Using Optoelectronic Plethysmography to Objectively Characterise and Manage Breathing Patterns in Athletes With and Without Respiratory Disorders

Optoelectronic plethysmography (OEP) is a non-invasive 3D motion capture-based system that tracks chest wall movement. The purpose of this thesis was to characterise the breathing patterns of athletes with and without respiratory disorders, namely exercise-induced bronchoconstriction and dysfunctional breathing, at rest and during exercise. OEP breath volumes agreed well with breath-by-breath gas analysis in support of previous findings. Normative ranges for OEP-derived breathing pattern parameters for a non-pathological population at rest and during exercise were presented, with candidate timing and phase angle parameters differing between rest and exercise identified (Chapter 4). It was subsequently found that phase angle breathing parameters significantly differed between a healthy population group at rest and athletes with exercise-induced bronchoconstriction (EIB) during bronchoconstriction (Chapter 5). Following this, significant differences in regional contribution and phase angle breathing parameters were found between athletes with and without dysfunctional breathing at rest and during exercise (Chapter 6).

A novel real-time OEP feedback system was developed and used as part of an acute breathing retraining intervention for athletes with dysfunctional breathing (Chapter 7). Significant reductions in phase angles values of RcAbPhase (ribcage versus abdomen), RCpAbPhase (upper ribcage versus lower ribcage and abdomen), and AbSPhase (abdomen versus shoulders) were found post-intervention indicating real-time OEP feedback may be a useful breathing retraining tool during high intensity exercise.

Although OEP has been shown to be a powerful breathing pattern measurement tool, it is not without its limitations. Therefore, potential portable alternatives to OEP were explored including an inspiratory muscle training device (Chapter 8) and an impedance pneumography (IP) system (Chapter 9). Both systems displayed some promise by correlating with the respiratory rate obtained from the OEP system at rest (r > 0.8; ICC > 0.9). For the IP, the agreement was reduced during exercise (r > 0.4; ICC > 0.5). Overall, OEP was shown to potentially be a powerful tool for diagnosing and management of respiratory disorders in athletes.