Human kinematics and event control: on-line movement registration as a means for experimental manipulation

In human movement and sports science, manipulations of perception and action are common and often comprise the control of events, such as opening or closing liquid crystal goggles. Most of these events are externally controlled, independent of the actions of the participants. Less common, although sometimes desirable, are event manipulations that are dependent on the unconstrained movements of participants. As an example, we describe a method we used previously to manipulate vision of basketball jump shooters on the basis of on-line registration of their own movements. The shooters wore liquid crystal goggles that opened or shut as a function of specific kinematic features of these movements. The novel aspect of this method is that the criteria for detecting movement patterns and performing the appropriate manipulations are adjustable to the specific sport context and the complexity and variations of the unconstrained movements. The method was implemented as a finite state machine: a computer system that can be used for pattern recognition. We discuss this method, how it works and the potential it has for studying perceptual-motor skills in sport. Furthermore, the results of the basketball experiment are briefly summarized and complemented with new analyses.     

Kinematics of cycling in relation to anterior knee pain and patellar tendinitis

The coronal and sagittal plane leg movements of 24 experienced male cyclists were assessed using video analysis while cycling on a Kingcycle windload simulator. The cyclists were grouped into those with a history of injury and an asymptomatic group on the basis of self-reported injury status. The ages, cycling experience, competition distances and competition speeds of the two groups were compared using Student's t-test. No significant differences (P < 0.05) were found for any of these variables. The maximum and minimum shank adduction, shank adduction velocities, knee flexion and ankle dorsiflexion values were also compared using Student's t-test. Significant differences were found at the point of maximum adduction (1.9 degrees; P = 0.019) and minimum dorsiflexion (4.9 degrees; P = 0.014). These differences indicated more dorsiflexion and greater abduction on the part of the symptomatic cyclists, supporting previous research that found that cyclists with a history of injury differ from those without a history of injury in the coronal plane leg movement patterns they adopt. Also, the most extreme medial position of the knee relative to the ankle occurred during knee extension. This supports the potential injury mechanism proposed by Francis (1986), which had previously only been examined using coronal plane kinematics.     

Mechanisms of attentional cueing during observational learning to facilitate motor skill acquisition

We examined the effectiveness of different cueing conditions during observational learning of a soccer accuracy pass. Sixty participants (30 males, 30 females) were randomly assigned and stratified by sex into one of six groups: discovery learning, verbal instruction, video model with visual cues, video model with verbal cues, video model with visual and verbal cues, and video model only. Each participant completed eight blocks of 10 trials each, with trial blocks 1 and 2 representing the practice phase (no manipulation), trial blocks 3, 4, 5 and 6 the acquisition phase (manipulation administered) and trial blocks 7 and 8 the retention phase (24 h after acquisition, with no manipulation). Absolute error, variable error and kicking form were recorded. The results indicated that those who used video modelling with visual and verbal cues collectively displayed less error and more appropriate form across acquisition and retention trial blocks compared with other groups. Our findings suggest that verbal information in addition to visual cues enhances perceptual representation and retention of modelled activities to improve task reproduction capabilities. Future research directions are proposed with implications for both direct and indirect perception accounts of skill acquisition through observed behaviours.     

Energy cost of different skating techniques in cross-country skiing

The aims of this study were to compare the aerobic energy cost of four 'on-snow' skating techniques in cross-country skiing and to examine the relationships between performance and aerobic energy cost. Twelve male skiers from recreational to national standard performed four level skating trials of 6 min duration in random order, each at the same submaximal velocity but with a different skating technique: (1) 'offset' (V1), using a double asymmetrical and asynchronous pole plant as weight is transferred to one ski; (2) 'two-skate' (V2A), where the pole plant is symmetrical; (3) 'one-skate' (V2), where there is a pole plant as weight is transferred to each ski; and (4) 'conventional', without poles. Oxygen uptake (VO2), pulmonary ventilation, the respiratory exchange ratio and heart rate were measured using a K4(b2) portable gas analyser. The aerobic energy cost (VO2/mean speed) and heart rate were higher (P < 0.05) in the one-skate than in the offset condition. This may be explained by the greater and more efficient use of the upper body and the lower variation in centre of gravity velocity in the offset condition. The aerobic energy cost was 5-9% higher (P < 0.01) in the conventional than in the other techniques, probably because of the shorter duration of propulsive forces within a cycle in the conventional skating condition. Moreover, in ski skating, the mechanical efficiency (propulsive forces/total forces) was shown to be higher in the upper than in the lower limbs. The correlation coefficient between performance and aerobic energy cost was significant in the two-skate (r = 0.68, P = 0.02), one-skate (r = 0.72, P = 0.01) and conventional (r = 0.62, P = 0.04) conditions, but not in the offset condition (r = 0.50, P = 0.10). Our results stress the importance of the upper body component in cross-country skiing and that the aerobic energy cost discriminates between skiers of different standards.     

Validation of a stages of exercise change questionnaire

The purpose of this study was to examine evidence for the validity of a stages of change measure of the Transtheoretical Model for exercise behavior. Participants were 152 university students (53.3% women, 71.6% Caucasian, M age = 19.18 years) who completed processes of change, self-efficacy, decisional balance, stages of change, and exercise behavior questionnaires as well as a maximal treadmill test. Participants in the action and maintenance stages had the highest strenuous (PC/C/P < A/M) and moderate (PC/C < A/M) self-reported exercise behavior. Those in the maintenance stage had the highest estimated aerobic fitness (PC/P < MA). The differences between the early stages (PC, C, and P) and the later stages (A and M) as described by the first function were primarily due to the behavioral process of change. The differences between the extreme stages (PC and M) and the middle stages (C, P, and A) were due to the experiential processes of change and the pros of decisional balance. The hypothesized patterns of stage differences were partially supported. Failure to obtain full support may have been due to methodological issues or inherent difficulties in detecting evidence for the validity of stages of change measures.     

User satisfaction survey and usage of an electronic desktop document delivery service at an academic medical library

In June 2000, the Biomedical Library at the University of South Alabama introduced Prospero, an electronic desktop document delivery service. From June 2000 to November 2002, Prospero delivered 28% of interlibrary loan requests and 72% of document delivery requests. In November 2002, the library conducted a user satisfaction survey of the Prospero service. Forty-two surveys were used. Fifteen responses were received from affiliated faculty, staff, and students, who generally expressed satisfaction with the service. Twenty-seven responses were received from unaffiliated users, comprised of medical libraries, individual users, and businesses. Based on the survey results, the library deemed the Prospero service a success. To better support users, the library's Web page was updated to include hardware and software requirements for successful use of the Prospero service, as well as screen shots of the Prospero process.     

Information--movement coupling: implications for the organization of research and practice during acquisition of self-paced extrinsic timing skills

Information--movement coupling is a fundamental concept, integral to theorizing on the coordination of goal-directed activity in ecological psychology. In this paper, we examine the implications of this concept for the design of experimental research and the organization of practice during the acquisition of movement coordination in sport tasks. The task vehicle for our analysis is interceptive actions, in particular self-paced extrinsic timing tasks exemplified by serving in sports such as volleyball. Recent research highlighting the relevance of information--movement coupling for the process of practice in sport is discussed. We conclude that information--movement coupling represents an important principle for the structural organization of research and practice in self-paced extrinsic timing tasks and that further work is required to verify its significance across a range of sport movements.     

新版《新华词典》体育词汇举凡

《新华词典》是一部重要的中型工具书,共收录体育词汇281条。着重对这些词汇的释义方式、类型进行简要分析和归纳,指出其中的问题所在。