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1.
A cross-sectional study was conducted to investigate developmental characteristics within six body component actions for the overhead serve in tennis and to determine if such actions should be validated through longitudinal study. Developmental sequences, hypothesized for two components during the preparatory phase and four components during the force production phase of the overhead tennis serve, were used to classify the videotaped serving actions of 30 male and 30 female tennis players. Sequences hypothesized for the Preparatory Trunk, Elbow, and Forearm/Racket actions met the prelongitudinal screening criteria proposed by Roberton (1978); Roberton, Williams, and Langendorfer (1980); and Langendorfer (1982). Sequences for these component actions should be validated through longitudinal study. Steps within sequences for the Preparatory Backswing, Trunk for Force, and Feet/Legs are apparently misordered or not characteristic of a developmental process. Further cross-sectional study of these component actions prior to longitudinal study is recommended.  相似文献   

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Abstract

A cross-sectional study was conducted to investigate developmental characteristics within six body component actions for the overhead serve in tennis and to determine if such actions should be validated through longitudinal study. Developmental sequences, hypothesized for two components during the preparatory phase and four components during the force production phase of the overhead tennis serve, were used to classify the videotaped serving actions of 30 male and 30 female tennis players. Sequences hypothesized for the Preparatory Trunk, Elbow, and Forearm/Racket actions met the prelongitudinal screening criteria proposed by Roberton (1978); Roberton, Williams, and Langendorfer (1980); and Langendorfer (1982). Sequences for these component actions should be validated through longitudinal study. Steps within sequences for the Preparatory Backswing, Trunk for Force, and Feet/Legs are apparently misordered or not characteristic of a developmental process. Further cross-sectional study of these component actions prior to longitudinal study is recommended.  相似文献   

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The purpose of this study was to compare ball skill performance of children with and without DCD in a one-on-one testing situation. A sample of 107 children (48 girls and 59 boys) aged between 7 and 11 years was recruited for this project. In total, 45 (42.1%) met the criteria for DCD, and 62 (57.9%) did not. Motor ability was assessed using the Movement Assessment Battery (M-ABC). Each participant was required to complete ten overhand throws and to catch a ball adjusted to their hand size ten times. Video analysis was used to determine the developmental level of throwing and catching. Analyses of covariance (ANCOVA) revealed a significant main effect of DCD for all developmental sequences of catching (p<0.05), for the number of catches (p<0.001) and for the accuracy of the throws (p<0.001). Furthermore, the data revealed that children with DCD displayed less advanced modal developmental sequence levels than normally developing children for throwing with respect to the arm action (p<0.05), the backswing (p<0.10) and the foot action (p<0.05). The findings from this study clearly showed that children with DCD are at a disadvantage in controlling a ball. Without a tailored intervention these children will not be able to participate properly in physical activities.  相似文献   

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Background: Valid motor development sequences show the various behaviors that children display as they progress toward competence in specific motor skills. Teachers can use these sequences to observe informally or formally assess their students. While longitudinal study is ultimately required to validate developmental sequences, there are earlier, pre-longitudinal steps that can be used to screen hypothesized sequences to see if they are worthy of the time and expense of longitudinal study. These same steps can also provide teachers with preliminary tools for observation/assessment. Purpose: At the request of physical educators in a midwestern suburb in the United States, the investigators screened developmental sequences for the action of arms and legs in self-turned rope jumping. The goal was to create a preliminary assessment tool that could be used in physical education classes. Participants: The physical educators took videos of 216 children attempting to jump rope. The children were 5–10 years of age. Data analysis: The investigators categorized the videos using the hypothesized developmental sequences as a checklist. The incidence of each level in the sequences was then graphed to see if the percentages of occurrence rose and fell across age as would be expected if the levels were developmentally valid. The investigators also looked at whether children who varied their behavior across trials varied only to adjacent levels in the sequences. Results: Results indicated that one hypothesized arm category was not developmental, and two leg categories needed further study in younger children. Based on these results, the investigators modified the proposed sequences and provided decision rules so teachers could use them as preliminary observation/assessment tools.  相似文献   

