Influence of Instruction on Velocity and Accuracy in Soccer Kicking of Experienced Soccer Players

ABSTRACT. The authors’ aim was to investigate the speed-accuracy tradeoff in soccer kicking with the dominant and nondominant foot by using different types of instructions prioritizing speed or accuracy in experienced soccer players. Ten male soccer players were randomly given 1 of the 4 instructions that differed in aspects of the kick they should emphasize and what the secondary aim would be (speed or accuracy). It was found that ball velocity was affected by instruction in the expected way: emphasis on accuracy and ball velocity reduced for both kicking feet. In addition kicking accuracy increased when emphasizing this, but only with the dominant foot indicating that Fitts’ law only was found in kicks with the dominant foot.     

A comparison between novices and experts of the velocity-accuracy trade-off in overarm throwing

Expert team-handball players do not show the typical trade-off between speed and accuracy in overarm throwing. Van den Tillaar and Ettema (2003a) attributed this result to the uniqueness of the training experience of this group. The purpose of this study was to test their hypothesis by comparing experts with novices on overarm throwing by manipulating the goal of the task using different instructions. No trade-off between speed and accuracy was found for novices (n = 13; M age = 22.7 yr., SD = 2.2) or experts (n = 9; Mage = 24 yr., SD = 2.2): accuracy did not change by instruction. Furthermore, the linear velocities of the ball and endpoints of body segments and their timing were affected by instruction in a similar fashion in both groups. This finding indicates that training experience is not related to speed-accuracy tradeoff in overarm throwing.     

Movement variability and skill level of various throwing techniques

In team-handball, skilled athletes are able to adapt to different game situations that may lead to differences in movement variability. Whether movement variability affects the performance of a team-handball throw and is affected by different skill levels or throwing techniques has not yet been demonstrated. Consequently, the aims of the study were to determine differences in performance and movement variability for several throwing techniques in different phases of the throwing movement, and of different skill levels. Twenty-four team-handball players of different skill levels (n=8) performed 30 throws using various throwing techniques. Upper body kinematics was measured via an 8 camera Vicon motion capture system and movement variability was calculated. Results indicated an increase in movement variability in the distal joint movements during the acceleration phase. In addition, there was a decrease in movement variability in highly skilled and skilled players in the standing throw with run-up, which indicated an increase in the ball release speed, which was highest when using this throwing technique. We assert that team-handball players had the ability to compensate an increase in movement variability in the acceleration phase to throw accurately, and skilled players were able to control the movement, although movement variability decreased in the standing throw with run-up.     

Interaction between preference and instructions for a focus of attention in billiards

The present study evaluated the interaction between preference for a focus of attention and instructions for focusing attention. 4 experienced billiard players had to shoot a billiard ball into a target area and received a focus instruction either corresponding or opposite to their preferred focus of attention. Two-dimensional error scores of accuracy and consistency were obtained. Accuracy of performance increased between Phase 1 without instructions and Phase 2 with focus instructions, independent of preference or instruction. However, participants with a preference for an external focus receiving an internal focus instruction showed less consistent performance.     

Quiet eye training improves throw and catch performance in children

ObjectivesTo compare quiet eye training (QET) and ‘traditional’ technical training (TT) interventions for a throw and catch task in children.DesignThis pilot study adopted a between groups randomized control design.MethodSixteen, 10 year-old typically developing children performed 10 pre- and 10 post-test trials before and after QET or TT, while wearing a Mobile Eye gaze registration system. Both interventions consisted of three video demonstrations (focusing on the throw, the catch, and linking the throw and catch) followed by a series of practice trials. QET videos emphasized gaze strategy instructions whereas TT videos emphasized traditional primary school throwing and catching instructions.ResultsSignificant interaction effects for performance and quiet eye durations revealed that only the QET group significantly lengthened QE durations, which contributed to significant improvements in catching from pre- to post-test.ConclusionsQET may be an effective method for improving throwing and catching skills in typically developing children.     

Team Sports Players' Observed Aggresion as a Function of Gender, Competitive Level, and Sport Type

This study aims at examining observed aggression in team sports as a function of gender, competitive level, and sport type. It was hypothesized that (a) male players display more aggressive behaviors than female players, (b) aggressive behaviors increase when competitive level rises, and (c) gender difference in observed aggression is depending on sport type. One hundred and eighty games, equally shared among males and females, soccer and handball, and departmental, regional, and national competitive levels were recorded on videotapes and observed using a grid to differ instrumental from hostile aggressive behaviors. The results revealed that male players always display more aggressive behaviors than female players, whatever the sport, the competitive level or the nature of the observed aggression; instrumental aggressive behaviors increase and hostile aggressive behaviors decrease when competitive level rises; and the gender difference appears larger in handball than in soccer.     

