Physical inactivity and health

Gail Sheppard

Key points

• • Introduction
• • The rise of physical inactivity and sedentary behaviour
• • Physical inactivity, sedentary behaviour and health
• • Economic costs of physical inactivity and sedentary behaviour
• • Measuring physical inactivity, activity and sedentary behaviour
• • Current levels of physical inactivity and sedentary behaviour in the UK
• • UK physical activity guidelines
• • Benefits of increasing physical activity and reducing sedentary behaviour
• • Summary

Introduction

This chapter explains how inactivity and sedentary behaviour have risen over time, and why they are collectively an important public health priority. The chapter discusses how they contribute to non-communicable diseases, early death and costs to the economy. It will describe how inactivity and sedentary behaviour are measured and how recent surveys, such as UK travel surveys, show that the population is moving less and less. The chapter outlines the UK guidelines for activity and reducing sedentary behaviour, and concludes with an overview of the evidence that shows how physical activity protects against disease and early death, and promotes good health. It is important to set out what we mean by inactivity and sedentary behaviour.

• • Inactivity means not doing enough physical activity; a person is not meeting the amount of physical activity that is recommended for good health
• • Sedentary behaviour means sitting, lying or reclining whilst awake
• (Tremblay et al., 2017)

Sometimes ‘physical inactivity’ is used as an umbrella term for both, and sometimes researchers use the term ‘physical inactivity’ or ‘sedentary behaviour’ very deliberately.

The rise of physical inactivity and sedentary behaviour

Since the Stone Age, over two million years ago, there has been a significant shift away from humans surviving by being physically active hunter-gatherers. Over time,

Figure 7.1 From movement for survival to an inactive lifestyle Source: Uncle Leo/Shutterstock.com

improvements in agriculture and technology have led to people becoming increasingly inactive and more sedentary. This is known as the physical activity transition (Katzmarzyk and Mason, 2009).

Levels of physical inactivity have steadily increased over the past century. International research shows people’s work-related inactivity has risen since the 1970s, and between 2001 and 2016 inactivity in high-income countries rose from a prevalence of 31.6% to 36.8% (Knuth and Hallal, 2009; Guthold et al., 2018). This is twice as much inactivity as we see in low-income countries. We have also seen a shift towards more sedentary behaviours, such as sitting to travel, work and play. Some argue,

In view of the prevalence, global reach, and health effect of physical inactivity, the issue should be appropriately described as pandemic, with far-reaching health, economic, environmental, and social consequences.

(Kohl et al., 2012 p.294)

Reasons for the rise in physical inactivity and sedentary behaviour

Katzmarzyk and Mason (2009) explain the world’s population has become increasingly dense, and by 2008, for the first time ever, more people lived in urban areas rather than rural ones. Traditional rural life comprises small-scale farming and the use of bicycles and walking; urban living means using machines, a transport system, an organised labour force and the development of a very different social and economic environment. It can be characterised as one where many people earn money from industry and service-based occupations, desk-based work is common, domestic activities are light and leisure time is spent watching television or interacting with a computer. In summary, inactivity has grown because ^[1]

Together these developments have decreased people’s everyday moderate activity, increased sedentary behaviour and made vigorous activity rarely necessary.

Over centuries humans have undergone a physical activity transition leading to a rise in physical inactivity and sedentary behaviour.

Physical inactivity, sedentary behaviour and health

Early studies into physical activity/inactivity and cardiovascular disease

In the mid-twentieth century, three seminal research studies introduced the idea that inactivity may be a cause of cardiovascular disease and activity may protect health. The London Transport Workers Study in the 1950s was one of the first contemporary research studies to suggest a connection between inactivity and cardiovascular disease. Professor Jeremy Morris and his colleagues studied those who worked on London buses and found that those who sat for most of the time, the bus drivers, had more heart attacks than the active bus conductors who climbed up and down the bus steps many times during the working day, even when both groups were matched for age (Morris et al., 1953).

The Harvard Alumni Study (Paffenbarger et al., 1978) researched 17,000 excollege students aged 35 to 74 years old. They found those who were less active had experienced more heart attacks than those who were more active. Men whose activity, comprising walking, stair climbing and strenuous sport, burnt less than 2,000 calories

Figure 7.2 A typical London bus in the 1950s Source: Delpixel/Shutterstock.com per week were 64% more likely to have a heart attack than those whose activity was greater. The Framingham Heart Study, a series of long-term multigenerational studies into the factors that contribute to cardiovascular disease, included research into physical activity and found more death from cardiovascular disease among inactive than active men and women (Kannel and Sorlie 1979).

Over the next 50 years, research in this field vastly increased (Lee et al., 2012). Researchers questioned whether the benefits to health were due to the presence of activity, and how much activity, or whether the harms to health were due to the presence of inactivity, and how much inactivity. From this emerged a new branch of work into the health impacts of time spent with almost no activity at all, sedentary behaviour.

• [1] urbanisation fuels and is fuelled by economic growth • mechanised labour-saving devices in the workplace and home have proliferated • built environments are conducive to motor vehicles and to perceptions that theenvironment is less safe for activities such as walking • the environment has led to changes in people’s norms and expectations, the general social climate