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Constraints on the complete optimization of human motion

TL;DR: In this article, it is argued that complex mathematical models are superior to simple mathematical models as they enable basic mechanical insights to be made and individual-specific optimal movement solutions to be identified.
Abstract: In sport and exercise biomechanics, forward dynamics analyses or simulations have frequently been used in attempts to establish optimal techniques for performance of a wide range of motor activities. However, the accuracy and validity of these simulations is largely dependent on the complexity of the mathematical model used to represent the neuromusculoskeletal system. It could be argued that complex mathematical models are superior to simple mathematical models as they enable basic mechanical insights to be made and individual-specific optimal movement solutions to be identified. Contrary to some claims in the literature, however, we suggest that it is currently not possible to identify the complete optimal solution for a given motor activity. For a complete optimization of human motion, dynamical systems theory implies that mathematical models must incorporate a much wider range of organismic, environmental and task constraints. These ideas encapsulate why sports medicine specialists need to adopt more individualized clinical assessment procedures in interpreting why performers' movement patterns may differ.
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01 Jan 2013
TL;DR: In this paper, the authors identify key properties of expertise in sport predicated on the performer-environment relationship and highlight the weaknesses of traditional approaches to expert performance, which uniquely focus on the individual and the environment separately, highlighted by an ecological dynamics perspective.
Abstract: This paper identifies key properties of expertise in sport predicated on the performer-environment relationship. Weaknesses of traditional approaches to expert performance, which uniquely focus on the performer and the environment separately, are highlighted by an ecological dynamics perspective. Key properties of expert movement systems include 'multi- and meta-stability', 'adaptive variability', 'redundancy', 'degeneracy' and the 'attunement to affordances'. Empirical research on these expert system properties indicates that skill acquisition does not emerge from the internal representation of declarative and procedural knowledge, or the imitation of expert behaviours to linearly reduce a perceived 'gap' separating movements of beginners and a putative expert model. Rather, expert performance corresponds with the ongoing co-adaptation of an individual's behaviours to dynamically changing, interacting constraints, individually perceived and encountered. The functional role of adaptive movement variability is essential to expert performance in many different sports (involving individuals and teams; ball games and outdoor activities; land and aquatic environments). These key properties signify that, in sport performance, although basic movement patterns need to be acquired by developing athletes, there exists no ideal movement template towards which all learners should aspire, since relatively unique functional movement solutions emerge from the interaction of key constraints.

175 citations

Journal Article
TL;DR: A Morphological Perspective on the Origin and Evolution of Movement Patterns and the Development of Motor Skill Acquisition in Children is presented.
Abstract: Section 1 Motor Skill Acquisition in Children: Perspectives and Problems.- A Perspective on Motor Development.- Some Problems in Explaining the Origins of Movement Control.- A Knowledge-Based Approach to Motor Skill Acquisition.- Section 2 Prenatal Onset of Motor Patterns.- Prenatal Motor Development.- The Maturation and Development of Fetal Motor Patterns.- Section 3 Development of Coordination.- Development of Coordinated Movement: Dynamic, Relational and Multileveled Perspectives.- Development of Coordinated Movement: Implications for Early Human Development.- Issues in the Study of Human Motor Skill Development: A Reaction to John Fentress.- Section 4 Perception and Action.- Perception and Representation in the Guidance of Spatially Coordinated Behaviour.- Movement Invariances in Culture Specific Skills.- The Emergence of Manual Skills.- Perception-Action Coupling in the Young Infant.- The Perception-Action Perspective: A Commentary on von Hofsten.- Section 5 The Development of Intersubjectivity.- Development of Intersubjective Motor Control in Infants.- Subjective Comments on the Development of Intersubjectivity.- Section 6 Establishing a Base for Perception and Action.- Establishing a Frame of Reference for Action.- Contribution of Head-Movement to the Accuracy of Directional Aiming and Coincidence-Timing Tasks.- Visuo-Manual Coordination from 6 to 10: Specification, Control and Evaluation of Direction and Amplitude Parameters of Movement.- Section 7 Cognition and Action.- Constraints on the Development of Coordination.- Motor Coordination: Constraints and Cognition a Reaction to K.M. Newell.- Action and Cognition Cognitive and Motor Skills in a Developmental Perspective.- Relating Cognition and Action: Reaction to Mounoud.- Cognition and Action: A Reply to Mounoud.- Section 8 Contribution of the Neurosciences to an Understanding of Motor Development.- Development and Acquisition of Motor Skills: A Challenging Prospect for Neuroscience.- The Contribution of the Neurosciences to Understanding the Development of Reaching.- Section 9 Epilogue.- A Morphological Perspective on the Origin and Evolution of Movement Patterns.

