Changes in running economy following downhill running

In this study, we examined the time course of changes in running economy following a 30-min downhill (-15%) run at 70% peak aerobic power (VO2peak). Ten young men performed level running at 65, 75, and 85% VO2peak (5 min for each intensity) before, immediately after, and 1 - 5 days after the downhill run, at which times oxygen consumption (VO2), minute ventilation, the respiratory exchange ratio (RER), heart rate, ratings of perceived exertion (RPE), and blood lactate concentration were measured. Stride length, stride frequency, and range of motion of the ankle, knee, and hip joints during the level runs were analysed using high-speed (120-Hz) video images. Downhill running induced reductions (7 - 21%, P < 0.05) in maximal isometric strength of the knee extensors, three- to six-fold increases in plasma creatine kinase activity and myoglobin concentration, and muscle soreness for 4 days after the downhill run. Oxygen consumption increased (4 - 7%, P < 0.05) immediately to 3 days after downhill running. There were also increases (P < 0.05) in heart rate, minute ventilation, RER, RPE, blood lactate concentration, and stride frequency, as well as reductions in stride length and range of motion of the ankle and knee. The results suggest that changes in running form and compromised muscle function due to muscle damage contribute to the reduction in running economy for 3 days after downhill running.     

Positional matters: school leaders engaging with national equity agendas

ABSTRACT

This paper claims a central role for school leaders (principals or head-teachers) in the enactment of social justice policy in schools, who act as key agents or ‘gate keepers’ for what counts as social justice in their contexts of practice. Social justice means different things in different contexts depending on where leaders – who use policy as an opportunity to advance what they think is achievable within the limits of available resources – are positioned in the field and how that defines their stances. Drawing on qualitative data generated through in-depth interviews with ten secondary school principals in two Australian cities, the paper analyses the engagement of school leaders with nationally prescribed equity-related policies. Our analysis shows that, depending on the institutional ethos and resources of schools and their own social justice dispositions, school leaders tend to take different stances towards nationally defined equity agendas. Their responses range from compliance to compromise to contest. The paper suggests that doing social justice in schools can never be unilateral, as policy documents suppose, but is characterised by context-informed policy translation, mediated by a range of interactive forces and interests.     

Uncontrollable Mental Imagery: Graphical Connections Between A Function And Its Derivative

The view that imagery might be a disadvantage on certain tasks might surprise some mathematics educators who contend that a learner's conceptual understanding is increased whenever visual imagery is used. One of the limitations of imagery found in the literature comes to bear on a unique aspect of mathematics teaching and learning. This is the notion of an uncontrollable image, which may persist, thereby preventing the opening up of more fruitful avenues of thought, a difficulty which is particularly acute if the image is vivid. Although one calculus student's images supported high levels of mathematical functioning, occasionally his vivid images became uncontrollable, and the power of these images did more to obscure than to explain. This type of imagery can be a major hindrance in constructing meaning for mathematical concepts — contrary to the panacea view of imagery which is sometimes expressed.This revised version was published online in September 2005 with corrections to the Cover Date.     

Early Relationship Quality From Home to School: A Longitudinal Study

The aim of this investigation was to examine the role of social relationships in the home as predictors of social functioning in the first years of school. Longitudinal data gathered on 156 children from urban, low-income families were used to examine the unique contributions of mother-child attachment classification at ages 1 and 2 years, the child's relationship with another adult caregiver, the child's closeness to a sibling, and the child's status in the family relative to siblings between ages 3 and 4 years, to teacher reports of their own relationship to the child and the child's social skills in the classroom and peer relations. The role of family-based relationships as possible protective factors for children at social or demographic risk for problems in school was also tested. Results indicate that quality of different family relationships provides relatively independent and complementary information about early social functioning in school, with more limited evidence for compensatory or protective processes at work.