervention.  相似文献   

3.

This study tested a computer‐aided coaching analysis instrument (CAI) as part of an intervention strategy designed to modify verbal coaching behaviour. Four coaches were observed and analysed over 12 practice sessions. Coaches A, B and C received intervention feedback through CAI data, where selected behaviours were highlighted for discussion, and videotape images were used to illustrate discussion points. Coach D was provided with videotapes of his own performance and told to formulate and implement any of his own recommendations. The CAI data are primarily quantitative, so target values were created for the different dimensions of verbal behaviour. This benefited the coaches in interpreting their effectiveness and provided a reference to evaluate the magnitude of change. Written journals and audiotape recordings were also used to promote insight into the complexity of verbal behaviour and the ‘human factors’ (e.g. relationship with players, attitude to researcher) that affect behaviour modification.

Instructional effectiveness was assessed by time‐series analysis. There was evidence from each behaviour dimension that change can occur and be maintained as a result of exposure to the CAI intervention strategy. However, this is clearly contingent upon the coach understanding what is asked of him or her, and remains focused and committed to changing these particular behaviours. The analysis of Coach D's behavioural change suggests there are limitations to the sensitivity of discretionary viewing, as only two dimensions of behaviour were identified for, and resulted in, positive change. The results of this study provide support for Locke's (1984) contention that behaviour modification can occur by using data as direct feedback, as reinforcement and as information in the form of recommendations. However, the study also illuminates several factors that can negate the modification and maintenance of verbal coaching behaviour.  相似文献   

4.
We examined whether altering the amount of and moment when visual information is presented affected observational learning for participants practicing a bowling skill. On Day 1, four groups practiced a cricket bowling action. Three groups viewed a full-body point-light model, the model's bowling arm, or between-limb coordination of the model's left and right wrists only. Following retention tests on Day 2, all participants practiced after viewing a full-body display. Retention was again tested on Day 3. Bowling accuracy improved in all four practice groups. Kinematics of the bowling arm became more like the model for the full-body and intralimb groups only. All groups improved on measures of interlimb coordination. Visual search data indicated that participants mainly focused their gaze on the model's bowling arm. These data lead to the suggestion that viewing “end-effector” information (i.e., information pertaining to the bowling arm) is an important perceptual constraint early in observational learning. Implicit manipulations designed to increase attention to other sources of information did not facilitate the learning process.  相似文献   

5.
Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.  相似文献   

6.
The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty‐two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20‐min treadmill running sessions over a 5‐week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High‐speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P < 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non‐support. There were no significant differences between the groups in submaximal VO2 or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.  相似文献   

7.
The aim of this study was to assess the effect of pitch length (20.12 m [full length], 18 m and 16 m) on the fast bowling performance and technique of junior cricketers. Performance measures included ball release speed and accuracy, while technique variables evaluated were those shown to be related to the aetiology of lower back injury. Thirty-seven fast bowlers from the under-11 (n=14), under-13 (n=11) and under-15 (n=12) age groups were filmed bowling five deliveries at each of the above pitch lengths. Two synchronized NAC video cameras operating at 200 Hz permitted three-dimensional reconstruction of the hip and shoulder alignments, while a standard digital video camera operating at 50 Hz (positioned perpendicular to the bowling action) was used to measure front knee angle and ball release speed. Accuracy scores were taken from a zoned target at the batsman's stumps. A two-way analysis of variance with repeated measures (with age and pitch length as the between- and within-participant variables, respectively) was used to compare each age group at the 0.05 significance level. Results showed that accuracy improved in all age groups at shorter pitch lengths, although ball velocity remained constant throughout all trials. Shoulder counter-rotation increased significantly for the under-13 bowlers when bowling on the full-length pitch in comparison with the two shorter lengths. Counter-rotation also increased on the full-length pitch in the under-11 age group, although this increase was not significant. The under-15 bowlers' techniques did not change as pitch length increased. As under-11 and under-13 bowlers adopted a "safer" bowling action with superior accuracy on the 18?m compared with the full length pitch, it was concluded that these age groups should bowl on an 18?m pitch to reduce the likelihood of lower back injuries and improve accuracy.  相似文献   

8.
Lower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aims of this study were to quantify the proportion of lower trunk motion used during the delivery stride of fast bowling and to examine the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. A high percentage of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30 degrees. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (129%), and ipsilateral rotation (79%) was used during the front foot contact phase of the fast bowling delivery stride. There was no significant difference in the proportions of available lower trunk extension, contralateral side-flexion, and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. Motion of the lower trunk, particularly side-flexion, during front foot contact, in addition to variables previously known to be related to back injury (e.g. shoulder counter-rotation), should be examined in future cross-sectional and prospective studies examining the fast bowling action and low back injury.  相似文献   