56 citations

Journal Article
TL;DR: In this article, a multiple case study approach was adopted to explore the degenerate movement behavior displayed by three male amputees walking overground at a self-selected preferred pace and when this speed was enforced on a treadmill (50 stride cycles per condition).
Abstract: There has been no direct attempt to evaluate whether gait performed overground and on a treadmill is the same for lower limb amputees. A multiple case study approach was adopted to explore the degenerate movement behavior displayed by three male amputees. Participants walked overground at a self-selected preferred pace and when this speed was enforced on a treadmill (50 stride cycles per condition). The extremities of motion (i.e., maximum flexion) for the hip and knee joints differed between conditions (0.2–3.8°). For two participants, the temporal asymmetry of gait was reduced on the treadmill. Initial data suggest that research on amputees simulating overground walking on a treadmill might need to be interpreted with some caution.

13 citations

References
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Book
01 Jan 1967

6,041 citations

01 Jan 1984
TL;DR: The adaptationist programme is faulted for its failure to distinguish current utility from reasons for origin, and Darwin’s own pluralistic approach to identifying the agents of evolutionary change is supported.
Abstract: An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an organism into unitary ‘traits’ and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin’s own pluralistic approach to identifying the agents of evolutionary change.

5,926 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a theory of self-organization of behaviour in the human brain, focusing on the brain's ability to learn and adapt to the external world.
Abstract: Part 1 How nature handles complexity: what is a pattern? kinds of patterns principles of dynamic pattern formation the messages of self-organized patterns new laws to be expected in the organism matters of mind and matter the mind revealed? or, what this book's about. Part 2 Self-organization of behaviour - the basic picture: some historical remarks about the science of psychology are actions self-organized? if so, how? from synergies to synergetics requirements of a theory of self-organized behaviour. Part 3 Self-organization of behaviour - first steps of generalization: Hubris tempered? on Harvard horses and Russian cats coordination between components of an organism coordination between organisms on coupling. Part 4 Extending the basic picture - breaking away: relative coordination relative coordination explained absolute and relative coordination unified related models - fireflies, lampreys, and lasers instability and the nature of life - the intermittency mechanism exposed postscript. Part 5 Intentional dynamics: goal-directness in biology the second cornerstone of biological self-organization - informational specificity intentional behaviourial change related views - termites, predator-prey cycles, and quantum mechanics summing up. Part 6 Learning dynamics: issues in learning the main concepts the 'seagull effect' - competition and cooperation questions of learning transfer and generalization - symmetry again behaviourial development evolution and morphogenesis summary and conclusions. Part 7 perceptual dynamics: the barrier of meaning - perceptual dynamics I the barrier of meaning - perceptual dynamics II metastability of mind principles of perceiving - calculating, settling, resonating, and twinkling. Part 8 Self-organizing dynamics of the nervous system: microscale events mesoscale events macroscale events extending the basic picture...again postscript on etymology. Part 9 Self-organization of the human brain: prolegomenon obstacles to understanding the brain is not a static machine the 'brain dynamics' approach - fractural dimension spatiotemporal patterns of the brain models of brain behaviour - coupled modes and Sil'nikov chaos summary and conclusions - brain behaviour.

2,486 citations

Journal ArticleDOI
TL;DR: This work has redefined optimality in terms of feedback control laws, and focused on the mechanisms that generate behavior online, allowing researchers to fit previously unrelated concepts and observations into what may become a unified theoretical framework for interpreting motor function.
Abstract: The sensorimotor system is a product of evolution, development, learning and adaptation-which work on different time scales to improve behavioral performance. Consequently, many theories of motor function are based on 'optimal performance': they quantify task goals as cost functions, and apply the sophisticated tools of optimal control theory to obtain detailed behavioral predictions. The resulting models, although not without limitations, have explained more empirical phenomena than any other class. Traditional emphasis has been on optimizing desired movement trajectories while ignoring sensory feedback. Recent work has redefined optimality in terms of feedback control laws, and focused on the mechanisms that generate behavior online. This approach has allowed researchers to fit previously unrelated concepts and observations into what may become a unified theoretical framework for interpreting motor function. At the heart of the framework is the relationship between high-level goals, and the real-time sensorimotor control strategies most suitable for accomplishing those goals.

1,650 citations

Book Chapter
01 Jan 1986

1,625 citations