In the literature on inter-limb coordination, the coordination among ‘‘focal’’ body parts (i.e., the two limbs) directly engaged in a pendulum swinging task has been studied by immobilizing other body parts to reduce “noise,” while putting aside questions of how one maintains posture while performing the task. However, in practical performance of musical instruments, for example, performers must coordinate different body parts in sync with the music while maintaining the whole body’s balance. This study demonstrates the effectiveness and necessity of understanding inter-limb coordination in whole-body coordination. Participants were asked to move two pendulums either in sync or alternatively with metronome beeps under two conditions: immobile (fixed forearms) and mobile (forearms not fixed). The explorative analyses focused on whether and how coordinative structures emerged and whether the degree of task achievement differed according to the phase mode, frequency, and mobility conditions. The motion similarity and phase difference between different parts and the pendulums showed that task-specific coordinative structures emerged in both immobile and mobile conditions. In the in-phase mobile condition, the emergent coordinative structure may have improved task achievement, shown by the phase difference between the left and right pendulums. These findings suggest that the global coordinative structure is involved in achieving the local pendulum swinging task.

We explored how practice and actual putting strokes differed between professionals and high-level golf amateurs, and how practice strokes reflected subtle differences in putting distances. We analysed swing amplitude, impact velocity, and acceleration profile of the club-head. The acceleration profiles showed that the motor control pattern of the practice stroke differed from that of the actual stroke. To clarify the effects of different putting distances on the practice stroke and to analyse how much the actual stroke could be explained by the practice stroke, we conducted individual regression analyses. The practice strokes of all participants could be divided into three strategies and five types by the coefficient of determination and the slope. This implies that the purpose of the practice stroke varied among golfers. Most golfers used the individual velocity criteria in their practice strokes, which resulted in different putting distances based on their criteria. Unexpectedly, we found no significant difference in skill level between professionals and high-level amateurs. The results of this study imply that the practice stroke does not duplicate the actual stroke, even for professional golfers with excellent skills. However, most high-level golfers adopted distance-dependent control strategies for slightly different putting distances.

人間は環境の中で適応的に運動をするために，環境の情報を知覚する．一方で身体運動はその環境情報自体に制約され， 規定されてしまうという特徴も有する．このような身体運動と環境情報の相互作用は，人―環境系における動的な秩序形成の 観点から調べられてきた．本稿ではまず，系の時間発展を数理で記述する力学系アプローチを用いて，人間の協調運動が非平 衡開放系における自己組織化の特徴を有することを示した一連の研究を紹介する．さらに同様の現象が，知覚と運動の協調や， 対人間の運動協調にも当てはまることを示した研究を概説し，最後にその発展と展望を述べる．

The current study investigated whether visual coupling between two people producing dance-related movements (requiring whole-body auditory-motor coordination) results in interpersonal entrainment and modulates individual auditory-motor coordination dynamics. Paired participants performed two kinds of coordination tasks - either knee flexion or extension repeatedly with metronome beats (Flexion-on-the-beat and Extension-on-the-beat conditions) while standing face-to-face or back-to-back to manipulate visual interaction. The results indicated that the relative phases between paired participants' movements were closer to 0° and less variable when participants could see each other. In addition, visibility of the partner reduced individual differences in the dynamics of auditory-motor coordination by modulating coordination variability and the frequency of phase transitions from Extension-on-the-beat to Flexion-on-the-beat. Together, these results indicate that visual coupling takes place when paired participants can see each other and leads to interpersonal entrainment during rhythmic auditory-motor coordination, which compensates for individual differences via behavioural assimilation and thus enables individuals to achieve unified and cohesive performances.

It is difficult for humans to apply small amounts of force precisely during motor control. However, experts who have undergone extended training are thought to be able to control low-velocity movement with precision. We investigated the resolution of motor control in golf putting. A total of 10 professional and 10 high-level amateur golfers participated. Putting distances were 0.6-3.3 m, in increments of 0.3 m. We measured the impact velocity and the club-face angle at impact, and the acceleration profile of the downswing. The professionals showed significantly smaller coefficients of variation with respect to impact velocity and smaller root mean square errors in relation to acceleration profiles than did the amateurs. To examine the resolution of motor control for impact velocity, we investigated intra-participant differences in the impact velocity of the club head at two adjacent distances. We found that professionals had higher velocity precision when putting small distance intervals than did amateurs. That is, professionals had higher resolution of low-velocity control than did high-level amateurs. Our results suggest that outstanding performance at a task involves the ability to recognise small distinctions and to produce appropriate movements.

This study investigated whole-body sensorimotor synchronization (SMS) in street dancers and non-dancers. Two kinds of knee bending movement in a standing position to a metronome beat were explored in terms of stability under different movement frequencies: down-movement condition (knee flexion on the beat) and up-movement condition (knee extension on the beat). Analyses of phase relation between movement and beat revealed several distinct differences between the down- and up-movement conditions, and between dancers and non-dancers. In both groups under the up-movement condition, deviation from intended phase relation at higher beat rates, and enhanced fluctuations were observed. The deviation from intended phase relation under up-movement condition, and movement fluctuations were greater in non-dancers than in dancers. Moreover, subjective difficulty rating revealed that both groups felt that the up-movement condition was more difficult at higher beat rates. These findings suggest that down and up movements are two distinguishable coordination modes in whole-body coordination, and that street dancers have superior whole-body SMS ability. © 2010 Elsevier B.V.

While novices who are unfamiliar to a new motor skill typically show variable and unstable movements, highly skilled experts show a stable and accurate performance. These distinct differences in motor control between experts and novices have led researchers to hypothesize that neuromotor noise is reduced in the process of motor skill acquisition. On the other hand, it should be noted that novices’ movements have other characteristics; they are habituated and stereotyped. In this review, we discuss the principles governing spatiotemporal organization of movements in novices and experts while solving specific motor problems under varied conditions, by introducing experimental and theoretical studies that use neurophysiological techniques such as electromyography, functional magnetic resonance imaging, and transcranial magnetic stimulation, and mathematical models such as stochastic and dynamical models. On the basis of the findings from a variety of perceptual-motor skills (e.g., ballthrowing, badminton smash, long-distance running, piano and drum performance, street dance, a popular hand game of rock-paper-scissors, and temporal order judgement task), we argue that the novices’ characteristic movement patterns were organized under specific constraints and typical strategy, without which the variability would increase even more, while experts’ movements were organized with functional and compensatory variability that can drive out erroneous noise variability. We also showed that in a particular type of interlimb coordination, skilled and unskilled movement patterns could be seamlessly described as the time evolution of nonlinear and self-organized dynamical systems, suggesting that the dynamical systems approach is a major candidate for understanding the principle underlying organization of experts’ and novices’ movements.

We review research on athletes' brains based on data obtained using non-invasive neurophysiological and neuroimaging methods
these data pertain to cognitive processing of visual, auditory, and somatosensory (tactile) stimulation as well as to motor processing, including preparation, execution, and imagery. It has been generally accepted that athletes are faster, stronger, able to jump higher, more accurate, more efficient, more consistent, and more automatic in their sports performances than non-athletes. These claims have been substantiated by neuroscientific evidence of the mechanisms underlying the plastic adaptive changes in the neuronal circuits of the brains of athletes. Reinforced neural networks and plastic changes are induced by the acquisition and execution of compound motor skills during extensive daily physical training that requires quick stimulus discrimination, decision making, and specific attention. In addition, it is likely that the manner of neuronal modulation differs among sports. We also discuss several problems that should be addressed in future studies. © 2009 Elsevier B.V.