Whilst many countries have guidelines recommending the minimum amount of physical activity a person should take to stay healthy, much of this advice is conflicting, making it difficult for healthcare professionals to assess whether a person is getting enough exercise.

Scientists at the School for Health at the University of Bath, working with co-investigator Dr Alan Batterham from the University of Teesside, found that around nine out of every ten men they studied could be categorised as active or sedentary, depending on which guidelines were followed.

Dr Dylan Thompson, senior lecturer at Bath, explained: "Recommended levels of physical activity are supposed to give the public and health providers a guideline of the minimum amount of activity needed for good health, but these messages seem to vary a lot.

"For example, in the UK, the recommendation is that adults should do at least 30 minutes of moderate physical activity per day in periods of 10 minutes or more, five times a week.

"In the US, some guidelines recommend an overall volume of activity, recommending an average of 60 minutes of moderate intensity activity per day, but this includes any activity you might do - even if it lasts less than ten minutes.

"So, if you did a couple of two-hour walks at the weekend, and just a little bit of activity during the week, these US guidelines would define you as sufficiently active but according to the UK guidelines from the Department of Health you would be told that you needed to do more.

"Being physically inactive is a major risk factor for heart disease just like high blood pressure and high cholesterol, so it's really important that healthcare professionals are able to identify which people should be getting more physical activity so they can give them appropriate advice and support.

"If you went to the doctor to get your blood pressure or cholesterol checked, you'd expect to get a consistent result each time - we're saying that assessments of physical activity need to be just as stringent."

The researchers, who published their study in the online open access journal PLoS ONE, hope it will lead to a more consistent approach to gauging physical activity.

Dr Alan Batterham, a researcher in the Health and Social Care Institute at Teesside, remarked: "Deciding on whether people are sufficiently active or not depends on where you set the bar. We found that subtle differences in the definition of the minimum amount of physical activity required for health make a big difference to the proportion of people categorised as active or inactive."

Dr Thompson added: "In the long term, we need better evidence about precisely how much physical activity is needed for health, and we need to offer people consistent advice about their physical activity options.

"At the moment, we seem to have a very prescriptive 'one size fits all' approach but the 'size' varies enormously between guidelines. This confusion and inconsistency may be preventing people from taking the message on board that being active can make a huge difference to your health."

Source: University of Bath