Coordination Patterns in Ball Bouncing as a Function of Skill

By observing the coordination patterns of people of different ages and skill levels bouncing a ball, the authors addressed hypotheses regarding (a) the relative increase and decrease of degrees of freedom with learning and (b) the order of progression in the changing organization of those degrees of freedom with development and learning. The movement patterns of the dominant arm and hand of subjects at various skill levels were contrasted in a cross-sectional design so that the way movement organization changes as a function of practice could be examined. Nine subjects aged between 4 and 22 years bounced a basketball at a preferred rhythm while standing still. Each performance trial was videotaped, and motions of arm and ball were digitized. Statistical analyses were made of linear and angular body motions: pairwise correlations and multiple regressions, amplitude and period variability, phase relations, and spectral and coherency measures. The coordination patterns revealed that (a) the movement patterns of less skilled subjects were more variable than those of more skilled subjects and (b) the motions of the articulators showed directional changes as a function of skill level that began both proximally and distally and moved toward the center of the effector chain with practice. The findings point up the relevance of studying change of system organization for understanding control and coordination.     

Basketball players minimize the effect of motor noise by using near-minimum release speed in free-throw shooting

The aim of this study was to clarify the strategy used by basketball players during free-throw shooting to improve performance in the presence of motor noise. Two possible hypotheses were examined: the players minimize the release speed to decrease signal-dependent noise or the players maximize the shot success probability by accounting for their variability. Eight collegiate players and one professional player participated in this study by attempting shots from the free-throw line using a motion capture system. The solution manifold consisting of ball parameters at release was calculated and the optimal strategy was simulated by considering ball parameter variability; this result was compared with the actual data. Our results showed that participants selected the solution of near-minimum release speed. The deviation of the measured release angle from the minimum-speed angle was close to zero (2.8 ± 3.1^∘). However, an increase in speed-dependent noise did not have a significant influence on the ball landing position through simulation. Additionally, the effect of release angle error on the ball landing position was minimum when using the minimum speed strategy. Therefore, the players minimize the release speed to minimize the effect of the release error on performance, instead of minimizing the speed-dependent noise itself. In other words, the strategy is “near-minimum-speed strategy” as well as “minimum-error-propagation strategy”. These findings will be important for understanding how sports experts deal with intrinsic noise to improve performance.     

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.     

Older adults exhibit altered motor coordination during an upper limb object transport task requiring a lateral change in support

Investigating an ecologically relevant upper limb task, such as manually transporting an object with a concurrent lateral change in support (sidestepping alongside a kitchen counter), may provide greater insight into potential deficits in postural stability, variability and motor coordination in older adults. Nine healthy young and eleven older, community dwelling adults executed an upper limb object transport task requiring a lateral change in support in two directions at two self-selected speeds, self-paced and fast-paced. Dynamic postural stability and movement variability was quantified via whole-body center of mass motion. The onset of lead lower limb movement in relation to object movement onset was quantified as a measure of motor coordination. Older adults demonstrated similar levels of stability and variability as their younger counterparts, but at slower peak movement velocity and increased task duration. Furthermore, older adults demonstrated asymmetrical motor coordination between left and right task directions, while younger adults remained consistent regardless of task direction. Thus, older adults significantly modulated movement speed and motor coordination to maintain similar levels of stability and variability compared to their younger counterparts.     

