Image copyright Thinkstock Image caption Many busy, working people try to fit in all their exercise at the weekend

Cramming all your recommended weekly exercise into one or two weekend sessions is enough to produce important health benefits, a study suggests.

And being active without managing 150 minutes of moderate activity a week was still enough to reduce the risk of an early death by a third.

The findings are based on a survey of about 64,000 adults aged over 40 in England and Scotland.

Health experts said purposeful exercise was key to better health.

Researchers from Loughborough University and the University of Sydney analysed data on the time people spent doing exercise and their health over 18 years.

They found that no matter how often people exercised in a week or for how long, the health benefits were similar as long as they met the activity guidelines.

Fighting the flab

This was good news for people with a busy lifestyle who turned into "weekend warriors" in order to fit in all their recommended physical activity, they said.

Compared with those who didn't exercise at all, people who did some kind of physical activity - whether regularly or irregularly - showed a lower risk of dying from cancer and from cardiovascular disease (CVD), which can lead to heart attacks and strokes.

"Weekend warriors", who did all their exercise on one or two days of the week, were found to lower their risk of dying from CVD by 41% and cancer by 18%, compared with the inactive.

Those who exercised regularly on three or more days per week reduced their risks by 41% and 21%.

Even the "insufficiently active" lowered their risk by a significant amount - 37% and 14%, the researchers said, writing in an article published online in JAMA Internal Medicine.

Image copyright Thinkstock Image caption "Weekend warriors" are more likely to be men than women

How much physical activity should I do?

People aged 19-64 should try to do:

at least 150 minutes of moderate aerobic activity, such as cycling or fast walking every week, and

strength exercises (such as lifting weights) on two or more days a week that work all the major muscles

Or

75 minutes of vigorous aerobic activity, such as running or a game of singles tennis every week, and

strength exercises on two or more days a week that work all the major muscles

Or

a mix of moderate and vigorous aerobic activity every week, such as two 30-minute runs plus 30 minutes of fast walking, and

strength exercises on two or more days a week that work all the major muscles

Source: NHS Choices and Public Health England

What do you think? Join the debate on the BBC Lifestyle & Health Facebook page.

Dr Gary O'Donovan, study author and expert in physical activity and health, from Loughborough University, said the key was doing exercise that was "purposeful, and done with the intention of improving health".

"You are not going to fidget or stand your way to health," he said.

He added that a commitment to an active lifestyle was usually accompanied by other healthy lifestyle options, which made a positive difference regardless of body mass index (BMI).

But Dr O'Donovan said no-one yet knew the best way of meeting the weekly recommended exercise total.

'Every little counts'

The study cannot show a direct link between physical activity and a reduction in health risks in individuals.

But extensive research has shown that exercise and a healthy diet can reduce the risk of a range of diseases - such as cancer, heart disease and type-2 diabetes - as well as helping to control weight, blood pressure and reduce symptoms of depression.

Justin Varney, national lead for adult health and wellbeing at Public Health England (PHE), said: "The maximum health benefits are achieved from 150 minutes of moderate activity per week.

"However, every little counts and just 10 minutes of physical activity will provide health benefits."

PHE's How Are You quiz gives you a health score and links to free local information, apps and tools to improve that score.