BURA Collection:

Supraspinal fatigue after normoxic and hypoxic exercise in humans

2013-02-27T11:07:18Z

Title: Supraspinal fatigue after normoxic and hypoxic exercise in humans Authors: Goodall, S; Gonzalez-Alonso, J; Ali, L; Ross, EZ; Romer, LM Abstract: Inadequate cerebral O₂ availability has been proposed to be an important contributing factor to the development of central fatigue during strenuous exercise. Here we tested the hypothesis that supraspinal processes of fatigue would be increased after locomotor exercise in acute hypoxia compared to normoxia, and that such change would be related to reductions in cerebral O₂ delivery and tissue oxygenation. Nine endurance-trained cyclists completed three constant-load cycling exercise trials at ∼80% of maximal work rate: (1) to the limit of tolerance in acute hypoxia; (2) for the same duration but in normoxia (control); and (3) to the limit of tolerance in normoxia. Throughout each trial, prefrontal cortex tissue oxygenation and middle cerebral artery blood velocity (MCAV) were assessed using near-infrared spectroscopy and trans-cranial Doppler sonography, respectively. Cerebral O₂ delivery was calculated as the product of arterial O₂ content and MCAV. Before and immediately after each trial, twitch responses to supramaximal femoral nerve stimulation and transcranial magnetic stimulation were obtained to assess neuromuscular and cortical function, respectively. Exercise time was reduced by 54%in hypoxia compared to normoxia (3.6 ± 1.3 vs. 8.1 ± 2.9 min; P<0.001). Cerebral O₂ delivery,cerebral oxygenation and maximum O₂ uptake were reduced whereas muscle electromyographic activity was increased in hypoxia compared to control (P <0.05).Maximum voluntary force and potentiated quadriceps twitch force were decreased below baseline after exercise in each trial;the decreases were greater in hypoxia compared to control (P<0.001), but were not different in the exhaustive trials (P>0.05). Cortical voluntary activation was also decreased after exercise in all trials, but the decline in hypoxia (Δ18%) was greater than in the normoxic trials (Δ5-9%)(P <0.05). The reductions in cortical voluntary activation were paralleled by reductions in cerebral O₂ delivery. The results suggest that curtailment of exercise performance in acute severe hypoxia is due, in part, to failure of drive from the motor cortex, possibly as a consequence of diminished O₂ availability in the brain. Description: Copyright @ 2012 The Authors. This article can be accessed from the links below.

Organisational culture and coach-athlete relationships: An ethnographic study of an elite rowing club

2013-02-01T11:52:35Z

Title: Organisational culture and coach-athlete relationships: An ethnographic study of an elite rowing club Authors: Maitland, Alison Abstract: This thesis explores how coach-athlete relationships are influenced within the organisational culture of a rowing club. Relational Cultural Theory and the work of Weber are used to examine how the concept of organisational culture informs understanding of coach and athlete relating. The study, covering a complete competitive season, involved an eleven month long ethnography of an elite rowing club in Great Britain. The findings demonstrate the visceral, enculturated and complex nature of coach-athlete relationships in elite sport. Relational disconnection occurred in the disenchanted organisational life, where intrinsic values were subordinated to a rational quest for efficiency, control and ultimately success, as well as traditional social ordering based on status and gender. Relationships were characterised by power over relating, distance and impersonal relations, caretaking rather than caring about, fragile trust by the athlete and trust through surveillance by the coach, where emotion was concealed and conflict avoided. However, enacting shared identities, the emotion involved in competing and the fact this was a voluntary organisation with competing values, provided an escape from simulacra of elite sport to allow for multi-value paradigm of interests. The opportunity for coaches and athletes to connect with each other based on their values and with emotion exposed their humanity and revealed the potential for relational mutuality and authenticity. The study challenges the valorised coaching and elite sport relationships and lifestyle. Implications for coaching include providing individuals with confidence to raise the issue of relationship, providing coaches and athletes with knowledge of connection and disconnection in relationship and the outcome on well-being. The need to develop a systemised approach to embedding growth-fostering relationships in the culture of high performance sport is highlighted. Description: This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.

