A three-dimensional kinematic analysis of the long jump take-off

The long jump has been widely studied in recent years. Two models exist in the literature which define the relationship between selected variables that affect performance. Both models suggest that the critical phase of the long jump event is the touch-down to take-off phase, as it is in this phase that the necessary vertical velocity is generated. Many three dimensional studies of the long jump exist, but the only studies to have reported detailed data on this phase were two-dimensional in nature. In these, the poor relationships obtained between key variables and performance led to the suggestion that there may be some relevant information in data in the third dimension. The aims of this study were to conduct a three-dimensional analysis of the touch-down to take-off phase in the long jump and to explore the interrelationships between key variables. Fourteen male long jumpers were filmed using three-dimensional methods during the finals of the 1994 (n = 8) and 1995 (n = 6) UK National Championships. Various key variables for the long jump were used in a series of correlational and multiple regression analyses. The relationships between key variables when correlated directly one-to-one were generally poor. However, when analysed using a multiple regression approach, a series of variables was identified which supported the general principles outlined in the two models. These variables could be interpreted in terms of speed, technique and strength. We concluded that in the long jump, variables that are important to performance are interdependent and can only be identified by using appropriate statistical techniques. This has implications for a better understanding of the long jump event and it is likely that this finding can be generalized to other technical sports skills.     

Changing students' attitudes towards risky motor tasks: An application of the IZOF model

The aim of this study was to evaluate the effectiveness of an intervention programme in the physical education setting designed to change attitudes and emotions triggered by potentially risky motor tasks. The individual zones of optimal functioning (IZOF) model was used as a theoretical framework for the study. Italian male and female high school students (N = 84) took part in a 12 lesson intervention and in test?–?retest sessions. The assessment was conducted using the Motor Activity Anxiety Test to measure the students' approach-avoidance attitudes in the face of physical education tasks purported to engender strong emotional reactions. An idiosyncratic emotional profile was also implemented using a list of pleasant/unpleasant emotional adjectives. Two experimental groups were involved in the learning and performing of several potentially risky, highly emotion-arousing tasks, while two control groups were engaged in low-risk team sports. According to the hypothesis of the study, the programme was effective in decreasing the students' avoidance tendencies towards thrilling tasks and in increasing optimal?–?pleasant emotions. Our findings also demonstrated the feasibility and utility of applying the IZOF model to the context of physical education.     

Segmental dynamics of soccer instep kicking with the preferred and non-preferred leg

Abstract

Detailed time-series of the resultant joint moments and segmental interactions during soccer instep kicking were compared between the preferred and non-preferred kicking leg. The kicking motions of both legs were captured for five highly skilled players using a three-dimensional cinematographic technique at 200 Hz. The resultant joint moment (muscle moment) and moment due to segmental interactions (interaction moment) were computed using a two-link kinetic chain model composed of the thigh and lower leg (including shank and foot). The mechanical functioning of the muscle and interaction moments during kicking were clearly illustrated. Significantly greater ball velocity (32.1 vs. 27.1 m · s^?1), shank angular velocity (39.4 vs. 31.8 rad · s^?1) and final foot velocity (22.7 vs. 19.6 m · s^?1) were observed for the preferred leg. The preferred leg showed a significantly greater knee muscle moment (129.9 N · m) than the non-preferred leg (93.5 N · m), while no substantial differences were found for the interaction moment between the two legs (79.3 vs. 55.7 N · m). These results indicate that the highly skilled soccer players achieved a well-coordinated inter-segmental motion for both the preferred and non-preferred leg. The faster leg swing observed for the preferred leg was most likely the result of the larger muscle moment.     

Changes in the perception of action possibilities while climbing to fatigue on a climbing wall

Abstract

In two experiments we examined changes in the perception of action possibilities as a function of exertion. In Experiment 1, participants repeatedly climbed on a climbing wall in a series of trials that progressively increased in number to 10 trials, resulting in increased exertion. Before and during climbing, the participants judged their maximum reaching height and perceived exertion. On a separate day, participants climbed another 10 trials while performing actual maximum reaches. Higher perceived exertion was associated with decreases in perceived maximum reach while the actual reaches did not decrease. However, the perceptual changes occurred early during task execution when the participants were not yet fatigued. When exertion set in, neither perceived nor actual maximum reaching appeared to be affected. In Experiment 2, we included exhaustion trials. The findings replicated the early changes in perception observed in Experiment 1, which may be explained by hands-on experience with the task. Furthermore, while climbing to exhaustion, perceptual judgements largely changed in keeping with changes in the actual maximum reach. Thus, there appeared to be a functional relationship between participants' actual action capabilities, rather than their state of physical fatigue per se, and perceived action possibilities.     

