Harry Rossiter: Introduction

Exercise Bioenergetics in Health and Disease

Introduction
Our research focuses on the determinants of the ability to sustain muscular exercise in health and disease.

High exercise tolerance is a key determinant of health, quality of life and mortality. We are therefore interested in the effective integration of the multiple systems that control and limit energy production (termed bioenergetics) during exercise.

Oxygen transport, utilisation and exercise tolerance?
The ability to sustain muscular exercise is highly dependent on the ability to transport and utilise oxygen. As such, control or limitation of oxidative energy transfer can occur at many points within the integrated systems that contribute to transporting oxygen from the atmosphere to the where it is utilised in the exercising muscles. Our aim, therefore, is to better understand this integrated process in order to address the question: what determines exercise tolerance in health and disease?

Such a question poses challenging demands of human physiology, requiring perspectives from the smallest atoms hydrogen (whose component electron and proton both drive energy production and contribute to fatigue) to the complex systems interactions of brain, muscle, heart and lungs. Therefore, an integrative approach is necessary to better understand the determinants and limitations of human exercise performance. Exercise intolerance – being defined as the inability to sustain a particular work rate for a duration sufficient to complete the task – is not simply the domain of the elite athlete, but rather extends over a wide continuum of function to include, for example, the healthy elderly and patients with chronic diseases of the heart, lungs or muscles. Amelioration of intolerance, therefore, has important implications for the capability of independent living and the quality of life. To investigate these systems we use an integrated approach, including:

adapted from Wasserman et al (1999)

• In vivo structural imaging, modelling and assessment of oxygen delivery and utilisation in murine models
• Bioenergetics using magnetic-resonance & near-infrared spectorocopy and cardiopulmonary exercise testing
• Clinical applications in chronic heart disease and chronic obstructive pulmonary disease

Why are we interested in exercise tolerance?
“Exercise is not a mere variant of rest… it is the essence of the machine”
Joseph Barcroft (1872-1947)

The main driver for this question is the still poorly-understood dynamic between physical activity patterns, health and predisposition to chronic diseases such as diabetes, heart disease and pulmonary disease as highlighted by the World Health Organisation (“Health and Development Through Physical Activity and Sport”, 2003).

What is more poor exercise tolerance contributes to inactivity, which is known to be an “actual cause” of many chronic diseases (USA Centers for Disease Control). As such, the ability to sustain muscular exercise is a powerful predictor of mortality. By investigating the mechanisms to determine exercise intolerance we aim to improve health, activity and quality of life.