The importance of the International Tennis Federation's junior boys' circuit in the development of professional tennis players

Abstract

The relationship between junior boys' tennis success, as measured by a top 20 International Tennis Federation's Junior Circuit (ITFJC) ranking, and subsequent ranking accomplishments in professional men's tennis is discussed. The names, countries, and birthdates of all players to achieve a top 20 ITFJC boys' year-end ranking from 1992 to 1998 were recorded. The progress of these players through the professional ranks was then tracked to the end of 2004. Results indicate that 91% of top 20-ranked boys achieved a professional men's ranking, while a stepwise regression analysis revealed junior ranking (JR) to be a predictor of future, professional ranking (β = 0.232, r ² = 0.054, p < 0.05). A regression equation [predicted professional rank = 78.17 + 6.31?(JR)] accounted for a significant amount of variance in professional ranking. For male players, therefore, the achievement of a top 20 junior ranking appears to be a reasonable yardstick for future, professional success. The type of surface upon which junior players develop their games was also shown to influence professional ranking highs, with play on clay courts or a combination of clay and hard courts helping to produce higher, professionally ranked players than hard court play alone (p≤ 0.01).     

Cycling power output produced during flat and mountain stages in the Giro d'Italia: A case study

Abstract

Until recently, the physiological demands of cycling competitions were mostly reflected by the measurement of heart rate and the indirect estimation of exercise intensity. The purpose of this case study was to illustrate the varying power output of a professional cyclist during flat and mountain stages of a Grand Tour (Giro d'Italia). Nine stage recordings of a cyclist of the 2005 Giro d'Italia were monitored using a mobile power measurement device (SRM Trainingssystem, Julich, Germany), which recorded direct power output and heart rate. Stages were categorized into flat (n = 5) and mountain stages (n = 4). Data were processed electronically, and the overall mean power in flat and mountain stages and maximal mean power for various durations were calculated. Mean power output was 132 W ± 26 (2.0 W · kg^?1 ± 0.4) for the flat and 235 W ± 10 (3.5 W · kg^?1 ± 0.1) for the mountain stages. Mountain stages showed higher maximal mean power (367 W) for longer durations (1800 s) than flat stages (239 W). Flat stages are characterized by a large variability of power output with short bursts of high power and long periods with reduced intensity of exercise, whereas mountain stages mostly require submaximal, constant power output over longer periods.     

Ball launch conditions for skilled golfers using drivers of different lengths in an indoor testing facility

Abstract

The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors.     

Responses to Forces Influencing Cohesion As a Function of Player Status and Level of Male Varsity Basketball Competition

Abstract

This exploratory study determined if the responses of male varsity basketball players to six factors influencing cohesion were a function of level of competitive intensity and/or the importance of the players to their team. Players on intact teams from five levels of competition – elementary school, junior high school, senior high school, small college and large college–responded to a cohesion questionnaire at the end of the season. Coaches designated five players with the most game playing time as “starters” and five players with the least game playing time as “reserves.” A team factor score for Team Performance Satisfaction, Self Performance Satisfaction, Task Cohesion, Affiliation Cohesion, Desire for Recognition and Value of Membership was calculated. Each team factor score served as the dependent variable in a 2 (player status) × 5 (level of competition) analysis ofcovariance design, with teams nested in the second factor. The won-loss record served as the covariate. Results indicated that “starters” were more satisfied with their own performance, were more task conscious, had a greater affiliation desire, and valued their membership on the team to a greater degree than the “reserves.” The elementary and junior high school team members were significantly more satisfied with the team's performance, were more satisfied with their own self performance, were more affiliation conscious, and valued their team membership to a greater degree than did college team members. The interaction between player status and level of competition was not significant for any of the factor scores.     

Competition and Instructional Set Effects On the Speed and Accuracy of a Throwing Task

Abstract

Two experiments were conducted to investigate the effects of competition and instructional sets on the speed and accuracy of a dart-throwing task. In both experiments individuals competed against another subject on one day, and performed under noncompetitive conditions on a second day. The five distinct instructional sets varied from extreme emphasis on speed to extreme emphasis on accuracy. Multivariate analyses of variance revealed main effects for instructional sets on speed and accuracy in both experiments. Strong tradeoffs occurred with speed slowing and accuracy improving as the instructional emphasis changed from speed to accuracy. A competition by instructional sets interaction in Experiment 2 indicated that competition facilitated speed when speed was important, but when instructions emphasized accuracy, speed was slower in competition than in noncompetition. Accuracy was not affected by competition.     

Making a career in PESP in the corporatized university: reflections on hegemony,resistance, collegiality and scholarship

This lecture considers how it might be possible to make a career as a university scholar at a time when the university is becoming increasingly corporatised. Consistent with the intent of the Physical Education and Sport Pedagogy (PESP) Special Interest Group (SIG) Scholar Lecture, I draw on personal experiences from my own career as a university teacher, researcher, teacher educator and leader to consider the extent to which the hegemony of corporatisation might be challenged and subverted, the kinds of resistance that can and should take place, and the central importance of collegiality and scholarship to the sustainability of the university as an institution of higher learning. I will consider more specifically what it means to develop a career as a scholar in a practical and marginalised field such as PESP, and the possibilities that exist to secure the future of the field of research and praxis.     