9.
Abstract

Lower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aims of this study were to quantify the proportion of lower trunk motion used during the delivery stride of fast bowling and to examine the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. A high percentage of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30°. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (129%), and ipsilateral rotation (79%) was used during the front foot contact phase of the fast bowling delivery stride. There was no significant difference in the proportions of available lower trunk extension, contralateral side-flexion, and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. Motion of the lower trunk, particularly side-flexion, during front foot contact, in addition to variables previously known to be related to back injury (e.g. shoulder counter-rotation), should be examined in future cross-sectional and prospective studies examining the fast bowling action and low back injury.  相似文献   

10.
We assessed the effects on basketball free throw performance of two types of verbal directions with an external attentional focus. Novices ( n = 16) were pre-tested on free throw performance and assigned to two groups of similar ability ( n = 8 in each). Both groups received verbal instructions with an external focus on either movement dynamics (movement form) or movement effects (e.g. ball trajectory relative to basket). The participants also observed a skilled model performing the task on either a small or large screen monitor, to ascertain the effects of visual presentation mode on task performance. After observation of six videotaped trials, all participants were given a post-test. Visual search patterns were monitored during observation and cross-referenced with performance on the pre- and post-test. Group effects were noted for verbal instructions and image size on visual search strategies and free throw performance. The 'movement effects' group saw a significant improvement in outcome scores between the pre-test and post-test. These results supported evidence that this group spent more viewing time on information outside the body than the 'movement dynamics' group. Image size affected both groups equally with more fixations of shorter duration when viewing the small screen. The results support the benefits of instructions when observing a model with an external focus on movement effects, not dynamics.  相似文献   

11.
In Experiment 1, adult and child participants were instructed to imitate a video model performing a bowling action with or without a ball. Participants imitated the action with greater accuracy without a ball and in general adults were more accurate than children. In Experiment 2, adults and children were shown a video or point-light display of the bowling action. There was no difference in movement form between the adult point-light and video groups. In contrast, children were poorer at reproducing the action when viewing point-light compared with video sequences (P < 0.05). The novel point-light display hindered the children's ability to provide conceptual mediation between the presented information and action requirements. In Experiment 3, a child point-light group was provided with perceptual-cognitive training. The perceptual-cognitive training group demonstrated better movement reproduction than a group who viewed the point-light displays with no training (P < 0.05), although there were no differences between participants who received training and those who viewed a video. Children are able to perceive and use relative motion information from a display after some general training, and the effectiveness of demonstrations needs to be judged relative to the task context.  相似文献   

12.
The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty-two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20-min treadmill running sessions over a 5-week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High-speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P less than 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non-support. There were no significant differences between the groups in submaximal VO2 or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.  相似文献   

13.
ABSTRACT

Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase.  相似文献   

14.
ABSTRACT

When executed correctly, swing bowling has the potential to influence the outcome of a cricket match, yet little is known about the required bowling action and ball flight characteristics. This study aimed to describe the bowling action and initial ball flight characteristics as well as to identify variables that may be associated with increased swing in pathway and high-performance medium and fast pace bowlers. A 17-camera Vicon motion analysis system captured retro-reflective markers placed on the upper-body of participants and new cricket balls to quantify bowling action and initial ball flight kinematics. Bowlers delivered the ball with their forearm and hand angled in the direction of intended swing with an extended wrist flexing through the point of ball release. Bowlers who produced more swing had increased seam stability, possibly linked to a lower wrist and ball angular velocity. It is believed that swing increases with seam stability, however, optimal ranges may exist for seam azimuth angle, ball angular velocity and release speed. These findings may assist coaches to optimise the performance of bowlers, however, future research should use bowlers who play at higher levels to investigate swing bowling at greater speeds.  相似文献   

15.
Comparison of modes of feedback on glide performance in swimming   总被引：1，自引：1，他引：0  
The software product "GlideCoach" was recently developed to give quantitative and qualitative feedback on the glide performance of a swimmer (Naemi & Sanders, 2008 ). This study compared the effect of feedback on glide performance from GlideCoach with video and verbal feedback. Nineteen elite swimmers were randomly assigned to one of three groups: Group 1 and 2 included six swimmers and Group 3 included seven swimmers. All participants performed ten dives in each of five sessions. Each group received one of three forms of feedback (video, video and verbal, and GlideCoach and verbal) for four sessions. In the fifth, retest session, performed 4 weeks after the fourth session, all groups received GlideCoach and verbal feedback only. This enabled the analysis of GlideCoach and verbal feedback on performance of the groups that had not yet received this feedback and assessment of the retention ability for the group that had. Feedback resulted in all groups recording an improvement, as indicated by effect sizes, for average velocity, glide factor (related to resistive drag), and initial velocity (P < 0.05). The improvement following the GlideCoach and verbal feedback was greater than that of the two other feedback methods for all variables of interest (P < 0.05), with effect sizes ranging from 1.0 to 2.5, compared with values less than 0.6 for the other feedback methods. We conclude that GlideCoach feedback is effective in improving glide performance.  相似文献   

