Le sport est largement conseillé chez les enfants et les adolescents mais a pour inconvénient le développement de blessures musculosquelettiques au niveau des membres et du rachis. Les blessures de surutilisation des membres représentent une part importante des blessures musculo-squelettiques.Cette thèse avait pour but de déterminer s’il existait des différences entre les sports en ce qui concerne l’incidence, la localisation et le diagnostic de blessures de surutilisation des membres chez les enfants et si certains sports étaient des facteurs de risques pour le développement de ces blessures. De plus, elle avait pour but de comparer les résultats obtenus à ceux des adultes.Pour ce faire, deux revues systématiques ont été réalisées, la première pour les enfants et adolescents et la seconde pour les adultes. De plus, une étude prospective réalisée dans une population générale d’enfants a été analysée.Il existence peu d’évidences scientifiques sur l’incidence, les localisations et les diagnostics des blessures de surutilisation dans la littérature. Pour ces deux populations, et pour tous les sports étudiés les blessures de surutilisation affectent plus fréquemment les membres inférieurs. Chez les enfants/adolescents, les blessures affectent en particulier les genoux et la jambe, sans grande différence entre les sports. Alors que chez les adultes des différences apparaissent entre les sports et les zones les plus souvent touchées sont différentes des enfants. Concernant les diagnostics, il n’y a pas de différence entre les sports chez les enfants ; et il n’est pas possible de se prononcer chez les adultes. On note des différences entre les diagnostics retrouvés chez les enfants/adolescents et les adultes.L’étude prospective permet d’obtenir l’incidence des blessures pour neuf sports, et identifie parmi ceux-ci deux sports à risque : le football et le handball. / In youngsters, physical activity has many direct health benefits but can also cause musculoskeletal injuries. Overuse injuries of the extremities represent an important part of all the musculoskeletal injuries that can occur in childhood.The aim of this thesis is to determine if some sports are more likely to expose children and adolescents to a greater risk of developing overuse injuries of the extremities and to investigate if there is difference regarding the diagnosis and the localisation of these injuries between different types of sports. Another aim was to compare these findings with those relating to adults.To achieve this, two systematic reviews have been done, one for youngsters and one for adults, and data from a large prospective study of schoolchildren were analysed.Paucity of relevant information in the literature made it difficult to obtain clear answers to our questions. However, we noticed that, for both population and all sports, overuse injuries more often affected the lower limb. In youngsters, the sites most often affected are the knee, the lower limb and the foot, and this is almost the same for all sports that were studied. In adults the localisation varies for the different sports and is not the same between youngsters and adults. Also the diagnoses do not vary between sports in youngsters ; whereas it was not possible to study this in adults. The diagnoses were different between the two populations studied. The prospective study of the schoolchildren permitted to determine the incidence of overuse injuries reported in children participating in nine different sports and to relate these results to their exposure to these sports (dose-response). Two sports were identified as risk factors: football and handball.

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Title: Muscle activity analysis during the violoncello play Objectives: This thesis focuses on analysing and comparing specific back muscles of a bowing violoncellist. The findings can help understanding pathologic mechanisms and back pain caused by violoncello playing. It may be useful in choosing suitable preventive compensatory exercise as well and for future research. Eventually, the analysis could be applied in playing ergonomics and designing a proper seat. The thesis also aims on evaluating suitability of the chosen measuring method in this branch. Methods: The theoretical part reviews contemporary knowledge about musculoskeletal system disorders linked with violoncello playing. The practical part aims on evaluating data obtained from 3D kinematic analysis and surface EMG of specific back muscles of professional violoncello player during playing. Several conditions are assessed. Results: The experiment has shown that when playing a violoncello there is an asymmetric loading of the back muscles. Loading of specific muscles has is affected by way of bowing, string location and the seat. The experiment was done on a single proband, so these conclusions may not be generally valid. Keywords: violoncello playing, musicians, surface electromyography, 3d kinematic analysis, violoncellists' diseases,...

