Skeletal muscle and gait analysis in chronic heart failure: new insights into impaired exercise capacity

[Truncated] Chronic heart failure (CHF) is amongst the most profound health burdens in Australia and worldwide. It is characterized by severe disability that impacts tasks of daily living and is associated with extreme fatigue. Indeed, CHF is one of the most common reasons for hospital admission and general practitioner consultations in the elderly and it is estimated that CHF accounts for >$1 Billion in annual health care costs in Australia ($34 Billion annually in the USA). Low exercise capacity is a strong independent predictor of prognosis in CHF and used clinically to stratify patients for transplantation and ventricular assist device implantation. However, development of optimal exercise-based treatment to improve functional capacity in CHF is hampered by a lack of understanding of the fundamental mechanisms underpinning exercise intolerance. In many cases, the cardiac function is not directly associated with exercise capacity in CHF and growing evidence points to an important role for skeletal muscle in dictating disease severity and the progression. The majority of studies focusing on skeletal muscle in CHF have either addressed gross physiological function (e.g. muscle mass in relation to exercise capacity) or skeletal muscle histopathology. Surprisingly, few studies of CHF have examined in vivo muscle-level morphology and functional properties and their impact on locomotor biomechanics, despite the known association between these variables in other populations. Therefore, the general aims of the present thesis were: 1) to study in vivo morphological and mechanical properties of skeletal muscle in CHF patients and 2) to investigate how these properties impact on exercise and functional walking capacity. The ultimate goal was to enhance the evidence base for rehabilitation of individuals with CHF.