Coordination and its acquisition in a multi-articular lower limb interceptive task

Human movement is mostly multi-articular in nature, involving numerous joint movement possibilities. This complexity in human movement has provided a theoretical challenge for movement scientists to comprehend the underlying processes controlling these joint movements in a functional and goal-directed manner. Although there has been an increase in research on examining coordination in multi-articular actions, it is still in its infancy. The aim of this thesis was to examine the acquisition of coordination of a discrete multi-articular movement action from the theoretical perspective of Dynamical Systems Theory. Specifically, four different studies (comprising Chapters 2, 3, 4 and 5) examined key research questions raised (Chapter 1) about understanding the coordination and control of a lower limb multi-articular interceptive action. The thesis concludes in Chapter 6 with a brief discussion on the key findings and the implications for practitioners in physical education pedagogy relating to a games teaching approach. The empirical work began with an analysis of the variation in coordination as a function of skill (Chapter 2). A discrete multi-articular kicking action with specific task constraints (kicking over a height barrier and to different target positions) was utilised as a research vehicle to examine differences in coordination between three groups of participants: skilled, intermediates and novices. From group analysis, it was determined that skilled and intermediate groups demonstrated a functional coordination mode involving a lower joint involvement at the proximal joints and higher joint involvement at distal joints, mimicking a ‘chip-like action’ in soccer. In contrast, large range of motions in the kicking limb was seen for the novice participants who demonstrated a ‘driving-like action’. Analysis of ball trajectory data confirmed that novice participants were not able to successfully project the ball over the height barrier. Findings from this study demonstrated that joint involvement is dependent on skill level and task constraints rather than a proposed universal ‘reducing to increasing’ involvement of degrees of freedom strategy as suggested by previous research. Functional foot velocity at ball contact to various target positions demonstrated by skilled and intermediate players further highlighted the possibility of using a model of learning focusing on coordination to examine progression through the different stages of learning. Given the findings in Chapter 2 and how averaging group data may mask valuable data at the individual level of analysis, a multiple-single participant design was warranted to examine how intra-participant coordination may differ within the skilled group. In Chapter 3, coordination of skilled players was further investigated to determine if refined differences could be present at the skilled level of performance using the same research design in Chapter 2. From the investigation, although global similarities in terms of the use of a chipping action in projecting the ball was found, differences in foot position for non-kicking foot and centre of mass displacement near ball contact emphasised that even skilled individuals can demonstrate different coordination solutions to meet the same task goal, highlighting the concept of degeneracy in the control and coordination of human movement. Such an observation provided the impetus to further examine coordination changes in novice learners as a function of practice using multiple-single participant analysis (Chapter 4). From the study, individual learners demonstrated different progression trends in terms of joint motion changes while achieving the same task goal. Intra-participant analysis showed how the ball can be projected accurately across the height barrier with both a ‘scooping’ and a ‘chipping’ action. When referenced to a model of learning (Newell, 1985), foot velocity at ball contact was functionally manipulated by the novice participants to target positions with varying height and distance constraints by later stages of learning. It was further suggested that the dynamics of the learner prior to practicing the task could influence the eventual kicking action that emerged. To further investigate learning from a dynamical systems perspective, key features like transitions between preferred movement patterns and role of movement patterns variability in effecting such transitions was examined in Chapter 5. It was determined through the use of cluster analysis procedures that increased movement pattern variability was not a pre-requisite for a transition between preferred movement patterns across participants. Informational and intentional constraints can have a role to play in effecting the search for pathways of change in movement patterns especially in discrete trial-based multi-articular actions. This thesis has contributed novel knowledge regarding examining coordination changes for a selected discrete multi-articular lower limb action. Focusing on investigating changes in coordination has enabled a detailed examination on the process of change with practice and referencing these changes to a model of learning based on concepts in dynamical systems theory. Specifically, a greater understanding on the role of movement pattern variability and transitions between preferred movement patterns using refined cluster analysis procedures was an advancement of previous work in this area of study. In addition, the empirical findings provided theoretical support for a pedagogical approach, Nonlinear Pedagogy, based on key concepts in dynamical systems theory (Chapter 6). Nonlinear Pedagogy can help inform practitioners on the relevance of manipulating task, environmental and performer constraints to enable functional movement solutions to surface in a learning situation without the need to provide explicit and the delivery of a top-down teaching approach commonly observed in skills teaching. The relevance of Nonlinear Pedagogy was further emphasised in this thesis with a discussion on a games teaching approach that is increasingly popular in Physical Education. Future studies should continue to examine coordination in multi-articular actions to provide theoretical, experimental and practical implications for understanding human movement