The effect of attentional instructions during modeling on gaze behavior and throwing accuracy in 7 to 10 year-old children

Research has shown the effectiveness of attentional instructions and observation on the performance and learning in children. However, there is little research on the effects of instruction that manipulates attentional focus during observation. The purpose of the study was to investigate performance following instructions that directed an individual to focus internally or externally during the viewing of a model. Eye tracking was also used to investigate the visual search strategy under different instructional groups. 24 children between the ages of 7 and 10 years were randomly divided into an internal (IFM) or external (EFM) modeling group. Children performed a 10-trial pre-test to measure throwing accuracy and quiet eye duration (QED). Following pre-test, children observed a model performing the correct overarm throw 10 times while eye movement was recorded. They then performed a 10-trial post-test. Results revealed that both groups improved accuracy from pre-test to post-test (p < .001) and increased QED from pre- to post-test (p < .001). It was also observed that EFM had greater accuracy and (p = .01) and longer QED (p < .001) than IFM during post-testing. Evidence was also observed for adherence to the attentional focus strategy as EFM and IFM looked more frequently at the specific cue provided (p < .001). Directing visual attention to the movement effects while observing a model significantly benefits motor performance and learning in children. Changing the focus of instruction to an external focus improved both throwing accuracy and increased QED.     

Decision-making in basketball and handball games: A developmental perspective

The study examined the way in which novice basketball or handball players used different informational cues (current score, time left to play, numerical status of the team) for deciding a quick restart of play during a basketball or a handball game. The study also compared their responses with the responses from a senior experts group. The more experienced the novices, (a) the more they gave importance to the numerical status and the current score for judging the appropriateness of the strategy, and (b) the more the effect of time moderated the effect of current score on the appropriateness judgments. These developmental trends were shown to be faster in basketball than in handball. Learning the conditions under which a quick restart of play is appropriate or not appeared as more difficult in the case of handball than in the case of basketball.     

Information underpinning anticipation of goal-directed throwing

We identified the information used to anticipate throw direction in handball. In two experiments, we examined how anticipation performance is affected when the information from one of five body areas (right arm, shoulders, hips, trunk, or total throw side) was either neutralized or decoupled from the motion of other body segments. In the first experiment, performance was significantly reduced when information from the throwing arm was neutralized, irrespective of skill levels. Skilled participants were negatively affected when the shoulders, hips, and trunk were neutralized, whereas less-skilled participants showed trends toward improvement under identical conditions. In the second experiment, partially disrupting relative motion via decoupling was not enough to reduce the anticipation performance among skilled participants to chance levels, whereas less-skilled participants lost their ability to anticipate in three conditions. Our findings suggest that skilled and less-skilled participants employ different information extraction strategies, yet information from the throwing arm is critical to anticipation for both groups. The two experiments suggest that relative motion mediated by both the absolute displacement trajectories of individual marker locations and their relative timings are important in informing anticipation, irrespective of skill level.     

Role Satisfaction Mediates the Relation between Role Ambiguity and Social Loafing among Elite Women Handball Players

The aims of the study were to develop a questionnaire on self-reported social loafing (SRSLQ), and then to examine its relations with role ambiguity and role satisfaction in a sample of 110 women handball players competing at the elite level in Norway. Structural equation modeling analyses indicated that the SRSLQ was a psychometrically sound measure. In line with the expectations, role satisfaction fully mediated the positive relation between role ambiguity and self-reported social loafing: The more players experienced role ambiguity, the less satisfied they were with their role in the team, and the more social loafing they reported.     

Measuring home advantage in Spanish handball

Since Pollard established the system for analysing home advantage in 1986, it has been demonstrated and quantified in various sports, including many team sports. This study aims to assess whether home advantage exists in handball, using a sample of more than 19,000 Spanish handball league games. Results of the games played at home and away, the sex of the players, and the levels of the competition were included as variables. In Spanish handball, there was a home advantage of 61%, which means, on average, the team playing at home wins 61% of points available. This value varies according to sex and according to competition level, increasing as competition level decreases and season rank improves.     

