In the context of comprehensive and coordinated approaches to school health, academic classrooms have gained attention as a promising setting for increasing physical activity and reducing sedentary time among children. The aims of this paper are to review the rationale and knowledge base related to movement integration in academic classrooms, consider the practical applications of current knowledge to interventions and teacher education, and suggest directions for future research. Specifically, this paper (i) situates movement integration amid policy and research related to children's health and the school as a health-promoting environment; (ii) highlights the benefits of movement integration; (iii) summarizes movement integration programs and interventions; (iv) examines factors associated with classroom teachers' movement integration; (v) offers strategies for translating research to practice and (vi) forwards recommendations for future inquiry related to the effectiveness and sustainability of efforts to integrate movement into classroom routines. This paper provides a comprehensive resource for developing state-of-the-art initiatives to maximize children's movement in academic classrooms as a key strategy for important goals in both education and public health.

The existence of soluble organic forms of N in rain and drainage waters has been known for many years, but these have not been generally regarded as significant pools of N in agricultural soils. We review the size and function of both soluble organic N extracted from soils (SON) and dissolved organic N present in soil solution and drainage waters (DON) in arable agricultural soils. SON is of the same order of magnitude as mineral N and of equal size in many cases; 20-30 kg SON-N ha -1 is present in a wide range of arable agricultural soils from England. Its dynamics are affected by mineralisation, immobilisation, leaching and plant uptake in the same way as those of mineral N, but its pool size is more constant than that of mineral N. DON can be sampled from soil solution using suction cups and collected in drainage waters. Significant amounts of DON are leached, but this comprises only about one-tenth of the SON extracted from the same soil. Leached DON may take with it nutrients, chelated or complexed metals and pesticides. SON/DON is clearly an important pool in N transformations and plant uptake, but there are still many gaps in our understanding.

BackgroundPhysical activity interventions targeting children and adolescents (≤18 years) often focus on complex intra- and inter-personal behavioral constructs, social-ecological frameworks, or some combination of both. Recently published meta-analytical reviews and large-scale randomized controlled trials have demonstrated that these intervention approaches have largely produced minimal or no improvements in young people’s physical activity levels.DiscussionIn this paper, we propose that the main reason for previous studies’ limited effects is that fundamental mechanisms that lead to change in youth physical activity have often been overlooked or misunderstood. Evidence from observational and experimental studies is presented to support the development of a new theory positing that the primary mechanisms of change in many youth physical activity interventions are approaches that fall into one of the following three categories: (a) the expansion of opportunities for youth to be active by the inclusion of a new occasion to be active, (b) the extension of an existing physical activity opportunity by increasing the amount of time allocated for that opportunity, and/or (c) the enhancement of existing physical activity opportunities through strategies designed to increase physical activity above routine practice. Their application and considerations for intervention design and interpretation are presented.SummaryThe utility of these mechanisms, referred to as the Theory of Expanded, Extended, and Enhanced Opportunities (TEO), is demonstrated in their parsimony, logical appeal, support with empirical evidence, and the direct and immediate application to numerous settings and contexts. The TEO offers a new way to understand youth physical activity behaviors and provides a common taxonomy by which interventionists can identify appropriate targets for interventions across different settings and contexts. We believe the formalization of the TEO concepts will propel them to the forefront in the design of future intervention studies and through their use, lead to a greater impact on youth activity behaviors than what has been demonstrated in previous studies.

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S U M M A R YComparisons were made between 1988 and 1991 to evaluate three methods of estimating thc leaching of mineral nitrogen (N) from unstructured freely draining sandy loam and loamy sand soils. The studies compared the drainage patterns and quantities of N (almost cxclusively nitrate) leachcd from monolith lysimeters with those estimated from ceramic suction cups and soil core extracts. The latter two methods gave direct measurements of the mineral N concentrations in drainage, but required an estimate of the drainage volume calculated from meteorological observations and evapotranspiration equations to give total N leached. A bromide tracer was also used to confirm conclusions from nitrate leaching studies. There was a delay in the onset of drainage from free draining lysinieters because they lack the subsoil matric potential offield soils. However, total annual drainage measured by lysimctcrs or calculated from meteorological observations was similar, providing that return to field capacity was correctly identified in the field soil. During the first year thcrc wcrc discrepancies bctwccn methods which were attributcd to soil disturbance during lysimetcr and/or ceramic cup installation. In the second and third years of the experiment, estimates of N leaching losses using the Iysimeters and ceramic cups wcre in good agreement. Nitrate concentrations in soil solution at a depth of 130 cm measured from soil core extracts were smaller than found by the othcr methods during the second year and thc peak concentrations wcre significantly different ( P < 0.05). However, total overwinter N leached was not significantly different. Thus, while lysimeters and cups can be uscd to quantify leaching losses on unstructured, free draining soils if uscd corrcctly, the use ofsoil core extracts is questionable.