System approach to games and competitive playing

Abstract

The force enhancement of muscle twitch contraction after a maximal voluntary contraction (MVC) has been defined as post-activation potentiation. However, the effects of post-activation potentiation on ballistic movements have not been studied extensively, or the underlying neurophysiologycal mechanism. In the current study, we examined post-activation potentiation and spinal H-reflex excitability in the soleus muscle. Mechanical power during explosive ballistic plantar flexions was measured in 14 males before and after 5 s, 4 min, and 10 min of isometric conditioning (EPF_pre, EPF_5s, EPF_4min, EPF_10min, respectively). Four sessions corresponding to four different protocols of isometric conditioning were conducted. The protocols were different in the intensity (10% vs. 100% of MVC) and duration (7 vs. 10 s) of the isometric conditioning. The results showed a significant enhancement in mechanical power in EPF_4min compared with EPF_pre, only when the isometric conditioning was performed at 100% of MVC for 10 s. No significant changes were observed in the H-related parameters (e.g amplitude, threshold, H/M ratio) after the isometric conditioning. Our results show that to obtain a post-activation potentiation during explosive ballistic movements, the intensity and duration of the isometric conditioning must be controlled. Moreover, the improvement in mechanical power is not related to spinal H-reflex excitability.     

Pacing pattern and performance during the 2008 Olympic rowing regatta

Abstract

Data from the 2008 Olympic rowing regatta were analysed to determine the time distribution during races and to assess whether pacing patterns differ between heats and the corresponding finals. Absolute and relative sector times for all of the four 500 m race quarters were analysed, for all boats in all heavyweight heats and final races (n=72 boats for men, n=60 boats for women). Irrespective of race type, boat rank or boat type, analyses of variance with repeated measures revealed that absolute times in the second and/or third race quarter(s) were significantly (both sexes: P<0.001) longer than those either in the first or final quarter, resulting in a parabolic-shaped profile. Compared with the heats, the pacing pattern adopted during the finals was significantly different (females: P<0.013; males: P<0.001); that is, relatively slower in the first and second race quarter but relatively faster in the last quarter. The parabolic-shaped race profile indicates an anticipatory control of speed and energy distribution over the course of the 2000-m race. The observed changes in pacing pattern suggest that during the finals a more conservative starting pace is used, which could be physiologically advantageous, because some energy is withheld for the final spurt.     

Differences in ball speed and accuracy of tennis groundstrokes between elite and high-performance players

Abstract

The main aim of this study was to identify and compare ball speed and hitting accuracy of forehand and backhand groundstrokes between ATP professionals (elite) and high-performance youth players when shots were played cross-court and down the line to a target square. Six elite and seven high-performance tennis players volunteered to participate in the study. A Doppler-radar device and a digital video camera, operating at 120 frames per second, were used to measure ball speed and accuracy of forehand and backhand groundstrokes in the respective situation (cross-court and down the line). The results of 1040 measured groundstrokes indicate that the ball speed of the forehand and the backhand ground stroke was higher in the elite group when analysing (1) all valid shots, (2) the six fastest shots, and (3) the six most accurate shots (all P < 0.05). In addition, all players achieved a higher forehand speed compared with their backhand when balls were directed cross-court (P < 0.01). The participants demonstrated similar ability when considering accuracy of their groundstrokes (P > 0.05). However, a group difference for accuracy was identified when considering the six fastest forehand shots (P<0.05), and the forehand cross-court stroke was played more accurately than the backhand cross-court stroke by both groups (valid shots and six most accurate shots, P<0.05). Moreover, there was no evidence that players who impacted the ball faster were any less accurate than those who impacted the ball more slowly. Analyses for participants actually revealed a negative correlation between ball speed and mean radial error (accuracy) for the backhand down the line (r= ? 0.77, P<0.01). According to the results of this study, ball speed seems to be the determining factor that separates elite from sub-elite tennis players.     

Elite athletes' attitudes towards the use of placebo-induced performance enhancement in sports

Abstract

While an increasing number of research is devoted to the understanding of placebo effects in sports, athletes' experiences with and attitudes towards the use of placebo for performance enhancement remain poorly understood. In this study, 79 elite athletes from different sports were surveyed on five issues related to placebo use in sports. Results showed that 47% of the athletes have experienced placebo effects in the past. A majority of the athletes (82%) thought that placebos could affect their sports performances. A wider use of placebos in sport settings was endorsed more by those who have experienced placebo effects in the past than those who did not (P = .005). Regardless of past experience with placebo, more than half of the athletes (53%) would accept an unknown but legitimate substance from the coach, and 67% of them would not mind a placebo-linked deception if that was effective. These findings confirm that most elite athletes believe in the power of placebos in enhancing sports performance, and those having a positive past experience exhibit slightly more favourable attitudes in contrast to those without such experiences.