Maximal-intensity isometric and dynamic exercise performance after eccentric muscle actions

A well-documented observation after eccentric exercise is a reduction in maximal voluntary force. However, little is known about the ability to maintain maximal isometric force or generate and maintain dynamic peak power. These aspects of muscle function were studied in seven participants (5 males, 2 females). Knee extensor isometric strength and rate of fatigue were assessed by a sustained 60 s maximal voluntary contraction at 80 degrees and 40 degrees knee flexion, corresponding to an optimal and a shortened muscle length, respectively. Dynamic peak power and rate of fatigue were assessed during a 30 s Wingate cycle test. Plasma creatine kinase was measured from a fingertip blood sample. These variables were measured before, 1 h after and 1, 2, 3 and 7 days after 100 repetitions of the eccentric phase of the barbell squat exercise (10 sets x 10 reps at 80% concentric one-repetition maximum). Eccentric exercise resulted in elevations in creatine kinase activity above baseline (274+/-109 U x l(-1); mean +/- s(x)) after 1 h (506+/-116 U x l(-1), P < 0.05) and 1 day (808+/-117 U x l(-1), P < 0.05). Isometric strength was reduced (P < 0.05) for 7 days (35% at 1 h, 5% at day 7) and the rate of fatigue was lower (P < 0.05) for 3 days at 80 degrees and for 1 day at 40 degrees. Wingate peak power was reduced to a lesser extent (P < 0.05) than isometric strength at 1 h (13%) and, although the time course of recovery was equal, the two variables differed in their pattern of recovery. Eccentrically exercised muscle was characterized by an inability to generate high force and power, but an improved ability to maintain force and power. Such functional outcomes are consistent with the proposition that type II fibres are selectively recruited or damaged during eccentric exercise.     

Age-related differences in vision and proprioception in a lower limb interceptive task: the effects of skill level and practice

This study examined age-related differences in the role of visual proprioception during a lower limb interceptive action and how this varies as a function of skill and practice. In Experiment 1, skilled and less-skilled 8-, 10-, and 12-year-old boys controlled a soccer ball using their preferred foot under full vision and when sight of the effector was occluded. With the exception of the high-skilled 12-year-olds and low-skilled 8-year-olds, participants showed a decrement in peformance when denied access to visual proprioception. In Experiment 2, the effect of practicing under different informational constraints was examined for 12 year-old boys. Children performed varying amounts of practice under full vision, or in a condition where sight of the foot was occluded, before being transferred to the alternative viewing condition. Participants who practiced under occluded viewing conditions showed greater relative improvement in performance over practice and transfer sessions compared with a full vision control group. Some support is provided for the manipulation of visual informational constraints as an effective pedagogical approach to motor learning.     

Transforming education systems: comparative and critical perspectives on school leadership

The centrality of education in the pursuit of better economic and social prosperity is now well established. The dominance of human capital theory, which provides a strong argument for better education as a key factor in fuelling economic growth, has encouraged policy makers, in various countries, to focus on education reform as a key priority and to borrow policy solutions from other countries. This special edition explores one policy solution in depth. It investigates the preparation and training of school leaders in very different countries and takes a comparative perspective. This article argues that the limitations of standardized strategies are clearly visible when taking a comparative view and, most importantly, that context matters significantly in shaping, defining and explaining differential educational performance.     

Comparing performance: a cross-national investigation into the teaching of mathematics in primary classrooms in England and China

This article presents initial findings from an empirical study of the effectiveness of mathematics teaching (EMT). The article explores the teaching of mathematics in two very different contexts: England and China. Within each country, the target cohort of pupils were those aged 9–10 and overall, 19 teachers, 10 from England and nine from China, participated in the study together with their pupils (n = 562). Two internationally validated instruments were used to collect the data and teacher behaviours were also measured systematically. In addition, structured observation was undertaken in classrooms in both countries. The results show that, on average, Chinese teachers scored higher on effective teaching measures and Chinese pupils outscored their English peers in the tests that were part of the study. This research project is currently collecting qualitative data but its findings, to date, reinforce the findings from previous research studies suggesting that certain teacher behaviours and classroom factors work effectively to improve student learning outcomes.