The World Health Organization (WHO) recently published a report that found a quarter of the world's adults do not get enough exercise, putting themselves at risk of developing or exacerbating diseases linked to inactivity. The study, published in The Lancet Global Health journal, found wealthy countries in particular were lacking in exercise and women were more sedentary throughout the world.
We spoke to John Cairney, a professor at the University of Toronto's Faculty of Kinesiology and Physical Education, about why so little progress has been made in reducing levels of inactivity worldwide and what can be done to reverse this trend.
Why haven't there been more improvements in the levels of activity among men and women globally?
It is complicated, but one issue that is frequently discussed concerns the fundamental lifestyle changes that have occurred since the 1800s. Quite simply, technology. The automobile, the computer, the TV ... Everyday labour saving devices, coupled with fundamental changes in work - the transition from farming to manual labour, the increase in sedentary occupation like office based work - have all led to less daily energy expenditure. We have transformed ourselves in a relatively short period of time evolutionary speaking, from hunter-gatherers, where movement was essential for life, to a largely sedentary existence that is now causing significant negative effects on mortality and health more generally. We now have to be intentional about incorporating movement into our daily lives. That takes effort and can feel like work.
Were you surprised to learn that that high-income countries were among the least active and that women were more sedentary throughout the world?
Not really surprised. It is in exactly those countries where these shifts in lifestyles have been the most profound. I want to be careful here however as the challneges that many low income countries confront - famine, war, extreme poverty - are the major determinants of mortality. Physical inactivity is much less of a priority.
With regard to gender, we have known for some time that rates of physical activity decline faster for females and this begins in adolescence, establishing a trend that persists throughout the life course.
Why is that?
Our research has shown, for example, that girls report on average lower levels of perceived competence with regard to athletic ability relative to boys, which leads to lower physical activity. Changes with puberty also have been implicated, feeling self-conscious about their bodies, not wanting to get sweaty, etc.
People who did less than 150 minutes of moderate exercise - or 75 minutes at a vigorous intensity - a week were classified as inactive by the report. Does that seem a bit harsh to you? I thought any amount of exercise was better than none?
We do have data to suggest that among sedentary individuals even modest increases in activity confer health benefits. But, more time spent in activities that are moderate or vigorous confers even greater benefits. Unlike, say, consumption of alcohol where we stress the importance of moderation, in the case of physical activity, more truly is better.
Why is inactivity such a health risk?
Physical activity leads to many positive physiological and psychological adaptations in the body that are beneficial to health. It is this pervasive impact that helps to explain why it is associated with prevention of so many different chronic diseases.
What can be done to help more people be more active?
Awareness of the importance of physical activity, through studies and reports like this are only part of the answer. In our faculty, researchers are invested in finding the social, biological and psychological determinants of physical activity to create interventions that increase physical activity in the population. Personally, I think it is critical that we start in early childhood, where most children love to move already. The challenge is to prevent physical activity declines before they occur. We must look at the structure of our environments - do they promote or deter movement? - and ensure children have the physical literacy - the competence, confidence and enjoyment - to be physically active for life.