Although the benefits of exercise are well documented, the risk of injury as a result of exercise is also documented. The undertaking of exercise in the form of sport or dance carries a risk of injury. This risk is increased in the professional ranks where increased intensity of exercise coupled with greater exposure periods are noted. Two published systematic reviews of the literature pertaining to musculoskeletal injuries and pain in dancers (up to 2008) indicated that there are still major scientific limitations and biases in the literature reviewed and indicated the need for explicit criteria on injury definition and methods of injury reporting. The reviews did comment on the evidence that musculoskeletal injury is an important issue for all dancers and that there is preliminary evidence that comprehensive injury prevention and management strategies may reduce injuries. The purpose of this single cohort observational study was to document injury incidence and severity in professional ballet dancers over three years including any changes as a result of changes within their medical management. While it is recognised that a randomised control trial would be advocated for an interventional study, due to the demands of this high performance environment this was not feasible. As such, steps were taken to improve the reporting of findings through the utilisation of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement. To date there are two publications in peer reviewed journals as a result of the data collected in this study. In the absence of international consensus on injury data collection in dance the methodology employed in this study was consistent with the International Consensus Statements on injury data collection from sport. Although the incidence of injuries in Year 1 was lower than that in other sports, the results were higher than other studies that have been reported in dance. The reason for this may be due to the use of a more encompassing injury definition. In response to the data and details obtained through the injury audit process changes in the comprehensive medical management of the dancers were implemented. The pre-participation screening was extended and the individual conditioning programmes were structured using the developed Hybrid Intervention Model. The result of the injury auditing indicated a significant reduction in injury incidence in the Year 2, with a further reduction in Year 3. These findings support the results of the systematic reviews in that there is growing evidence that comprehensive injury prevention and management strategies may reduce injuries in dance and that in the absence of stronger evidence there is a strong recommendation for those charged with caring for professional dancers to implement comprehensive medical management programmes.

Background: The negative side of rugby participation is the danger it presents to health in the form of injuries. Most school coaches, advocates of talent development and selectors put a high priority on implementing programmes to develop bigger, stronger, faster and more skilful rugby players who can excel at their sport. These programmes however, do not place enough emphasis on the prevention of injuries. Aims: The primary aim of the study was to determine the effect of an approved injury prevention programme on the incidence (injuries per 1000 player hours) of n~gbyin juries (overall, intrinsic and extrinsic injuries) of 15- and 16 year-old schoolboys, over a two-year period. A further aim was to measure the effect of an approved injury prevention programme on the selected anthropometric, physical and motor and biomechanical and postural variables of all the groups involved in this study over a period of two years. Originating from these aims, a sub-aim of this study was to use information from this study to provide modifications - if necessary - to the current prevention programme in order for it to be effectively applied at high-school rugby level. Design: A non-equivalent experimental-control group design with multiple post-tests was used for the investigation. Subjects: The subjects were 120 schoolboy rugby players. The subjects came from two secondary schools in the North West province of South Africa. Both schools were schools wit11 a tradition of excellence in rugby. Players who participated in the experimental injury prevention programme were the year 2004, 15- and 16-year old elite A teams. The B teams acted as controls. Method: Players were tested over a two-year period. During each of the two years there were three testing occasions where all players were tested: pre-season, during the mid-season break and at the end of the season. The results of these tests were used to monitor changes in anthropometric, physical and motor and biomechanical and postural variables in various stages of the training programme. At the end of every evaluation, deficits were identified in the performance of all players in the experimental group and the prevention programmes were planned accordingly. Players in the experimental group received exercises to address the specific deficits identified. Rugby injuries were screened and injury data collected through the use of weekly sports. medical clinics. Results: Differences and changes in extrinsic injury incidences in this study could not be attributed to the effect of the prevention programme, and as a result injury trends related to overall injury incidences were inconsistent when the experimental groups were compared to the matching control groups. However, the prevention programme did have a positive effect on the intrinsic injury incidence of both experimental groups during the study period. The following moderate or highly practically significant anthropometric changes occurred when inter-group comparisons for the two year period were considered: triceps skinfold (d=0.8 among 16-year olds), subscapular skinfold (d=0.5 among 16-year olds, midaxillary skinfold (d=1.3 among 15-year olds), calf skinfold (d=1.3 among 16-year olds), humerus breadth (d=1.4 among 15-year olds), femur breadth (d=0.5 among 15-year olds), fat percentage (d=0.5 among 16-year olds) and mesomorphy (d=1.3 among 15-year olds). However, these anthropometric changes may be due to other factors, such as the natural growth phase of boys, rather than the effect of the prevention programme. During the inter-group comparisons of physical and motor components, moderately or highly practically significant improvements were recorded in the vertical jump (d=0.8 for 15-year olds and d=1.5 for 16year olds), bleep (d=0.7 for 16-year olds), pull-ups (d=0.6 for 15-year olds) and push-up tests (d=1.5 for 15-year olds and d=1.1 for 16 year-olds) of the experimental groups considering the total two year period. From the results it was clear that in practice, the prevention programme significantly improved only four of the 11 physical and motor components over the two-year period and that these improvements often occurred in