Using the interaction of speed and acceleration to detect repeated-sprint activity in team sports

ABSTRACT

Purpose

To compare the occurrence and characteristics of repeated-sprint (RS) activity in elite team sport competition when classified according to speed and/or acceleration, and their interaction via metabolic power (P_met). Methods: Elite male hockey players (N = 16) wore player-tracking devices in six international matches. Sprint efforts were defined using four separate classifications: speed >5.5 m?s^?1, acceleration >1.5 m?s^?2, speed-or-acceleration, and P_met >25.5 W?kg^?1. RS bouts were defined as ≥3 efforts with mean recovery ≤21 s. For P_met, RS bouts were also classified using a maximal recovery period ≤21 s. The number of sprint efforts and RS bouts, and the number of efforts, effort durations and recovery periods within RS bouts, were compared across each classification method, and between mean and maximal recovery criteria. Results: More RS bouts were identified via P_met (8.5 ± 2.8) than either speed and/or acceleration, and comprised more efforts (4.0 ± 0.4) with shorter recovery periods (11.5 ± 1.8 s). Fewer RS bouts (7.3 ± 2.8 vs. 8.5 ± 2.8) were identified with a maximum rather than mean recovery criterion. Conclusions: Definitions of sprint efforts and recovery periods which reflect ATP depletion and replenishment via P_met suggest that RS activity occurs frequently in team sport competition, and is more demanding than when speed and/or acceleration are used to define RS activity in variable-speed locomotion.     

Lactate accumulation following isometric exercise training and its relationship with reduced resting blood pressure

The purpose of this study was (a) to assess lactate accumulation during isometric exercise, and to quantify the shifts in accumulation following isometric training; and (b) to relate any training-induced changes in lactate accumulation to reductions in resting blood pressure. Eleven male participants undertook isometric training for a 4-week period using bilateral-leg exercise. Training caused reductions in systolic, diastolic, and mean arterial resting blood pressure (of -4.9 ± 6.3 mmHg, P = 0.01; -2.6 ± 3.0 mmHg, P = 0.01; and -2.6 ± 2.3 mmHg, P = 0.001 respectively; mean ± s). These were accompanied by changes in muscle activity, taken as electromyographic activity to reach a given lactate concentration (from 114 ± 22 to 131 ± 27 mV and from 136 ± 25 to 155 ± 34 mV for 3 and 4 mmol · L(-1) respectively. Training intensity expressed relative to peak lactate was correlated with reduced resting systolic and mean arterial blood pressure. Training caused significant shifts in lactate accumulation, and reductions in resting blood pressure are strongly related to training intensity, when expressed relative to pre-training peak lactate. This suggests that higher levels of local muscle anaerobiosis may promote the training-induced reductions in resting blood pressure.     

The production of Australian professional development policy texts as a site of contest: The case of the federal quality teacher programme

This paper reveals how the provision of teacher professional development is conceptualised within the Australian Government Quality Teacher Programme (AGQTP) policy text and its predecessors, and uses these texts to infer the nature of the production practices associated with the development of these policies. The paper argues that multiple tensions within these texts gesture towards support for complex and contested approaches to professional development during the policy production process. To make sense of this contestation, the paper draws suggestively upon Bourdieu’s field theory, which conceptualises the social world as consisting of social spaces or “fields”, and extensions of his theory, which reveal fields as exerting considerable influence upon one another. The paper argues that “Quality Teacher Programme” texts infer support for more progressive, social democratic approaches to the provision of teacher professional development within the educational policy field, as well as more economistic and neoliberal approaches.     

Towards a meta-research agenda in science and enviormental educaion

Abstract

This paper begins by establishing the existence of a debate in the broader educational community about the nature, meaning and significance of educational research, and its recognition that different approaches to educational research do not simply represent different strategies for data collection but rest on and express different ideologies that implicate different political attitudes among teachers, students, subject‐matters,schools, support agencies and researchers themselves. Evidence can be seen that this debate is beginning to appear in the science education literature and it is believed that the arguments can be extended.

It is argued that research in science education and environmental education needs to consider methodology in the political terms of ideology, rather than simply in the technical terms of method and technique. Some of the recent thinking about the politics of method in both science education and environmental education, is then considered briefly and a number of meta‐research questions are proffered that might focus further attention on the political theory of research in these two fields.