16.
In this study a method for determining elbow extension and elbow abduction for a cricket bowling delivery was developed and assessed for Jenny Gunn who has hypermobility in both elbows and whose bowling action has been repeatedly queried by umpires. Bowling is a dynamic activity which is assessed visually in real time in a cricket match by an umpire. When the legality of a bowler's action is questioned by an umpire a quantitative analysis is undertaken using a marker based motion analysis system. This method of quantifying elbow extension should agree with a visual assessment of when the arm is "straight" and should minimise the effects of marker movement. A set of six markers on the bowling arm were used to calculate elbow angles. Differences of up to 1° for elbow extension and up to 2° for elbow abduction were found when angles calculated from the marker set for static straight arm trials were compared with measurements taken by a chartered sports physiotherapist. In addition comparison of elbow extension angles at ball release calculated from the markers during bowling trials with those measured from high speed video also showed good agreement with mean differences of 0°±2°.  相似文献   

17.
The purpose of this study was to discover the contributions of individual upper body segmental rotations to ball release speed for cricket bowling and determine whether attempting to forcefully flex the lower trunk leads to an increase in ball release speed and bowling accuracy. Three dimensional kinematic data of eight male fast bowlers were recorded by a Vicon motion capture system under three cricket bowling conditions: (1) participants bowled at their stock delivery speeds (sub-max condition), (2) participants bowled at their absolute maximal speeds (max condition), and (3) participants bowled at their absolute maximal speeds but forced to flex the lower trunk (max-trunk condition). The accuracy of each delivery was also measured. The results showed that the average ball release speeds for the max-trunk condition were faster than the other two conditions. A general pattern of proximal to distal sequencing was observed for all three conditions. There was a slight decrement in accuracy seen in the max-trunk condition with respect to the other two conditions. For all three conditions, the upper arm rotation made the largest contribution, followed in turn by torso and thorax rotation, pelvis rotation, linear velocity of pelvis, and forearm and hand rotation.  相似文献   

18.
We assessed the effects on basketball free throw performance of two types of verbal directions with an external attentional focus. Novices (n = 16) were pre-tested on free throw performance and assigned to two groups of similar ability (n = 8 in each). Both groups received verbal instructions with an external focus on either movement dynamics (movement form) or movement effects (e.g. ball trajectory relative to basket). The participants also observed a skilled model performing the task on either a small or large screen monitor, to ascertain the effects of visual presentation mode on task performance. After observation of six videotaped trials, all participants were given a post-test. Visual search patterns were monitored during observation and cross-referenced with performance on the pre- and post-test. Group effects were noted for verbal instructions and image size on visual search strategies and free throw performance. The 'movement effects' group saw a significant improvement in outcome scores between the pre-test and post-test. These results supported evidence that this group spent more viewing time on information outside the body than the 'movement dynamics' group. Image size affected both groups equally with more fixations of shorter duration when viewing the small screen. The results support the benefits of instructions when observing a model with an external focus on movement effects, not dynamics.  相似文献   

19.
The objective of the study was to evaluate two types of cricket bowling techniques by comparing the lumbar spinal loading using a musculoskeletal modelling approach. Three-dimensional kinematic data were recorded by a Vicon motion capture system under two cricket bowling conditions: (1) participants bowled at their absolute maximal speeds (max condition), and (2) participants bowled at their absolute maximal speeds while simultaneously forcing their navel down towards their thighs starting just prior to ball release (max-trunk condition). A three-dimensional musculoskeletal model comprised of the pelvis, sacrum, lumbar vertebrae and torso segments, which enabled the motion of the individual lumbar vertebrae in the sagittal, frontal and coronal planes to be actuated by 210 muscle-tendon units, was used to simulate spinal loading based on the recorded kinematic data. The maximal lumbar spine compressive force is 4.89 ± 0.88BW for the max condition and 4.58 ± 0.54BW for the max-trunk condition. Results showed that there was no significant difference between the two techniques in trunk moments and lumbar spine forces. This indicates that the max-trunk technique may not increase lower back injury risks. The method proposed in this study could be served as a tool to evaluate lower back injury risks for cricket bowling as well as other throwing activities.  相似文献   

20.
Bowlers in cricket try to disguise their bowling action by movement pattern similarity. The batter's task is, therefore, to solve rapidly perceptual discrimination problems. Previous research has suggested that batters can discriminate perceptual cues that provide depth or target information. However, at present, there is a lack of applied research evidence on further perceptual cue utilization, including bowling delivery identification. This ability is required when batting against wrist-spin bowlers who may use five different types of delivery. In the present study, we assessed this perceptual discrimination ability among three distinct standards of batters. In addition, the relative potency of body action and ball flight information was assessed by visual occlusion techniques. We found that more expert batters in general showed greater perceptual discrimination skills when faced with different ball types. However, this discrimination ability was linked specifically to delivery type and to previous experience. We also found that additional ball flight information provided no more advantage to this discrimination ability. This finding reinforces the importance of advanced cue information and the need to expose cricket batters to different bowling actions. Further study of the development of movement pattern recognition is recommended.  相似文献   

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