Activity profile of top-class association football referees in relation to performance in selected physical tests

Abstract

The aims of the present study were (1) to analyse the physical demands of top-class referees and (2) to compare their official FIFA fitness test results with physical performance during a match. The work rate profiles of 11 international referees were assessed during 12 competitive matches at the 2003 FIFA Under-17 World Cup and then analysed using a bi-dimensional photogrammetric video analysis system based on direct lineal transformation (DLT) algorithms. In the first 15 min of matches, the referees were more active, performing more high-intensity exercise (P < 0.01) than in the first 15 min of the second half. During the second half of matches, the referees covered a shorter distance (P < 0.01), spent more time standing still (P < 0.05), and covered less ground cruising (P < 0.05), sprinting (P < 0.05), and moving backwards (P < 0.001) than in the first half. Also in the second 45 min, the distance of referees from infringements increased (P < 0.05) in the left attacking zone of the filed. There was also a decrease (P < 0.05) in performance in the period following the most high-intensity activity, compared with the mean for the 90 min. Time spent performing high-intensity activities during a match was not related to performance in the 12-min run (r ² = 0.30; P < 0.05), the 200-m sprint (r ² = 0.05; P < 0.05), or the 50-m sprint (r ² = 0.001; P < 0.05). The results of this study show that: (1) top-class referees experienced fatigue at different stages of the match, and (2) the typical field tests used by FIFA (two 50-m and 200-m sprints, followed by a 12-min run) are not correlated with match activities.     

日本终身学习体系构建的保障及其启示

上世纪70年代左右,终身教育和终身学习理念的相继提出给世界各国发展教育提供了新的视野。日本终身教育在四十多年发展过程中积累了丰富的理论和实践经验,走在了亚洲甚至是世界的前列。因此,探讨日本终身学习体系构建的保障,从法律法规体系、机构设施体系和财政投入体系三方面进行解析,对我国构建和发展终身教育有借鉴作用。     

Effects of Method of Subject Selection (Volunteer vs Random) and Treatment Variable on Motor Performance

Abstract

The purpose of this study was to test for possible interaction effects between method of subject selection (volunteer vs random) and a selected treatment variable—verbal encouragement. The presence of such an interaction would suggest that generalizations regarding verbal encouragement could be made only to specific subject populations. Volunteer (n = 40) and randomly selected (n = 40) subjects were randomly assigned to either a verbal encouragement condition or to a control group with no verbal encouragement. Dependent variables were a tapping task and a leg lift task. It was predicted that volunteer subjects, due to their higher need for approval and greater desire to accommodate, would perform significantly better under the verbal encouragement condition than would the randomly selected subjects. Multivariate and univariate data analyses indicated that the prediction was supported on the tapping task (female subjects only) but not on the leg lift task. It was concluded, at least on certain tasks, that use of volunteer subjects may result in a selection bias × treatment interaction effect that could limit the generalizability of research results.     

A Test of Schmidt's Schema Theory of Discrete Motor Skill Learning

Abstract

Schmidt's (1975) schema theory was tested with subjects who had to emit a rapid aiming response while wearing prism glasses. The glasses enabled them to view the target, but not their responding limb or the outcome of the movement. The problem was to determine the effect of (a) training with variable target practice, and (b) experiencing visual displacement information of the target, prior to training, on performance in transfer to a novel target distance. A 2 × 2 (type of practice × displacement information) factorial design was used, in which four groups of 15 male college subjects performed 60 training trials with verbal knowledge of results. The groups with variable target practice had less error on initial transfer to the novel target and throughout transfer than the groups with nonvariable target practice. No evidence was found to indicate that rate of learning for a novel target distance during transfer in the absence of KR is a positive function of the variability of target practice in training. Nor was any effect found for experiencing visual displacement information on performance in transfer.     

Trends in the Selection of Coaches for Female Athletes: A Demographic Inquiry

Abstract

Data were collected from 335 collegiate female athletic directors utilizing a questionnaire designed to assess trends in selecting coaches for female athletes between 1974 and 1979. These demographic results revealed: (a) a 37% increase in the number of coaches for female athletes, (b) a greater increase at the assistant (229%) rather than head (8%) coach level, (c) a substantial increase in male coaches (724) in comparison to their female counterparts (44), (d) a significant decline (294) in female head coaches, and (e) a large increase in the number of male head coaches (437). As the bases for this present investigation, current practices and affirmative action strategies were discussed (i.e., gender employment trends, de facto discrimination, federal civil rights legislation). Possible explanations of these findings were offered.