Understanding the effect of finger–ball friction on the handling performance of rugby balls

Handling errors are often seen in professional rugby games and even more so in amateur rugby. This paper analyses the problem of ball mishandling using high-speed video footage of passes and a bespoke finger friction rig. The high-speed video analysis showed that when the ball is caught, often there is a fluctuating movement of the fingers over the surface of the ball. It also showed that the fingers move over the surface of the ball when the ball is thrown, confirming that the dynamic friction is a good measure of how easily a ball can be handled. Rugby ball surface samples were used, on a finger friction rig, to assess the coefficient of friction between the finger and the balls. The currently manufactured balls displaying the highest coefficients of friction in clean, dry conditions were the design with square, ‘sharp’ pimples and also the design with a mixture of small and large pimples. The most consistent ball across wet and dry conditions was the ball with round, large, densely populated pimples. It was also shown that when water is added to the surface of the ball or finger, there was little variation in performance between the ball varieties.     

The effect of normal load force and roughness on the dynamic traction developed at the shoe–surface interface in tennis

During tennis-specific movements, such as accelerating and side stepping, the dynamic traction provided by the shoe–surface combination plays an important role in the injury risk and performance of the player. Acrylic hard court tennis surfaces have been reported to have increased injury occurrence, partly caused by increased traction that developed at the shoe–surface interface. Often mechanical test methods used for the testing and categorisation of playing surfaces do not tend to simulate loads occurring during participation on the surface, and thus are unlikely to predict the human response to the surface. A traction testing device, discussed in this paper, has been used to mechanically measure the dynamic traction force between the shoe and the surface under a range of normal loading conditions that are relevant to real-life play. Acrylic hard court tennis surfaces generally have a rough surface topography, due to their sand and acrylic paint mixed top coating. Surface micro-roughness will influence the friction mechanisms present during viscoelastic contacts, as found in footwear–surface interactions. This paper aims to further understand the influence micro-roughness and normal force has on the dynamic traction that develops at the shoe–surface interface on acrylic hard court tennis surfaces. The micro-roughness and traction of a controlled set of acrylic hard court tennis surfaces have been measured. The relationships between micro-roughness, normal force, and traction force are discussed.     

The effect of chalk on the finger–hold friction coefficient in rock climbing

The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were performed. Participants hung from holds which were fixed on a specially designed hang board. The inclination of the hang board was progressively increased until the climber's hand slipped from the holds. The angle of the hang board was simultaneously recorded by using a gyroscopic sensor and the friction coefficient was calculated at the moment of slip. The results showed that there was a significant positive effect of chalk on the coefficient of friction (+18.7% on limestone and +21.6% on sandstone). Moreover sandstone had a higher coefficient of friction than limestone (+15.6% without chalk, +18.4% with chalk). These results confirmed climbers' belief that chalk enhances friction. However, no correlation with humidity/temperature and friction coefficient was noted which suggested that additional parameters should be considered in order to understand the effects of climate on finger friction in rock climbing.     

Acute effects of static stretching on characteristics of the isokinetic angle – torque relationship,surface electromyography,and mechanomyography

Abstract

The aims of this study were to examine the acute effects of static stretching on peak torque, work, the joint angle at peak torque, acceleration time, isokinetic range of motion, mechanomyographic amplitude, and electromyographic amplitude of the rectus femoris during maximal concentric isokinetic leg extensions at 1.04 and 5.23 rad · s^?1 in men and women. Ten women (mean ± s: age 23.0 ± 2.9 years, stature 1.61 ± 0.12 m, mass 63.3 ± 9.9 kg) and eight men (age 21.4 ± 3.0 years, stature 1.83 ± 0.11 m, mass 83.1 ± 15.2 kg) performed maximal voluntary concentric isokinetic leg extensions at 1.04 and 5.23 rad · s^?1. Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. Peak torque, acceleration time, and electromyographic amplitude decreased (P≤ 0.05) from pre- to post-stretching at 1.04 and 5.23 rad · s^?1; there were no changes (P > 0.05) in work, joint angle at peak torque, isokinetic range of motion, or mechanomyographic amplitude. These findings indicate no stretching-related changes in the area under the angle – torque curve (work), but a significant decrease in peak torque, which suggests that static stretching may cause a “flattening” of the angle – torque curve that reduces peak strength but allows for greater force production at other joint angles. These findings, in conjunction with the increased limb acceleration rates (decreased acceleration time) observed in the present study, provide tentative support for the hypothesis that static stretching alters the angle – torque relationship and/or sarcomere shortening velocity.     