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The purposes of this study were to: (a) examine differences within specific kinematic variables and ball velocity associated with developmental component levels of step and trunk action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Results indicated stride length (69.3 %) and time from stride foot contact to ball release (39. 7%) provided substantial contributions to ball velocity (p < .001). All trunk kinematic measures increased significantly with increasing component levels (p < .001). Results suggest that trunk linear and rotational velocities, degree of trunk tilt, time from stride foot contact to ball release, and ball velocity represented potential control parameters and, therefore, constraints on overarm throwing acquisition.  相似文献   

10.
Halverson, Roberton, and Langendorfer (1982) reported the development of children ages 6-13 years filmed longitudinally performing the forceful overarm throw. These authors described the children's progress through developmental sequences for trunk, humerus, and forearm actions; however, they did not study developmental relationships ("profiles") across these components. This paper reports how the profiles changed in the same children across trials within filming sessions and over time. The data revealed both common and individual developmental pathways. The frequencies of some pathways were not chance occurrences (p < or = .01), suggesting that within-person constraints eliminated certain movement relationships while encouraging others. The authors hypothesize that the kinematics of trunk rotation may serve as a control parameter for pattern change.  相似文献   

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The purposes of this study were to: (a) examine the differences within 11 specific kinematic variables and an outcome measure (ball velocity) associated with component developmental levels of humerus and forearm action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Significant differences among component levels in five of six humerus kinematic variables (p <.01) and all five forearm kinematic variables (p < .01) were identified using multivariate analysis of variance. These kinematic variables represent potential control parameters and, therefore, constraints on overarm throwing acquisition.  相似文献   

13.
The purposes of this study were to: (a) examine differences within specific kinematic variables and ball velocity associated with developmental component levels of step and trunk action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Results indicated stride length (69.3%) and time from stride foot contact to ball release (39.7%) provided substantial contributions to ball velocity (p < .001). All trunk kinematic measures increased significantly with increasing component levels (p < .001). Results suggest that trunk linear and rotational velocities, degree of trunk tilt, time from stride foot contact to ball release, and ball velocity represented potential control parameters and, therefore, constraints on overarm throwing acquisition.  相似文献   

14.
The importance of effector visual feedback has previously been indicated using an opaque screen to prevent sight of the catching hand for the final 150–200 ms of a flight path of 850 ms in total. Attention was drawn to the finding that the ability to position the arm correctly in the line of flight of the ball deteriorated as a consequence of the number of trials without visual feedback. However, the use of only 20 test trials allows a possibility that the proprioceptive system may be able to re‐establish predominant control under conditions of prolonged visual decrement. In order to verify this notion, the number of experimental trials was quadrupled for 24 subjects of mixed sex in a replication of the initial paradigm.

The results provided preliminary support for the view that the positioning of the catching arm is more seriously affected by visual occlusion than the timing of the grasp phase. However, increments in accuracy of limb orientation were evidenced in all screen conditions, as the number of trials increased. The grasp component of one‐handed catching appeared to remain unaffected by the increase in experimental trials. The relative influence of skill level on catching errors was next addressed by comparing the performance of the six best and worst catchers in the group.

The results did not support previous research which found a relation between skill level and error type. The number of position, but not grasp, errors decreased as a function of task practice for both subgroups. Future investigations should, perhaps, focus on the developmental nature of movement control in one‐handed catching to obtain a clearer picture of this relation.  相似文献   

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Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21±2 years, height 1.83±0.1?m, body mass 85.3±12?kg, body fat 14?±?5%; mean±s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20?m without the ball (2.58±0.16?s), using both hands (2.62±0.16?s) led to a significantly slower time (P?<0.05). Sprinting 20?m with the ball under the left arm (2.61±0.15?s) or under the right arm (2.60± 0.17?s) was significantly quicker than when using ‘both hands’ (P?<0.05), and both these methods were significantly slower than when running without the ball (P?<0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm.  相似文献   

