A Developmental Approach to Sport Expertise

This chapter examines the personal and contextual factors of youth sport that affect sport expertise and developmental outcomes. The developmental model of sport participation (DMSP) is used as a comprehensive framework that outlines different pathways of involvement in sport. Activities and contexts that promote continued sport participation and expert performance are discussed as the building blocks of all effective youth sport programs. This chapter provides evidence that performance in sport, participation, and psychological development should be considered as a whole instead of as separate entities by youth sport programmers. Adults in youth sports (i.e. coaches, parents, sport psychologists, administrators) must consider the differing implications of concepts such as deliberate play, deliberate practice, sampling, specialization, and program structure at different stages of an athlete's talent development. Seven postulates are presented regarding important transitions in youth sport and the role that sampling and deliberate play, as opposed to specialization and deliberate practice, can have during the childhood in promoting continued participation and elite performance in sport

EVIDENCE FOR MECHANICAL STRAINS INFLUENCE IN OSTEOPHYTE DEVELOPMENT

Purpose: Osteophytes are osteo-cartilaginous metaplastic tissue outgrowths of bone capped by cartilage usually found in degenerative and inflammatory joint disease. The presence and degree of maturity of osteophytes, along with joint space narrowing, are the main radiographic criteria for diagnosis and grading osteoarthritis (OA). Although osteophytes are known for being anatomic signs of advanced OA, they can occur in non-symptomatic joints, in joints with no other observable alterations, and in early stage OA. It remains unclear if they develop from molecular, physiological and/or mechanical stimuli. We hypothesized that mechanical strains play a role in osteophyte development. The overall objective of this thesis was to find evidence that osteophytes are influenced by mechanical strains. Methods: The first project was to develop a mechanically-induced osteophyte animal model. One single impact load that was reported to induce moderate joint damage was applied to the periosteum of the rat knee. Animals were sacrificed at four time points to characterize the evolution of damaged tissue and the joint by histology. A second study using human mature hip osteophytes was conducted to evaluate if mature osteophyte presented histological signs of proliferating and developmental processes. The histological characterization of mature osteophyte was used to compare findings of the mechanically-induced osteophyte in the animal model to validate the use of this rodent model in studying some aspect of osteophyte development of human. Lastly, a detailed three-dimensional (3D) radiological morphometric analysis was performed on microscopic computed tomography (µCT) scanned femoral heads collected from total hip arthroplasty patients presenting mature hip osteophytes. Quantitative morphometric measures of osteophytes internal structure was compared to three regions of the femoral head of known quality of organisation and mechanical constraint. Results and Conclusion: Osteophyte can be mechanically induced by a single load impact to the joint periosteum, indicating that a moderate trauma to the periosteal layer of the joint may play a role in osteophyte development. Mature osteophytes have proliferation, developing and remodelling zones and have trabecular structures. Mechanically-induced osteophytes and mature osteophytes presented similar histological composition. Mature osteophytes have organized internal structure. These results provide evidence that mechanical strain can influence osteophyte development.