Postural sway and joint kinematics during quiet standing are affected by lumbar extensor fatigue

The purpose of this study was to investigate changes in postural sway and strategy elicited by lumbar extensor muscle fatigue. Specifically, changes in center of mass (COM), center of pressure (COP), and joint kinematics during quiet standing were determined, as well as selected cross correlations between these variables that are indicative of movement strategy. Twelve healthy male participants stood quietly both before and after exercises that fatigued the lumbar extensors. Whole-body movement and ground reaction force data were recorded and used to calculate mean body posture and variability of COM, COP, and joint kinematics during quiet standing. Three main findings emerged. First, participants adopted a slight forward lean post-fatigue as evidenced by an anterior shift of the COM and COP. Second, post-fatigue increases in joint angle variability were observed at multiple joints including joints distal to the fatigued musculature. Despite these increases, anterior-posterior (AP) ankle angle correlated well with AP COM position, suggesting the body still behaved similar to an inverted pendulum. Third, global measures of sway based on COM and COP were not necessarily indicative of changes in individual joint kinematics. Thus, in trying to advance our understanding of how localized fatigue affects movement patterns and the postural control system, it appears that joint kinematics and/or multivariate measures of postural sway are necessary.     

Disruption of kinematic coordination in throwing under stress

The present study tested the conscious-control theory of the relationship between stress and performance. Performers under stress conditions consciously attempted to control their movements, disrupting the automaticity of control. Twenty-two male subjects (11 in Experiment 1 and 11 in Experiment 2) performed an underhand ball-throwing task using the non-dominant hand. The inter-trial variability of two kinematic measures was analyzed, namely arm-joint coordination during the throw and hand position at release (release point). Experiment 1 confirmed the validity of regarding these variability measures as indices of automaticity, as they did not vary in spite of resource shortage induced by a dual-task paradigm. In Experiment 2, in which stress led to a detriment in performance, the variability of joint coordination increased, whereas the release point became more fixed. These findings imply that throwing performance is impaired when the coordination is disrupted as a result of inflexible movement executed by conscious control.     

Representative design: Does the addition of a defender change the execution of a basketball shot?

ObjectiveThe aim of this study was to examine the influence of a defender on the performance of a motor skill from an invasion sport.DesignHighly skilled basketball players performed different variations of basketball shots using a randomised test schedule.MethodParticipants completed a total of 30 test trials comprising 6 trials of 5 different shot types in both defended and undefended conditions.ResultsThe presence of a defender led to significant changes in several behavioral measures including faster shot execution times, longer jump times, and an increase in the amount of time that the ball spent in the air as it travelled to the basket after being released from the shooter's hand. These behavioral changes were accompanied by an overall decline in shooting accuracy of over 20%. Defended shots also tended to elicit greater amounts of movement variability which, when interpreted in conjunction with the other findings, suggests that participants were attempting to adapt their movements to accommodate for the changing demands of the performance environment. Comparisons across different shot types revealed that the influence of the defender was generally context and task dependent.ConclusionsThe results have important implications for representative task design, and highlight how the manipulation of key information sources can have a marked effect upon behavioral responses.     

Compensatory Coordination of Release Parameters in a Throwing Task

The consistency and coordination of release parameters in ball-throwing movements were investigated. The authors used a newly developed index of coordination for release parameters (ICRP) that quantifies the degree of improvement of performance consistency caused by compensatory relationships among parameters (i.e., not caused by consistency of parameters). Eight participants practiced for 150 trials, with the nondominant hand, a ball-throwing task aimed at a stationary target. The magnitude of the ball-release velocity vector, among release parameters, as well as the performance was found to become consistent with practice. The ICRP score suggested that the release parameters were complementarily coordinated with one another, and that the coordination improved with practice. Those results indicate that compensatory relationships among varying release parameters contribute to reducing the variability of performance in a ball-throwing task whose goal is accuracy.     

Qualitative and quantitative change in the dynamics of motor learning

The experiments examined qualitative and quantitative changes in the dynamics of learning a novel motor skill (roller ball task) as a function of the manipulation of a control parameter (initial ball speed). The focus was on the relation between the rates of change in performance over practice time and the changing time scales of the evolving attractor dynamic. Results showed 3 different learning patterns to the changes in the dynamics as a function of practice that were mediated by the initial ball speed. Only participants who learned the task showed a bifurcation in coordination mode that was preceded by enhanced performance variability. The observed multiple time scales to motor learning are interpreted as the products of the dynamical stability and instability realized from (a) the continually evolving landscape dynamics due to bifurcations between attractor organization and (b) the transient phenomena associated with moving toward and away from fixed-point dynamics.     