Coach–athlete attachment and the quality of the coach–athlete relationship: implications for athlete’s well-being

Abstract

This study examined whether athletes’ attachment styles with the coach were linked to aspects of the coach–athlete relationship quality and, in turn, whether relationship quality was linked to athletes’ well-being. One hundred and ninety-two athletes completed a questionnaire measuring their attachment styles and relationship quality with the coach as well as their feelings of positive affect (PA) and negative affect (NA). Structural equation modelling (SEM) analysis found athletes’ avoidant and secure attachment styles to be associated with aspects of coach–athlete relationship quality such as social support, relationship depth, and interpersonal conflict. Interpersonal conflict appeared to play a key role in athletes’ PA and NA. From a practical perspective, an understanding of conflict management could provide a resource that allows athletes (and coaches) to enhance the quality of their sporting relationships. Specifically, an awareness of proactive strategies (e.g., steps to clarify expectations) and reactive strategies (e.g., cooperation during the discussion of disagreements) could potentially lead both coaches and athletes to “broaden” their viewpoints and in turn “build” connections that are capable of generating positive emotions including interest, excitement, happiness, and zeal.     

Do previous sports experiences influence the effect of an enrichment programme in basketball skills?

The aim of this study was to examine the effect of an enrichment programme in motor, technical and tactical basketball skills, when accounting for the age of youth sport specialisation. Seventy-six college students (age: M = 20.4, SD = 1.9) were allocated according to three different paths: (i) non-structured (n = 14), (ii) early specialisation (n = 34), and (iii) late specialisation (n = 28), according to information previously provided by the participants about the quantity and type of sporting activities performed throughout their sporting careers. Then, the participants of each path were randomly distributed across control and experimental groups. Variables under study included agility, technical skills circuit, as well as tactical actions performed in a 4-on-4 full-court basketball game. The results indicated improvements in the early and late specialisation paths namely in the experimental training groups. However, the late specialisation path revealed larger benefits, in contrast with the non-structured path, which showed less sensitivity to the enrichment programme, mostly sustained in physical literacy and differential learning. Higher improvements were observed in agility, and also in reducing the number of unsuccessful actions performed during the game. Overall, this study provided evidence of how early sports experiences affect basketball skill acquisition and contribute to adapt to new contexts with motor and technical-tactical challenges. In addition, a path supported by late specialisation might present several advantages in sport performance achievement.     

Child-rearing in public spaces: the challenging dual-role relationships of parent–coaches and child–athletes of coaches in Swedish team sports

ABSTRACT

The aim of this study was to examine the challenges of being either a parent–coach or a child–athlete of a coach within the context of Swedish youth sport. Conceptually, this paper draws on educational and sociological theories regarding changing perspectives in child-rearing. The results are based on data gathered from interviews with parent–coaches and child–athletes (age 13–15) of coaches involved in team sports. The results indicate that a range of meanings emerged through these unique sets of interactions, resulting in both positive and negative experiences for both children and their parents. To manage the perceived challenges, four behavioural strategies were used including fairness, distancing, defence and quitting. Overall, this study provides a deeper understanding of the challenges of these unique dual roles in relation to contemporary child-rearing perspectives.     

