Determination of a Total Body Model of Efficiency Applied to a Rowing Movement in Humans

Efficiency represents the ratio of work done to energy expended. In human movement, it is desirable to maximise the work done or minimise the energy expenditure. Whilst research has examined the efficiency of human movement for the lower and upper body, there is a paucity of research which considers the efficiency of a total body movement. Rowing is a movement which encompasses all parts of the body to generate locomotion and is a useful modality to measure total body efficiency. It was the aim of this research to develop a total body model of efficiency and explore how skill level of participants and assumptions of the modelling process affected the efficiency estimates Three studies were used to develop and evaluate the efficiency model. Firstly, the efficiency of ten healthy males was established using rowing, cycling and arm cranking. The model included internal work from motion capture and efficiency estimates were comparable to published literature, indicating the suitability of the model to estimate efficiency. Secondly, the model was developed to include a multi-segmented trunk and twelve novice and twelve skilled participants were assessed for efficiency. Whilst the efficiency estimates were similar to published results, novice participants were assessed as more efficient. Issues such as the unique physiology of trained rowers and a lack of energy transfers in the model were considered contributing factors. Finally the model was redeveloped to account for energy transfers, where skilled participants had higher efficiency at large workloads. This work presents a novel model for estimating efficiency during a rowing motion. The specific inclusion of energy transfers expands previous knowledge of internal work and efficiency, demonstrating a need to include energy transfers in the assessment of efficiency of a total body action.

The Copenhagen Consensus Conference 2016: children, youth, and physical activity in schools and during leisure time

From 4 to 7 April 2016, 24 researchers from 8 countries and from a variety of academic disciplines gathered in Snekkersten, Denmark, to reach evidence-based consensus about physical activity in children and youth, that is, individuals between 6 and 18 years. Physical activity is an overarching term that consists of many structured and unstructured forms within school and out-of-school-time contexts, including organised sport, physical education, outdoor recreation, motor skill development programmes, recess, and active transportation such as biking and walking. This consensus statement presents the accord on the effects of physical activity on children's and youth's fitness, health, cognitive functioning, engagement, motivation, psychological well-being and social inclusion, as well as presenting educational and physical activity implementation strategies. The consensus was obtained through an iterative process that began with presentation of the state-of-the art in each domain followed by plenary and group discussions. Ultimately, Consensus Conference participants reached agreement on the 21-item consensus statement.

The Effect of Water Consumption on Schoolchildren's Fine Motor Skills, Cognitive Function and Mood

Previous research has suggested that dehydration may have a negative effect on some aspects of mood, cognitive performance and motor skills (Benton, 2011). Furthermore, a large proportion of children arrive at school in a dehydrated state (Baron, Courbebaisse, Lepicard, & Friedlander, 2015). The present work investigated whether supplementing children with water may, as a consequence of reducing dehydration, improve their cognitive performance and motor skills. In studies 1, 2, 3 and 5, it was found that tasks that predominantly tested motor skills, were improved in children who had a drink, compared to those who did not. Furthermore, study 3 showed that this effect was moderated by hydration status. One theoretical explanation for the poorer performance of dehydrated children is that they may lack the neurological resources to sustain their effort and thus performance does not improve over time. In support of this, these studies showed that, when re-hydrated, performance on these tasks improves to the level of non-dehydrated children. Study 2 showed that the number of errors increased in a StopSignal task in children that had high self-rated levels of thirst, compared to low levels: and hydration status did not moderate this effect. A possible explanation for the increased number of errors in children with high self-rated thirst is that the thirst sensation diverts attention away from the task, causing task performance to deteriorate. In study 4, it was observed that there was a large variation in intra-individual and inter-individual hydration scores throughout the day, which was not related to volume drank or levels of thirst. Further studies should use imaging techniques to study brain activity during dehydration and rehydration, and during periods of high thirst, to help to further elucidate the mechanism underlying the negative effect of dehydration on motor performance, and the effect of self-rated thirst on attention.