Compensatory coordination of release parameters in a throwing task

The consistency and coordination of release parameters in ball-throwing movements were investigated. The authors used a newly developed index of coordination for release parameters (ICRP) that quantifies the degree of improvement of performance consistency caused by compensatory relationships among parameters (i.e., not caused by consistency of parameters). Eight participants practiced for 150 trials, with the nondominant hand, a ball-throwing task aimed at a stationary target. The magnitude of the ball-release velocity vector, among release parameters, as well as the performance was found to become consistent with practice. The ICRP score suggested that the release parameters were complementarily coordinated with one another, and that the coordination improved with practice. Those results indicate that compensatory relationships among varying release parameters contribute to reducing the variability of performance in a ball-throwing task whose goal is accuracy.     

The influence of ball-swing on the timing and coordination of a natural interceptive task

Successful interception relies on the use of perceptual information to accurately guide an efficient movement strategy that allows performers to be placed at the right place at the right time. Although previous studies have highlighted the differences in the timing and coordination of movement that underpin interceptive expertise, very little is known about how these movement patterns are adapted when intercepting targets that follow a curvilinear flight-path. The aim of this study was to examine how curvilinear ball-trajectories influence movement patterns when intercepting a fast-moving target. Movement timing and coordination was examined when four groups of cricket batters, who differed in their skill level and/or age, hit targets that followed straight or curvilinear flight-paths. The results revealed that when compared to hitting straight trials, (i) mixing straight with curvilinear trials altered movement coordination and when the ball was hit, (ii) curvilinear trajectories reduced interceptive performance and significantly delayed the timing of all kinematic moments, but there were (iii) larger decrease in performance when the ball swung away from (rather than in towards) the performer. Movement coordination differed between skill but not age groups, suggesting that skill-appropriate movement patterns that are apparent in adults may have fully emerged by late adolescence.     

An especial skill: Support for a learned parameters hypothesis

We tested the ‘learned parameters’ hypothesis as an explanation of the ‘especial skill effect’. Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11-19 ft) with a regular and heavy weight basketball. As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the ‘especial skill effect’. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the ‘learned parameters’ hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs.     

Self-organized criticality and learning a new coordination task

The purpose of this study was to investigate the hypothesis that a self-organized criticality (SOC) practice condition would have a higher improvement rate in performance outcome than a typical progressive difficulty of practice regimen. The roller ball task was used where participants undergo a phase transition from failure to successful performance after sufficient practice. The findings from two experiments showed that the SOC condition had the fastest rate of improvement and the highest performance success level. The success probability in the SOC practice regime was close to the theoretically predicted value of 50%. It appears that the SOC practice condition - by scaling task difficulty to skill level in a self-controlled adaptive strategy - facilitates the learning of new movement coordination pattern by keeping the participant close to the parameter region of the transition of the movement dynamics.     

Catching With Both Hands: An Evaluation of Neural Cross-Talk and Coordinative Structure Models of Bimanual Coordination

Kelso, Southard, and Goodman (1979) and Marteniuk and MacKenzie (1980) have each proposed a different theoretical model for bimanual coordination. In the model of Kelso et al., a close temporal relationship between the hands in a bimanual task is predicted, even when each hand is required to move different distances. In Marteniuk and MacKenzie's model, separate motor commands are issued so that each limb will arrive simultaneously at the specified movement endpoint, leading to low temporal associations between limbs. In most previous work on bimanual coordination, manual aiming tasks with differing constraints have been used by subjects in individual studies. In this study, the usefulness of existing models for predicting performance in a real-world catching task in which the required movement pattern was constrained by ball flight characteristics was examined. E1even university students caught tennis balls with both hands in the following 3 conditions: Condition 1. Ball projected to the right shoulder area (left hand moved a greater distance than the right); Condition 2. Ball projected to center of the chest area, (both hands moved same distance); and Condition 3. Ball projected to left shoulder area (right hand moved a greater distance). Kinematic data (time to peak velocity, movement initiation time) indicating significant cross-correlations between the left and right limbs in all 3 conditions concurred with the data of Kelso et al. (1979) on manual aiming. Timing appeared to be an essential variable coordinating bimanual interceptive actions. Although the limbs moved at different speeds when each was required to move different distances, times to peak velocity showed strong associations, suggesting the presence of a coordinative structure.     