The informational properties of the throwing arm for anticipation of goal-directed action

We examined the informational value of biological motion from the arm in predicting the location of a thrown ball. In three experiments, participants were classified as being skilled and less skilled based on their actual performance on the task (i.e., using a within-task criterion). We then presented participants with a range of stick figure representations and required them to predict throw direction. In Experiment 1, we presented stick figure movies of a full body throwing action, right throwing arm plus left shoulder and throwing arm only. Participants were able to anticipate throw direction above chance under all conditions irrespective of perceptual skill level, with the perceptually skilled participants excelling under full body conditions. In Experiment 2, we neutralized dynamical differences in motion to opposing throw directions from the shoulder, elbow and wrist of the throwing arm. Neutralizing the wrist location negatively affected anticipation performance in all participants reducing accuracy to below chance. In Experiment 3, we presented movies of the motion wrist location alone and the upper section of the throwing arm (shoulder-elbow). Participants were able to successfully anticipate above chance in these latter two conditions. Our findings suggest that motion of the throwing arm contains multiple sources of information that can help facilitate the anticipation of goal-directed action. Perceptually skilled participants were superior in extracting informational value from motion at both the local and global levels when compared to less skilled counterparts.     

Retention of Quiet Eye in Older Skilled Basketball Players

There is mounting research to suggest that cognitive and motor expertise is more resistant to age-related decline than more general capacities. The authors investigated the retention of skills in medium-aged skilled (n = 14) and older-aged skilled (n = 7) athletes by comparing them with medium-aged less skilled (n = 15) and older-aged less skilled (n = 15) participants. Participants performed basketball free throws and dart throws as a transfer task under standardized conditions. Motor performance (accuracy) and perceptual performance (quiet eye) were examined across the four groups. There were significant differences between skill groups and age groups in throwing accuracy on both throwing tasks. Skilled players outperformed less skilled and medium-aged players outperformed older-aged players in basketball and dart throws. There were no significant differences in quiet eye duration across the skill or age groups in either task. These results indicate expertise in a perceptual motor task such as the basketball free throw can be retained in older athletes and that present models of skill maintenance should be re-evaluated to consider the issue of transfer.     

Motor control in dart throwing

This study investigates the underlying mechanism for controlling a dart throw. A single subject threw darts at a standard dartboard in two distance conditions; from 8.5 ft and 7.5 ft. The throwing action of the subject was monitored using the Selspot movement monitoring system. 10 hits (bullseyes), 10 high misses (throws which land in the vertical plane above the bullseye) and 10 low misses (throws which land in the vertical plane below the bullseye) were recorded. Predictions from open-loop, closed-loop and schema models of motor control, regarding the possible patterns of positional variance over time during the throw, are explored. There is an attempt to discover what aspects of the throw determine whether it will hit the target or not and what parameters of the throw are changed to accommodate a different throwing distance. The results are not inconsistent with an open-loop explanation for control of the throw. Given that whether a throw is a hit or not seems to depend on factors probably out of the subjects control, the success of any one throw may be a matter of chance. Rather than parameters of the original throw being re-calibrated to accommodate a new throwing distance a completely new throw is selected.     

Predicting persistence or withdrawal in female handballers with social exchange theory

Two complementary studies were conducted to explain the dropout phenomenon with French female handball players, utilizing the tenets of social exchange theory (Thibaut & Kelley, 1959; Rusbult, 1980). In the first study, the aim was to more fully explore the sources of enjoyment by emphasizing the key variables in the costs/benefits analysis. We postulate that the costs/benefits analysis consists in each athlete estimating the probability of reaching the most desired consequences for him or her (e.g., learn and improve skill, affiliation with others, be better than the others). The subjects were 488 French women aged from 15–19 years. Structural equation modeling (SEM) revealed that enjoyment in handball was predicted by a latent variable (named perceived benefits) subjacent to perceptions of competence, autonomy, relatedness, progress, coach's support, and time of play. In the second study, we tested a sport commitment model based on the social exchange postulates, using SEM analyses and a prospective design over 8 months. In view of the results of study 1, we replaced the construct of enjoyment with perceived benefit. This analysis provides a more comprehensive understanding of the enjoyment construct and is more consistent with the notion of cost and benefits outlined in social exchange theory. Participants were 253 French handball players between the ages of 14 and 16 years. A first set of analyses, focused on the differences, showed that dropout players perceived themselves as significantly less competent, less autonomous, less related to their team, lower in progress and less supported by their coach than persistent players. The second set of analyses with SEM revealed that the commitment level was positively associated with perceived benefits and negatively with social constraints and alternatives opportunities. Finally, a lack of commitment led to dropping out of the sport 8‐months later.     

