Owen Payne’s MSc Thesis Proposal

Title: “The effect of aerobic fitness on exercise-induced diaphragm fatigue in females”

Supervisor: Dr. Bill Sheel
Committee members: Dr. Jeremy Road, Dr. Donald Mackenzie

Abstract: Muscle fatigue can be described as the temporary loss of the force producing capacity of a muscle resulting from muscle activity under load. In healthy humans, diaphragm fatigue can occur during high-intensity dynamic exercise, such as cycling or running. Current evidence suggests that females are more resistant to exercise-induced diaphragm fatigue. While the mechanisms behind this resistance are not well understood it has been suggested that the female diaphragm relies more on aerobic metabolism and that females activate their accessory respiratory muscles to a greater extent than males. Additionally, aerobic fitness may play a role in diaphragm fatigue development. During high-intensity dynamic exercise highly-aerobically fit humans ventilate significantly more than healthy normal humans, but do not experience a significantly different incidence or magnitude of diaphragm fatigue. Currently, the effect of aerobic fitness on diaphragm fatigue has only been investigated in a cohort of almost entirely males. Since females appear to be more resistant to diaphragm fatigue, it may be possible that highly-aerobically fit females may experience an even lower incidence and magnitude of diaphragm fatigue than less aerobically fit females. The purpose of this thesis is to understand if aerobic fitness effects the development of exercise-induced diaphragm fatigue in females. It is hypothesized that highly-aerobically fit females will experience a lower incidence and magnitude of diaphragm fatigue.