Nature’s cure in the modern age

OliverMyttonDr Oliver Mytton , an Honorary Specialist Registrar in public health and PhD student writes about his research at CEDAR.

We’ve been doing it since we lived in caves. Over two thousand years ago, Hippocrates said it was good for our health. Today we know it can help prevent or treat many common chronic conditions: heart disease, stroke, diabetes, some cancers, dementia, depression, arthritis and some lung diseases. Its potential to improve people’s health is vast. If it were a drug, wouldn’t you take it?

But it is not a drug. It is physical activity.

Our modern scientific understanding of the importance of physical activity began with a very elegant study by the epidemiologist Jerry Morris of London bus-workers in the 1950s. The study followed bus drivers and conductors for several years, finding a much higher rate of heart disease among the relatively sedentary drivers compared to their active colleagues, the conductors, who spent their working days walking the stairs of the bus. This study was particularly compelling because the drivers and conductors were similar in most respects so the differences in heart disease could be ascribed to their differing physical activity. And whilst these findings might seem intuitive today, they were greeted with some scepticism when they were first published in 1953.

Since then, science has revealed much more about how physical activity affects health. In response, our government and health services have tried to get people more active through a combination of education and persuasion. However, British adults are no more active today than we were in the 1950s. Indeed, because of changes in how people travel and work, activity levels today are lower. The last 60 years has been a period of tremendous medical advance, but science is still trying to satisfactorily answer the question of how to get more people more active.

My research with the Physical Activity and Public Health group is focused on the ‘how’. To date, initiatives have tended to focus on recreational activity, for example much hope has been placed in the ‘Olympic legacy’. They tend to centre on the individual, for example ‘exercise on prescription’, where GPs recommend exercise to patients with an identified medical problem. Our research takes a different approach: we study walking and cycling, not as recreational activities, but as everyday activities to get from A to B. We also focus not on the individual, but instead on the built environment in which people live.

Indeed, a growing number of advocates argue that changing the environment to make walking and cycling the preferred choice (e.g. pedestrian areas, traffic calming or cycle paths) may be a more effective way to promote widespread and sustained increases in physical activity than what we have tried in the past. They point to the Netherlands, with its much higher levels of cycling than the UK and a vastly different infrastructure to support this. Others are equally confident that changes along these lines would not improve health, and risk wasting public money. This is an area rich in opinion and poor in evidence. There is a need for science to provide objective evidence about whether changes to the environment actually can influence people’s physical activity and wellbeing.

Our research seeks to provide this evidence. In many areas of medical research, the standard approach is the controlled trial, where researchers allocate individuals randomly to two groups. One group is given the new treatment and the second is not. In my research, however, we cannot randomly give people new environments!

Instead, my research group takes advantages of major changes to the environment that might affect physical activity. We call these ‘natural experimental studies’. Such studies are tricky to conduct. As with Jerry Morris’ bus-workers study, we need to find two groups which are sufficiently similar that we can reliably attribute any differences in physical activity to changes in the environment.

Using this approach, my research will not only look to understand if the environment affects physical activity, it will also look at how and how much. The size of the effect, and how it compares to other health initiatives, is particularly important for a government prioritising efforts to increase physical activity.

Of course it is unlikely that government would spend its health budgets on new infrastructure to promote walking and cycling, but my research can influence how cities grow and evolve. For example my findings can help town planners to consider health explicitly alongside other factors (carbon emissions, congestion, job creation) when assessing different options.

In the past, people sometimes have tried to build ‘healthy’ towns, but that’s not always what they ended up creating. Garden cities incorporated wide open spaces because received wisdom held that this improved people’s wellbeing. However emerging research suggests the consequent ‘urban sprawl’ promoted car use over walking and cycling, is likely to have undermined health. Good intentions then are not enough, governments also need robust evidence.

As Britain began rebuilding after World War II, Churchill said, “We shape our buildings, and thereafter they shape us”. On one level my work is about understanding how to increase physical activity, but on another level it is about what kind of world we live and work in.

And Jerry Morris? He practised what he preached, and lived until 99.