Aiming at a far target under different viewing conditions: visual control in basketball jump shooting

Most research on visual search in aiming at far targets assumes preprogrammed motor control implying that relevant visual information is detected prior to the final shooting or throwing movements. Eye movement data indirectly support this claim for stationary tasks. Using the basketball jump shot as experimental task we investigated whether in dynamic tasks in which the target can be seen until ball release, continuous, instead of preprogrammed, motor control is possible. We tested this with the temporal occlusion paradigm: 10 expert shooters took shots under four viewing conditions, namely, no vision, full vision, early vision (vision occluded during the final +/-350 ms before ball release), and late vision (vision occluded until these final +/-350 ms). Late-vision shooting appeared to be as good as shooting with full vision while early-vision performance was severely impaired. The results imply that the final shooting movements were controlled by continuous detection and use of visual information until ball release. The data further suggest that visual and movement control of aiming at a far target develop in close correspondence with the style of execution.     

Stabilization of head and eyes on target as a factor in successful basketball shooting

This study was undertaken to investigate the role of the head position relative to the target in the programming of directional aiming while the body is in movement. The present series of experiments focused on the relationship between time of eye and head stabilization on the target and level of expertise of basketball players. Preliminary studies suggested a close relationship between head stabilization on the target and level of skill expertise. Experts and beginners differed significantly with respect to the time required for the eye to achieve fixation on the target, and the time required for the head to obtain fixation on the target. Significant differences were also found for head, and eye-head stabilization parameters between conditions of success and failure. The results clearly demonstrate that the efficiency of head and eyes stabilization on target has a strong influence on the success of shooting.     

Effects of postural instability on the coordination between posture and arm reaching

Reaching from standing requires adjustments of hand movement and posture, which are assured by redundant kinematic degrees of freedom. However, the increased demand for postural adjustments may interfere with the stability of reaching. The objective of this study was to investigate the effect of postural instability on the use of kinematic redundancy to stabilize the finger and center-of-mass trajectories during reaching from standing in healthy adults. Sixteen healthy young adults performed reaching movements from standing with and without postural instability induced by small base-of-support. The three-dimensional positions of 48 markers were recorded at 100 Hz. The uncontrolled manifold (UCM) analysis was performed separately with the finger and center-of-mass positions being the performance variables, and joint angles being the elemental variables. ΔV, the normalized difference between the variance in joint angle that does not affect task performance (V_UCM) and the variance that does affect task performance (V_ORT), was calculated separately for finger (ΔV_EP) and center-of-mass (ΔV_COM) positions, and was compared between stable and unstable base-of-support conditions. ΔV_EP decreased after movement onset and reached its minimum value at around 30–50% of the normalized movement time, and increased until movement offset, while ΔV_COM remained stable. At 60%–100% normalized movement time, ΔV_EP was significantly reduced in the unstable base-of-support, compared to the stable base-of-support condition. ΔV_COM remained similar between the two conditions. At movement offset, ΔV_EP was significantly reduced in the unstable base-of-support, compared to the stable base-of-support condition, and was associated with a substantial increase in V_ORT. Postural instability might reduce the ability to use kinematic redundancy to stabilize the reaching movement. The central nervous system may prioritize the maintenance of postural stability over focal movement when postural stability is challenged.     

