Want to cut the risk of cardiovascular disease? Walk faster, say University of Cambridge and University of Leicester researchers

Is it better to exercise for longer, or more intensely?

Researchers at the University of Cambridge and University of Leicester set out to discover the answer in a study in which 88,000 people wore wearable devices to help measure their activity levels.

Current guidelines from UK chief medical officers recommend that adults should be active every day and undertake 150 minutes of moderate intensity activity - such as a brisk walk - or 75 minutes of vigorous intensity activity - such as running - every week.

But it has not been clear if the overall physical activity volume - that is, the intensity of activity multiplied by time - is what is most important for health, or whether there is additional benefit from engaging in more vigorous activity.

The researchers analysed data from a research-grade activity tracker worn by 88,412 middle-aged adults free from cardiovascular disease in Great Britain on their dominant wrist for a week in the UK Biobank study.

They then explored the number of cardiovascular events, including ischaemic heart disease or cerebrovascular disease, in the study participants over an average follow-up period of 6.8 years.

They found increasing physical activity of any intensity is beneficial for health, but there was a greater reduction in the risk of cardiovascular disease when more of that activity was of at least moderate intensity.

Dr Paddy Dempsey, research fellow at the University of Leicester and MRC Epidemiology Unit at the University of Cambridge, and first author on the paper in the European Heart Journal, said: “Most large-scale studies to date have used questionnaires to determine participants’ physical activity levels, but physical activity intensity and duration is hard to recall accurately, especially when it comes to low intensity every day activities like washing the car, or sorting laundry.

“Without accurate records of physical activity duration and intensity it hasn’t been possible to sort out the contribution of more vigorous physical activity from that of overall physical activity volume.

“Wearable devices helped us to accurately detect and record the intensity and duration of movement for 90,000 individual UK Biobank participants, and we recently published an analysis of wearable device data demonstrating that moderate and vigorous intensity activity gives a greater reduction in the overall risk of early death.

“More vigorous physical activity may also reduce the risk of cardiovascular disease, over and above the benefit seen from the total amount of physical activity, as it stimulates the body to adapt to the higher effort required. This is what we set out to investigate in the research published today.”

The movement data collected enabled the team to calculate the total volume of activity and they worked out the percentage achieved through moderate and vigorous intensity activity.

Cardiovascular disease rates were 14 per cent lower when moderate-to-vigorous physical activity accounted for 20 per cent rather than 10 per cent of overall physical activity, even in those that otherwise had low levels of activity.

This was equivalent to converting a daily 14-minute stroll into a brisk seven-minute walk.

The lowest cardiovascular disease rates overall were observed among participants who undertook higher overall levels of physical activity and a higher proportion of moderate-to-vigorous physical activity.

But the researchers found that when the overall volume of physical activity increased, but the proportion from moderate-to-vigorous activity remained the same, there was little change in cardiovascular disease rates.

For example, doubling overall physical activity levels had no significant effect on cardiovascular disease rates if the proportion of that activity at moderate to vigorous levels remained at 10 per cent..

However, cardiovascular disease rates dropped by 23 per cent and 40 per cent when the proportion from moderate-to-vigorous physical activity rose by 20 per cent and 40 per cent respectively.

Pror Tom Yates, professor of physical activity, sedentary behaviour and health at the University of Leicester, and a senior author on the paper, said: “Our analysis of data from UK Biobank confirms that increasing the total amount of physical activity can lower the risk of suffering a heart attack or stroke, but we also found that achieving the same overall amount of physical activity through higher intensity activity has a substantial additional benefit.

“Our findings support simple behaviour-change messages that ‘every move counts’ to encourage people to increase their overall physical activity, and if possible to do so by incorporating more moderately intense activities.

“This could be as simple as converting a leisurely stroll into a brisk walk, but a variety of approaches should encourage and help individuals to find whatever is most practical or enjoyable for them.”

This study was supported by the National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre, the MRC Epidemiology Unit, UK Biobank, and NIHR Applied Research Collaborations East Midlands.