only one of the age groups involved. The inter-group comparison of biomechanical and postural variables revealed numerous moderately and highly practically significant improvements in both age groups. over the total two-year period. All in all the prevention p r o v e provided the experimental groups with a more balanced (closer to ideal) dynamic mobility, core stability and postural symmetry. Conclusion: It could be concluded that the present prevention programme did not have a practically significant effect on the incidence of overall rugby injuries and extrinsic rugby injuries of 15- and 16-year old schoolboys over a two-year period. However, in practice, the prevention programme did have a significantly positive effect on the incidence of intrinsic rugby injuries of 15- and 16-year old schoolboys over a period of two years. It could be concluded that the prevention programme did not have a practically significant effect on the anthropometric components of 15- and 16-year old schoolboys over a two-year period. Seeing that the prevention programme had a moderately or highly practically significantly effect on only four of 11 physical-and-motor components over the two-year period, and that these improvements often occurred in only one of the age groups involved, it could be concluded that the prevention programme did not significantly affect the physical and motor variables of 15- and 16-year old schoolboys over a two-year period. Finally the conclusion could be drawn that in practice the prevention programme significantly improved the biomechanical and postural variables over a period of two years. This improvement in biomechanical and postural status may be responsible for the decrease in intrinsic injury incidence. Information from this study was used to provide modifications to the tested prevention programme in order for it to be effectively applied at high school rugby level. / Thesis (Ph.D. (Movement Science Education))--North-West University, Potchefstroom Campus, 2006

Thesis (Ph.D. (Movement Science Education))--North-West University, Potchefstroom Campus, 2006.

Background: Achilles tendinopathy is a common clinical syndrome of chronic Achilles tendon pain combined with thickening of the tendon and impaired tendon function. Tendinopathy is often, but not always, induced by mechanical overload, and is frequently accompanied by abnormalities at the tissue level, such as hypercellularity and angiogenesis, in which case the condition is called tendinosis. In tendinosis, there are no signs of intratendinous inflammation, but occasionally increased apoptosis is observed. Tendinosis is often hard to treat and its pathogenesis is still not clear. Recently, a new hypothesis has gained support, suggesting a biochemical model based on the presence of a non-neuronal production of classically neuronal signal substances by the primary tendon cells (tenocytes) in tendinosis. The possible functional importance of these signal substances in tendons is unknown and needs to be studied. In particular, the neuropeptide substance P (SP) and catecholamines are of interest in this regard, since these substances have been found to be up-regulated in tendinosis. As both SP and catecholamines are known to exert effects in other tissues resulting in changes similar to those characteristic of tendinosis, it is possible that they have a role in tendinosis development. It is furthermore unknown what elicits the increased intratendinous neuropeptide production in tendinosis, but given that tendon overload is a prominent riskfactor, it is possible that mechanical stimuli are involved. The hypothesis of this thesis work was that intratendinous production of SP is up-regulated in response to load of Achilles tendons/tenocytes, and thatstimulation of the preferred SP receptor, the neurokinin-1 receptor (NK-1 R), aswell as stimulation of the catecholamine α2 adrenoreceptors, contribute to the hypercellularity seen in tendinosis, via increased proliferation and/or decreased apoptosis, and that SP stimulates tendon angiogenesis. The purpose of the studies was to test this hypothesis. To achieve this, two model systems were used: One in vivo (rabbit Achilles tendon overload model of tendinosis) and one in vitro (human primary Achilles tendon cell culture model). Results: In the rabbit Achilles tendon tissue, SP and NK-1 R expression was extensive in the blood vessel walls, but also to some extent seen in the tenocytes. Quantification of endogenously produced SP in vivo confirmed intratendinous production of the peptide. The production of SP by human tendon cells in vitro was furthermore demonstrated. The catecholamine synthesizing enzyme tyrosine hydroxylase (TH), as well as the α2A adrenoreceptor (α2A AR), were detected in the tenocytes, both in vivo in the rabbit tissue and in vitro in the human tendon cells. As a response to mechanical loading in the in vivo model, the intratendinous levels of SP increased, and this elevation was found to precede distinct tendinosis changes. The in vitro model demonstrated the same response to load, i.e. an increased SP expression, but in this case also a decrease in the NK-1 R expression. In the in vivo model, exogenously administered SP, as well as clonidine (an α2 AR agonist), accelerated tenocyte hypercellularity, an effect that was not seen when administrating a specific α2A AR antagonist. Exogenous administration of SP also resulted in intratendinous angiogenesis and paratendinous inflammation. In the in vitro model, both SP and clonidine had proliferative effects on the human tenocytes, specifically mediated via NK-1R and α2A AR, respectively; both of which in turn involved activation/phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2). Exogenously administered SP, in Anti-Fas induced apoptosis of the tenocytes in vitro, confirmed SP to have an anti-apoptotic effect on these cells. This effect was specifically mediated via NK-1 R and the known anti-apoptotic Akt pathway. Conclusions: In summary, this thesis concludes that stimulation of NK-1 R and α2A AR on tenocytes, both in vitro and in vivo, mediates significant cell signalling effects leading to processes known to occur in tendinosis, including hypercellularity. The pathological role of the hypercellularity in tendinosis is still unclear, but it is likely to affect collagen metabolism/turnover and arrangement, and thereby indirectly tendon biomechanical function. Additional evidence is here provided showing that SP not only causes tenocyte proliferation, but also contributes to anti-apoptotic events. Furthermore, it was concluded that SP may be involved in the development of tendinosis, since its production is increased in response to load, preceding tendinosis, and since SP accelerates tendinosis changes, through some mechanistic pathways here delineated. These findings suggest that inhibition of SP, and possibly also catecholamines, could be beneficial in the reconstitution/normalization of tendon structure in tendinosis.