Effects of modelling and observer's ego involvement on warm‐up decrement

Warm‐up decrement (WUD), a phenomenon associated with motor behaviour, is the temporary decrement that occurs when performance resumes after a period of inactivity. The purpose of this study was to examine the extent to which observing a model while concerned about one's own subsequent performance (e.g. a substitute about to enter the sport contest) influences WUD. The subjects were randomly assigned to one of four conditions: (1) observing an ego‐involved model demonstrate the criterion skill, (2) observing a model while not ego‐involved, (3) ego involvement without modelling and (4) resting (control). Performance outcome (accuracy) and arousal (cognitive and somatic) were assessed. The results of the study indicated that only the combined ego involvement plus modelling condition eliminated WUD. Positive rather than negative emotions and heart rate increased significantly for these subjects after rest. In contrast, the other conditions each exhibited WUD. Heart rate was significantly higher in the ‘model and ego’ and ‘ego only’ groups as opposed to ‘modelling only’ and rest. Implications for using cognitive strategies while observing competitors just prior to entering the contest on reducing WUD are discussed.     

Different durations within the method of best practice affect the parameters of the speed–duration relationship

The aim of the study was to determine whether estimates of the speed–duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2–15?min. Ten triathletes (mean?±?SD age: 31.0?±?5.7?years; height: 1.81?±?0.05?m; body mass: 76.5?±?6.8?kg) performed two randomly assigned field tests to determine critical speed (CS) and the total distance covered above CS (D?). CS and D? were obtained using two different protocols comprising three TT that were interspersed by 60?min passive rest. The TTs were 12, 7, and 3?min in Protocol I and 10, 5, and 2?min in Protocol II. A linear relationship of speed vs. the inverse of time (s?=?D??×?1/t?+?CS) was used to determine parameter estimates. Significant differences were found for CS (p?=?0.026), but not for D? (p?=?0.123). The effect size for CS (d?=?0.305) was considered small, while that for D? was considered moderate (d?=?0.742). CS was significantly correlated between protocols (r?=?0.934; p?D? (r?=?0.053; p?=?0.884). The 95% limits of agreement were ±0.28m?s^?1 and ±73.9?m for CS and D?, respectively. These findings demonstrate that the choice of exhaustive times within commonly accepted durations results in different estimates of CS and D?, and thus protocols cannot be used interchangeably. The use of a consistent protocol is therefore recommended, when investigating or monitoring the speed–duration relationship estimates in well-trained athletes.     

A coaches’ perspective on the contribution of anthropometry,physical performance,and motor coordination in racquet sports

ABSTRACT

Differences and similarities between table tennis and other racquet sports exist, but are not well documented in the literature, in spite of the relevance for talent identification. In this study we aimed at identifying the key characteristics of table tennis in comparison with tennis and badminton based upon a survey in coaches. A total of 177 licensed coaches from all across the world and with diverse professional backgrounds completed a survey on anthropometric measures, physical performance, and motor coordination skills. On a scale from 1 to 10, coaches indicated to what extent a talent characteristic was important for their sport. MANOVA identified key differences as well as similarities between all three racquet sports and a subsequent discriminant analysis allocated coaches correctly for table tennis, tennis, and badminton 81.01%, 55.6%, and 71.4% respectively. Our results show that table tennis and other racquet sport coaches are well aware of differences between the racquet sports and also the importance and value of testing and assortment of skill components. These findings can assist coaches in future talent orientation and transfer in racquet sports.     

Teachers in school sports: between the fields of education and sport?

