Overweight and obesity in youth are important public health concerns and are of particular interest because of possible long-term associations with adult weight status and morbidity. The aim of this study was to systematically review the literature and update evidence concerning persistence of childhood overweight. A computerized bibliographical search--restricted to studies with a prospective or retrospective longitudinal design--was conducted. Two authors independently extracted data and assessed the methodological quality of the included studies in four dimensions (i) study population and participation rate; (ii) study attrition; (iii) data collection and (iv) data analysis. Conclusions were based on a rating system of three levels of evidence. A total of 25 publications were selected for inclusion in this review. According to a methodological quality assessment, 13 studies were considered to be of high quality. The majority of these high-quality studies were published after 2001, indicating that recently published data, in particular, provide us with reliable information. All included studies consistently report an increased risk of overweight and obese youth becoming overweight adults, suggesting that the likelihood of persistence of overweight into adulthood is moderate for overweight and obese youth. However, predictive values varied considerably. Limiting aspects with respect to generalizability and methodological issues are discussed.

Notwithstanding the healthy influence of sporting activities on risk factors, in particular those of cardiovascular disease, it is becoming increasingly apparent that sports can present a danger to health in the form of sports injuries. The extent of the sports injury problem calls for preventative action based on the results of epidemiological research. For the interpretation of these facts uniform definitions are needed and limitations of research designs should be known. Measures to prevent sports injuries form part of what is called the 'sequence of prevention'. Firstly the extent of the sports injury problem must be identified and described. Secondly the factors and mechanisms which play a part in the occurrence of sports injuries have to be identified. The third step is to introduce measures that are likely to reduce the future risk and/or severity of sports injuries. This measure should be based on the aetiological factors and the mechanism as identified in the second step. Finally the effect of the measures must be evaluated by repeating the first step. In this review some aspects of the first and second step of the sequence of prevention are discussed. The extent of the sports injury problem is often described by injury incidence and by indicators of the severity of sports injuries. Sports injury incidence should preferably be expressed as the number of sports injuries per exposure time (e.g. per 1000 hours of sports participation) in order to facilitate the comparability of research results. However, one should realise that the outcome of research applying this definition of sports injury incidence is highly dependent on the definitions of 'sports injury' and 'sports participation'. The outcome of such research also depends on the applied research design and research methodology. The incidence of sports injuries depends on: the method used to count injuries (e.g. prospective vs retrospective); the method used to establish the population at risk; and on the representativeness of the sample. Severity of sports injuries can be described on the basis of 6 criteria: the nature of the sports injury; the duration and nature of treatment; sporting time lost; working time lost; permanent damage; and cost. Here also uniform definitions are important and necessary in order to enhance the comparability of research data. In the second step of the 'sequence of prevention' the aetiological factors that play a role in the occurrence of a sports injury have to be identified by epidemiological studies. Epidemiological research on the aetiology of sports injuries requires a conceptual model.(ABSTRACT TRUNCATED AT 400 WORDS)

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