Catching With Both Hands: An Evaluation of Neural Cross-Talk and Coordinative Structure Models of Bimanual Coordination

Kelso, Southard, and Goodman (1979) and Marteniuk and MacKenzie (1980) have each proposed a different theoretical model for bimanual coordination. In the model of Kelso et al., a close temporal relationship between the hands in a bimanual task is predicted, even when each hand is required to move different distances. In Marteniuk and MacKenzie's model, separate motor commands are issued so that each limb will arrive simultaneously at the specified movement endpoint, leading to low temporal associations between limbs. In most previous work on bimanual coordination, manual aiming tasks with differing constraints have been used by subjects in individual studies. In this study, the usefulness of existing models for predicting performance in a real-world catching task in which the required movement pattern was constrained by ball flight characteristics was examined. Eleven university students caught tennis balls with both hands in the following 3 conditions: Condition 1. Ball projected to the right shoulder area (left hand moved a greater distance than the right); Condition 2. Ball projected to center of the chest area, (both hands moved same distance); and Condition 3. Ball projected to left shoulder area (right hand moved a greater distance). Kinematic data (time to peak velocity, movement initiation time) indicating significant cross-correlations between the left and right limbs in all 3 conditions concurred with the data of Kelso et al. (1979) on manual aiming. Timing appeared to be an essential variable coordinating bimanual interceptive actions. Although the limbs moved at different speeds when each was required to move different distances, times to peak velocity showed strong associations, suggesting the presence of a coordinative structure.     

Interpersonal coordination tendencies and perception of visual information for decision-making in futsal

This study investigated how futsal players visually perceived information on angular interpersonal coordination relations, between available sources such as nearest defender, goalkeeper position and ball, when deciding to shoot at goal. Experienced players (n = 180) participated in eighteen, video-recorded futsal matches, during which 32 participants wore an eye tracking device. Forty-five sequences of play were selected and edited from the moment a teammate passed the ball to the shooter, until the moment a shot was undertaken. Independent variables included the angle connecting the shooter to their closest defender and goalkeeper, and it’s rate of change (velocity and variability) during performance. Then eye tracking system (TOBII PRO) was used to examine gaze patterns of shooters during task performance. Findings revealed that: (i) futsal players adapted their gaze patterns differently between key information sources when shooting confirmed as: their closest defender, goalkeeper, ball, and court floor; and (ii), the ball was the information source which was most fixated on, regardless of the characteristics of interpersonal coordination tendencies that emerged when shooting. These findings can be interpreted as evidence of functional perceptual behaviours used to regulate actions needed to ensure precise contact with the ball when shooting at goal. Further, adaptations of fixation patterns, varied between marking defender, goalkeeper, and ball, may provide functional postural orientation to facilitate a successful shot at goal.     

Angular relationships regulate coordination tendencies of performers in attacker–defender dyads in team sports

This study examined the continuous interpersonal interactions of performers in dyadic systems in team sports, as a function of changing information constraints. As a task vehicle, we investigated how attackers attained success in 1v1 sub-phases of basketball by exploring angular relations with immediate opponents and the basket. We hypothesized that angular relations would convey information for the attackers to dribble past defenders. Four basketball players performed as an attacker and defender in 1v1 sub-phases of basketball, in which the co-positioning and orientation of participants relative to the basket was manipulated. After video recording performance behaviors, we digitized participant movement displacement trajectories and categorized trials as successful or unsuccessful (from the attackers’ viewpoint). Results revealed that, to successfully dribble past a defender, attackers tended to explore the left hand side of the space by defenders by increasing their angular velocity and decreasing their angular variability, especially in the center of the court. Interpersonal interactions and goal-achievement in attacker–defender dyads appear to have been constrained by the angular relations sustained between participants relative to the scoring target. Results revealed the functionality of exploratory behaviors of participants attempting re-align spatial relations with an opponent in 1v1 sub-phases of team games.