17.
The purposes of this study were to: (a) examine the differences within 11 specific kinematic variables and an outcome measure (ball velocity) associated with component developmental levels of humerus and forearm action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Significant differences among component levels in five of six humerus kinematic variables (p < .01) and all five forearm kinematic variables (p < .01) were identified using multivariate analysis of variance. These kinematic variables represent potential control parameters and, therefore, constraints on overarm throwing acquisition.  相似文献   

18.
Peripheral vision and simple catching: the screen paradigm revisited   总被引:1,自引:0,他引:1  
The importance of effector visual feedback has previously been indicated using an opaque screen to prevent sight of the catching hand for the final 150-200 ms of a flight path of 850 ms in total. Attention was drawn to the finding that the ability to position the arm correctly in the line of flight of the ball deteriorated as a consequence of the number of trials without visual feedback. However, the use of only 20 test trials allows a possibility that the proprioceptive system may be able to re-establish predominant control under conditions of prolonged visual decrement. In order to verify this notion, the number of experimental trials was quadrupled for 24 subjects of mixed sex in a replication of the initial paradigm. The results provided preliminary support for the view that the positioning of the catching arm is more seriously affected by visual occlusion than the timing of the grasp phase. However, increments in accuracy of limb orientation were evidenced in all screen conditions, as the number of trials increased. The grasp component of one-handed catching appeared to remain unaffected by the increase in experimental trials. The relative influence of skill level on catching errors was next addressed by comparing the performance of the six best and worst catchers in the group. The results did not support previous research which found a relation between skill level and error type. The number of position, but not grasp, errors decreased as a function of task practice for both subgroups. Future investigations should, perhaps, focus on the developmental nature of movement control in one-handed catching to obtain a clearer picture of this relation.  相似文献   

19.
Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21 +/- 2 years, height 1.83 +/- 0.1 m, body mass 85.3 +/- 12 kg, body fat 14 +/- 5%; mean +/- s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20 m without the ball (2.58 +/- 0.16 s), using both hands (2.62 +/- 0.16 s) led to a significantly slower time (P < 0.05). Sprinting 20 m with the ball under the left arm (2.61 +/- 0.15 s) or under the right arm (2.60 +/- 0.17 s) was significantly quicker than when using 'both hands' (P < 0.05), and both these methods were significantly slower than when running without the ball (P < 0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm.  相似文献   

20.
Background:Gross motor skills are postulated to have a bidirectional relationship with physical activity(PA);however,no study has tested this relationship before and after a summer break.The purpose of this study was to examine the bidirectional relationships between school PA and gross motor skills in children before and after a summer break.Methods:Participants were a sample of 440 children recruited from 3 low-income schools(age=8.9±1.2 years,mean±SD).PA was assessed as average school-day step counts using Yamax DigiWalker pedometers(Yamasa Tokei Keiki,Tokyo,Japan)worn for 5 consecutive school days.Gross motor skills were assessed using the Test for Gross Motor Development,3 rd edition.Data were collected at 2 timepoints:at the end of spring semester(T1)and at the beginning of the subsequent fall semester(T2).An age-and body mass index-adjusted cross-lagged model was employed to relate T1 school step counts with T2 gross motor skills and T1 gross motor skills with T2 school step counts.Results:T1 gross motor skills significantly predicted T2 school step counts(β=0.24,95%confidence interval(95%CI):0.08-0.40,p=0.003);however,Tl school step counts did not predict T2 gross motor skills(β=0.04,95%CI:-0.06 to 0.14,p=0.445).The model explained 35.4%and 15.9%of the variances of T2 gross motor skills and T2 school step counts,respectively.Additional analyses indicated that these relationships were driven primarily by ball skills.Conclusion:The relationship between gross motor skills and school PA was not bidirectional;however,higher gross motor skills,specifically ball skills,predicted higher school PA after a 3-month summer break.  相似文献   

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