Introduction

There is an extensive scientific literature dating back several decades linking lack of physical exercise with depressed mood, limited coping skills and low levels of psychological well-being [1, 2]. Physical inactivity is also associated with increased risk for many of the medical problems discussed in this book. In some illnesses, such as coronary heart disease (CHD), physical inactivity is thought to have a causal role in disease risk, mediated through metabolic and other pathways [3]. In other conditions, such as chronic pain, inactivity does not cause the problem but nevertheless it contributes to disability. Physical exercise is also important in the regulation and management of chronic conditions, such as diabetes. The question therefore arises of whether the associations between depression and medical problems are mediated through low levels of physical activity and increased sedentary behaviour. Such possibilities have important implications for prevention and patient care.

This chapter discusses the evidence linking physical activity, depression and medical problems and addresses two general questions: First, is reduced physical activity responsible in part for associations between depression and the medical conditions and disabilities discussed in this book? Second, can increases in physical exercise improve the mood of patients and, therefore, be used in the management of these medical problems? The chapter begins with a discussion of the associations between physical activity, depression and depressed mood in clinical and population studies.