Unilateral exercise can produce certain contralateral strength effects. Deleterious events can be cross-transferred as well, as illustrated by a strict symmetry in some chronic inflammatory diseases. To date, knowledge on the effects of marked overuse of skeletal muscles is limited, and there is largely no information if unilateral overuse affects the contralateral muscles. In view of this, the present study was undertaken to test the hypothesis that unilateral muscle overuse causes alterations in tissue structure and the tachykinin system, with a focus on substance P (SP), not only in the exercised muscles, but also in the contralateral muscles. SP is a well-known neuromodulator that is known to be proinflammatory. An experimental rabbit model with unilateral muscle overuse of the soleus and gastrocnemius muscles caused by exercise via electrical muscle stimulation (E/EMS) was used. In total, 40 rabbits were randomly divided into seven groups of which two groups served as controls. The rabbits were anaesthetized and then set on a “kicking machine” to perform exercise via EMS for 2h every second day. Experimental periods for groups 1-3 were 1, 3 and 6w, respectively, whereas groups 4-6 were exercised for 1w but also subjected to injections in the peritendinous tissue with SP, NaCL, Captopril (C), an ACE inhibitor, and DL-Thiorphan (Th) which inhibits the activity of neural endopeptidase. One group was not subjected to the experiment at all. The day after the last session of E/EMS, the soleus muscle and the gastrocnemius muscle from both legs were collected for analysis. Alterations in muscle structure and the tachykinin system were analyzed with enzyme and immunohistochemical techniques, in situ hybridization and EIA methods. After 1w of E/EMS, focal areas of the exercised muscles contained a mild infiltration of inflammatory cells (myositis) and small morphological changes. After 3 and 6w of E/EMS, distinct myositis and muscle changes were bilaterally present in focal areas of both muscles. The structural changes, which mainly were observed in myositis areas, consisted of increased fiber size variability, split fibers, internal myonuclei, necrotic fibers, fibrosis, fat infiltration, and small fibers containing developmental MyHCs. Bilateral morphological changes, such as loss of axons, were also observed in nerves. In addition, expressions of tachykinin and the SP-preferred receptor, the neurokinin-1 (NK-1R), were bilaterally upregulated in nerve structures and blood vessel walls.  Infiltrating white blood cells exhibited tachykinin–like and NK-1R immunoreactivity. NK-1R immunoreactions were also found in necrotic and regenerating muscle fibers. The concentration of tachykinin (SP) was significantly increased in both soleus and gastrocnemius muscles after E/EMS. There was a significant correlation between the two sides in concentration of tachykinin and in the intensity of tachykinin-like immunoreaction in blood vessel walls. The muscle fiber size and capillary supply of fibers were bilaterally decreased after 3w of EMS. The myositis areas contained an increased number of vessels with a larger size than capillaries, while areas with increased amount of connective tissue contained a very low number of capillaries. A bilateral fiber type shift against a lower proportion of slow MyHCI fibers and higher proportion of fast MyHCII fibers was observed in both muscles. The local injections of C+Th and SP+C+Th led to marked structural changes in the muscle tissue and marked increased NK-1R and tachykinin-like immunoreactivity in the myositis areas and increased tachykinin concentration in the tissue. In conclusion, the repetitive unilateral muscle overuse caused by E/EMS led overtime to muscle injury and myositis. The affected areas contained both degenerative and regenerative alterations in the muscle tissue and nerves, and an upregulation of the tachykinin system. Most interestingly, the changes not only occurred in the exercised side, but also in the homologous contralateral muscles. The tachykinin system appears to be an important factor in the processes of crossover effects.