Sport, children's rights and violence prevention: A source book on global issues and local programmes

2012-12-19T13:23:46Z

Title: Sport, children's rights and violence prevention: A source book on global issues and local programmes Authors: Brackenridge, CH; Kay, T; Rhind, D Editors: Brackenridge, CH; Kay, T; Rhind, DJA Abstract: In line with the Convention on the Rights of the Child (CRC), UNICEF has been a strong advocate of children’s right to leisure and play. It recognizes the intrinsic value sports have in promoting the child’s health and well-being, education and development, and social inclusion, including by fostering the culture of tolerance and peace. Every child has the right to play safely, in an enabling and protective environment. However, although under-researched, evidence shows that children have been subjected to various forms of violence, abuse and exploitation ranging from undue pressure to achieve high performance, beatings and physical punishment, sexual harassment and assaults, to child labour and trafficking. The violence that children experience can lead to lifelong consequences for their health and development. It can also have devastating consequences. Article 19 of the CRC asserts that all children have the right to be protected from violence, calling on State Parties to take all appropriate measures for the protection of children, including while in the care others. Measures include strengthening child protection systems; increasing awareness and strengthening the protective role of parents, teachers, coaches and others caregivers as well as the media; developing and implementing standards for the protection and well-being of children in sports; implementing sport for development and other international programmes and initiatives; and improving data collection and research to develop an evidence-base of “what works”. Above all, the protection of young athletes starts by ensuring that those around children regard them in a way that is appropriate to their needs and that is respectful of their rights - as children first and athletes second. This book provides an expanded set of evidence and resources to back up the 2010 report from the UNICEF Innocenti Research Centre in Florence, Italy - Protecting Children from Violence in Sport: A review with a focus on industrialized countries. I am delighted to provide a Foreword as it complements the ongoing work being done by UNICEF in development and humanitarian environments to make sport a safer place for children. Description: Copyright @ Brunel University, 2012

Effects of run-up velocity on performance, kinematics, and energy exchanges in the pole vault

2012-12-10T12:51:38Z

Title: Effects of run-up velocity on performance, kinematics, and energy exchanges in the pole vault Authors: Linthorne, NP; Weetman, AHG Abstract: This study examined the effect of run-up velocity on the peak height achieved by the athlete in the pole vault and on the corresponding changes in the athlete's kinematics and energy exchanges. Seventeen jumps by an experienced male pole vaulter were video recorded in the sagittal plane and a wide range of run-up velocities (4.5-8.5 m/s) was obtained by setting the length of the athlete's run-up (2-16 steps). A selection of performance variables, kinematic variables, energy variables, and pole variables were calculated from the digitized video data. We found that the athlete's peak height increased linearly at a rate of 0.54 m per 1 m/s increase in run-up velocity and this increase was achieved through a combination of a greater grip height and a greater push height. At the athlete's competition run-up velocity (8.4 m/s) about one third of the rate of increase in peak height arose from an increase in grip height and about two thirds arose from an increase in push height. Across the range of run-up velocities examined here the athlete always performed the basic actions of running, planting, jumping, and inverting on the pole. However, he made minor systematic changes to his jumping kinematics, vaulting kinematics, and selection of pole characteristics as the run-up velocity increased. The increase in run-up velocity and changes in the athlete's vaulting kinematics resulted in substantial changes to the magnitudes of the energy exchanges during the vault. A faster run-up produced a greater loss of energy during the take-off, but this loss was not sufficient to negate the increase in run-up velocity and the increase in work done by the athlete during the pole support phase. The athlete therefore always had a net energy gain during the vault. However, the magnitude of this gain decreased slightly as run-up velocity increased. Description: Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.