Thesis (M.Phys.Ed.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 161-171. Also available online.

Thesis (M.S.)--Slippery Rock University, 2002. / Includes bibliographical references (leaves 59-63).

Thesis (M.S.)--Springfield College, 2004. / Includes bibliographical references.

Thesis (Psy. D.)--University of Indianapolis, [2005]. / Includes bibliographical references (leaves 41-46). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Psy. D.)--University of Indianapolis, [2005]. / Includes bibliographical references.

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Perception of effort, defined as “the conscious sensation of hard, heavy and strenuous exercise”, is known to regulate endurance performance and human behaviour. Perception of effort has recently been shown to be exacerbated by mental exertion and is also known to be a main feature of fatigue. However, to date, not only its neurophysiology but also how manipulations of perceived exertion might impact endurance performance remain poorly understood. The main aim of this thesis was to investigate how manipulations of perceived exertion might impact endurance performance. This thesis is divided in two parts: central and peripheral manipulations of perceived exertion. In each part, three experimental chapters aimed to get a better insight in the neurophysiology of perceived exertion and its impact on endurance performance. In the first part (central manipulations), we firstly investigated the impact of exacerbating perceived exertion via mental exertion involving the response inhibition process on self-paced running endurance performance. This study demonstrated that as with time to exhaustion tests, time trial performance is impaired following mental exertion leading to mental fatigue. Secondly, we investigated whether mental exertion leading to mental fatigue could alter the rate of central fatigue development during constant load whole-body exercise. This study demonstrated that the exacerbated perception of effort in presence of mental fatigue does not reflect an altered rate of central fatigue development, but is likely to be due to i) an impaired central motor command and/or ii) an alteration of the central processing of the corollary discharge. Thirdly, we investigated whether mental exertion could impact the repeatability of maximal voluntary contraction of the knee extensors. We found that contrary to submaximal exercise, force production capacity is not altered by mental exertion. Finally, these three studies demonstrated that i) mental exertion negatively impacts submaximal exercise but not maximal exercise and that ii) mental fatigue differs from central fatigue. In the second part (peripheral manipulation), we firstly developed and tested the reliability of a new endurance exercise model non-limited by the cardiorespiratory system (one leg dynamic exercise), which will be of benefits for future researches aiming to manipulate feedback from group III-IV muscle afferents. Secondly, we described neuromuscular alterations induced by this exercise and tested a new methodology to indirectly measure feedback from group III-IV muscle afferents. This study demonstrated that one leg dynamic exercise induced central and peripheral fatigue and also a decrease in spinal excitability associated with an increase in cortical excitability. Furthermore, this study also suggests that monitoring cardiovascular responses during muscle occlusion might be a suitable tool to indirectly measure feedback from group III-IV muscle afferents. Thirdly, we tested the corollary discharge and afferent feedback model of perceived exertion with electromyostimulation. This study demonstrated for the first time that for the same force output, perception of effort generation is independent of muscle afferents and reflects the magnitude of the central motor command (manipulated by electromyostimulation). All together, these findings provide further evidence in support of the corollary discharge model of perceived exertion, and provide a new exercise model to investigate and manipulate perception of effort. This thesis, when integrating both experimental parts, provides new insight on how perception of effort regulates endurance performance. Specifically, it demonstrates how muscle fatigue is a contributor of the continuous increase in perception of effort during endurance exercise, but also that other contributors play a role in this increase in perception of effort. Indeed, we demonstrated for the first time that i) perception of effort alterations in the presence of mental fatigue is independent of any alterations of the neuromuscular system, and ii) muscle afferents does not directly impact perception of effort, but may influence it indirectly via their role in motor control.

There is a general consensus among sport coaches and practitioners that it is better to work with a cohesive team. Research on cohesion has provided positive links between cohesion and performance as well as the overall well-being of the team and its members. The purpose of this study is to develop and evaluate a cohesion-building programme under an Action Research paradigm. The Group Environment Questionnaire, in parallel with focus group discussions were used to assist in the development and evaluation of a cohesion-building programme tailored to the specific needs of the Rhodes University men’s basketball 1st team. The team is known to be a good team but it was missing something that made it become great. Fostering higher cohesiveness was deemed to be the missing link to the chain of success. Various changes were brought to the 1) team structure, 2) team processes, 3) team environment to enhance the team’s cohesiveness levels. It was found that the programme was positive and powerful in that it accelerated the process of cohesion building within the team. It was also found that the programme had the power to transcend demographical barriers and unite people from diverse backgrounds. Finally, the programme increased the team’s performance level and enabled it to achieve objectives that were never achieved by any other men’s basketball team at Rhodes University before. Naturally there are going to be some ups and downs, especially if you have individuals trying to achieve at a high level. But when we stepped in between the lines, we knew what we were capable of doing. When a pressure situation presented itself, we were plugged into one another like a cohesive unit. That’s why we were able to come back so often and win so many close games. And that’s why we were able to beat more talented team. - Michael Jordan (former Chicago Bulls; NBA Hall of Famer).

This thesis summarises a series of academic publications that make a contribution to the field of sports nutrition over a period of 30 years. It begins with research in the field of carbohydrate and endurance sport reflecting the early era of research into carbohydrate and endurance performance, and evolves into studies investigating the impact of sports nutrition and hydration on team sports. It presents papers and other peer reviewed outputs that focus on the application of scientific knowledge to enhance human performance, whilst demonstrating the increasing awareness of the relative importance of carbohydrate and hydration in a range of both female and male team and individual sports. The thesis also highlights the challenge faced by the manufacturers of sports nutrition products in making use of advances in science to develop new and innovative products. The thematic nature of this thesis shows how sports nutrition continues to evolve. As science identifies new and legal means of enhancing human performance, so sport, athletes and coaches will demand more advanced and specialised approaches to refuelling and hydration. This thesis draws together findings from a series of publications which demonstrate how scientists, coaches, athletes and sports nutrition manufacturers need to work closely together to research, identify and interpret the next stages in an exciting and demanding area of research. It also reflects the scientific advancement in the field of sports nutrition over a thirty year period, identifies possible areas for future research, and the continued application of hydration and nutrition strategies to enhance male and female endurance and team sports.

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