Effect of stride length on overarm throwing delivery: A linear momentum response

Changing stride length during overhand throwing delivery is thought to alter total body and throwing arm linear momentums, thereby altering the proportion of throwing arm momentum relative to the total body. Using a randomized cross-over design, nineteen pitchers (15 collegiate and 4 high school) were assigned to pitch two simulated 80-pitch games at ±25% of their desired stride length. An 8-camera motion capture system (240 Hz) integrated with two force plates (960 Hz) and radar gun tracked each throw. Segmental linear momentums in each plane of motion were summed yielding throwing arm and total body momentums, from which compensation ratio’s (relative contribution between the two) were derived. Pairwise comparisons at hallmark events and phases identified significantly different linear momentum profiles, in particular, anteriorly directed total body, throwing arm, and momentum compensation ratios (P ⩽ .05) as a result of manipulating stride length. Pitchers with shorter strides generated lower forward (anterior) momentum before stride foot contact, whereas greater upward and lateral momentum (toward third base) were evident during the acceleration phase. The evidence suggests insufficient total body momentum in the intended throwing direction may potentially influence performance (velocity and accuracy) and perhaps precipitate throwing arm injuries.     

SPATIAL COGNITION AND GENDER Instructional and Stimulus Influences on Mental Image Rotation Performance

Recent research has demonstrated that "sex differences" on mental image rotation (MIR) tasks may be attenuated through manipulations of instructional or stimulus conditions. The interaction of these variables was examined in two experiments. In the first, subjects received instructions that emphasized or de-emphasized the spatial nature of the MIR task. In the second, instructions emphasized the use of MIR abilities in stereotypically "masculine" or "feminine" occupations. The relevant interactions were significant in both experiments. Men performed at higher levels than women in the spatial instruction conditions, but no sex differences were observed under nonspatial instructions. These effects were further shown to be mediated by stimulus type; simpler or more familiar stimuli were less deleterious to the performance of women. These results add to the evidence that instructional and stimulus effects may exacerbate or eliminate sex differences in spatial cognition.     

Observation and analysis of large-scale human motion

Many team sports include complex human movement, which can be observed at different levels of detail. Some aspects of the athlete's motion can be studied in detail using commercially available high-speed, high-accuracy biomechanical measurement systems. However, due to their limitations, these devices are not appropriate for studying large-scale motion during a game (for example, the motion of a player running across the entire playing field). We describe an alternative approach to studying such large-scale motion, and present a video-based, computer-aided system, developed specifically for the purpose of acquiring large-scale motion data. The baseline of our approach consists of sacrificing much of the spatial accuracy and temporal resolution of widely used biomechanical measurement systems, to obtain data on human movement that span large areas and long intervals of time. Data can be obtained for each of the observed athletes with reasonable amount of operator work. The system was developed using the recordings of a handball match. Several field tests were performed to assess measurement error, including comparison to one of the widely available biomechanical measurement systems. With the help of the system presented, we could obtain position data for all 14 handball players on a 40 x 20 m large court with RMS error better than 0.6 m, covering 1 h of action. Several results, obtained during the handball match study are presented, in order to highlight the importance of large-scale motion acquisition.     

Transformational leadership and team performance in sports teams: A conditional indirect model

This study tests how transformational leadership fosters team performance through team cohesion and how that relationship is moderated by previous team performance and leadership consensus. We computed a moderated-mediation model based on a sample of 690 professional players in 59 top professional teams in interactive team sports leagues (basketball, handball, roller hockey, and indoor football/soccer) in Spain. Our findings suggest that transformational leadership indirectly influences objective team performance through the mediation role of team cohesion and that this indirect effect is more prominent when the level of previous performance is higher. We also found that the indirect effect of transformational leadership on team performance via cohesion is stronger in teams with higher consensus regarding their coaches' leadership. Overall, our results demonstrate the importance of integrating dispersion and contextual variables into research models, in particular, previous performance and leadership consensus.