According to the cultural sociologist Pierre Bourdieu, gaining access to a social space or a position within a social space requires a specific capital. For teachers, this is normally indicated by a valid teaching certificate with relevant subject knowledge. However, when no qualified teachers are available, which is the case for the subject of school sports in Sweden, other assets gain recognition. Drawing on Bourdieu's conceptual framework, this paper examined the conditions for school sports in Sweden, and based on questionnaires answered by 109 teachers, explored the competencies, education and backgrounds teachers in upper secondary school sports possess. The paper address the question: what valuable resources are required to become a teacher of school sports and gain recognition as symbolic capital? The results show that while school sports in Sweden are carried out through a school subject and thus regulated by the government, it is influenced by both the fields of education and sport. Furthermore, the questionnaire results show that a majority of the teachers are employed as coaches instead of teachers and that less than half of them (45%) have a teacher education background, while 95% have a coaching education background. However, the results also show that teachers assessed their competencies for teaching school sports as high, especially with regard to competencies in specific sport skills. In conclusion, this paper shows how coaching education and experience in competitive sports are an important resource required to become a teacher in school sports and is thus recognized as symbolic capital. Therefore, school sports cannot be viewed as a legitimate part of the field of education but can be viewed as a part of the field of sport.     

Sport,politics and the labour movement: the British workers' sports federation, 1923–1935

Reading articles about the Tarahumara Indians of Northern Mexico that have appeared in popular US magazines, I identify four interlocking themes that constitute the Tarahumaras as a ‘white man's Indian’: a) the Tarahumaras are primitive hunters; b) they eat a simple and healthy diet; c) they complete superhuman feats of endurance; and d) they lack the sense of time/work discipline that would make them successful athletes in Western-style endurance events. These themes constitute the Tarahumaras as noble savages whose supposedly primitive lifestyle offers US runners a solution for the diseases of overcivilization. They also serve the needs of a burgeoning sport/tourism industry that sells stereotypical images of ‘Indians’ to US runners and tourists.     

The fourth dimension: A motoric perspective on the anxiety–performance relationship

This article focuses on raising concern that anxiety–performance relationship theory has insufficiently catered for motoric issues during, primarily, closed and self-paced skill execution (e.g., long jump and javelin throw). Following a review of current theory, we address the under-consideration of motoric issues by extending the three-dimensional model put forward by Cheng, Hardy, and Markland (2009) (‘Toward a three-dimensional conceptualization of performance anxiety: Rationale and initial measurement development, Psychology of Sport and Exercise, 10, 271–278). This fourth dimension, termed skill establishment, comprises the level and consistency of movement automaticity together with a performer's confidence in this specific process, as providing a degree of robustness against negative anxiety effects. To exemplify this motoric influence, we then offer insight regarding current theories’ misrepresentation that a self-focus of attention toward an already well-learned skill always leads to a negative performance effect. In doing so, we draw upon applied literature to distinguish between positive and negative self-foci and suggest that on what and how a performer directs their attention is crucial to the interaction with skill establishment and, therefore, performance. Finally, implications for skill acquisition research are provided. Accordingly, we suggest a positive potential flow from applied/translational to fundamental/theory-generating research in sport which can serve to freshen and usefully redirect investigation into this long-considered but still insufficiently understood concept.     

The effect of video‐feedback on the learning of the tennis service by intermediate players

Effects of video‐feedback on improvement of the tennis service were investigated in subjects having at least 2 years of playing experience in tennis. The experiment was carried out in an indoor tennis hall under normal training conditions.

Subjects were randomly divided into three groups: a video‐feedback training (VFT) group, a traditional training (TT) group and a control group, each consisting of 22 subjects. While the subjects of the control group received no training at all, subjects in both the VFT and TT groups were trained twice weekly during 5 consecutive weeks. Each training session lasted 40 min, of which 30 min was spent on actual practice in training of the service. The remaining 10 min was spent on watching, analysing and discussing video recordings of either their own service performed during the training session (VFT group), or ground strokes and volleys of top level players (TT group). Both the VFT and TT group showed significantly greater improvements in both achievement scores and form (technique) scores than did the control group. No differences, however, could be demonstrated between the VFT and TT group, indicating that the subjects of the former group did not benefit from the video‐feedback they received.

While form scores correlated significantly (P < 0.001) with the velocity of the served ball, no such relation between form scores and spatial accuracy was apparent.