Study pinpoints the length of incidental activity linked to health benefits

"From walking up the stairs to speedily mopping the floors; in recent years we've come to understand that it is not just structured exercise that is good for our health, but we know very little about how these short bouts of incidental activity translate to health benefits," said the study's senior author Professor Emmanuel Stamatakis from the University of Sydney's Charles Perkins Centre.

In a study published in The Lancet Public Health today, a University of Sydney led team of international researchers with collaborators from University College London, University of Glasgow, University of Edinburgh, Loughborough University and University of Oxford set out to answer that question.

They used wrist-worn wearables data from the UK Biobank and machine learning to analyse the seven-day incidental physical activity patterns of 25, 241 UK adults aged 42 to 78, down to a 10-second time window. They then linked these physical activity micropatterns with participants' health records, following them for close to eight years to identify how length and intensity of physical activity bouts were linked to health status.

In this cohort of people who self-reported no participation in exercise or sport they found;

• 97% of incidental physical activity was accrued in bouts lasting <10 minutes
• Short bouts of <10 minutes at a moderate to vigorous intensity were associated with a steep decrease in major cardiac events (heart attack/stroke) and death by any cause.
• Moving consistently for at least 1 to 3 minutes was associated with significantly more benefit (29% lower) than very short bouts <1 minute.
• The longer the bouts the better (e.g., accrued in 2 minutes vs 30 seconds), regardless of total activity levels.
• The higher the % of vigorous activity in each bout the better -- those who huffed and puffed for at least 15% of the bout (roughly 10 seconds per minute) saw the greatest benefit.
• Bouts <1 minute were also associated with benefits if the above 15% vigorous activity rule was applied.

"This study suggests people could potentially reduce their risk of major cardiac events by engaging in daily living activities of at least moderate intensity where they are ideally moving continuously for at least one to three minutes at a time. In fact, it appears that this can have comparable health benefits to longer bouts lasting 5 to 10 minutes," said lead author Dr Matthew Ahmadi, Postdoctoral Research Fellow at the University of Sydney's Charles Perkins Centre.

"The take-home message here is any type of activity is good for your health, but the more effort you put into those daily tasks and the longer you keep up that energy, the more benefits you are likely to reap," said Professor Stamatakis.

"If you are huffing and puffing and unable to hold a conversation for some of that time you have hit the sweet spot."

The observational nature of the study means researchers cannot prove a cause-and-effect relationship with certainty. However, the researchers made extensive use of the UK Biobank's baseline health information allowing them to account for a number of factors such as diet, smoking, alcohol consumption, sleep and sedentary time. They also took precautionary measures against the potential effects of reverse causation, whereby poor health may influence activity patterns, by excluding those who had a cardiac event within five years of the wearables measurement, high frailty, and poor self-rated health.

Why do we need to know more about incidental activity?

Fewer than one in five middle-aged adults engage in regular exercise. There are a number of reasons for this including cost, time commitment, health status and access to facilities or infrastructure, but the fact remains that most people are not meeting recommended physical activity guidelines.

"The idea of accruing short bouts of moderate to vigorous activity through daily living activities makes physical activity much more accessible to people who are unwilling or unable to take part in structured exercise," said Dr Ahmadi. "But as we see in this data, the length and the vigour people put into these incidental activities matters."

The researchers say the study also provides some of the first direct evidence to support the idea that movement doesn't have to be completed in continuous 10 minute bouts to be beneficial -- a widely held belief until the World Health Organization removed this from their physical activity guidelines in 2020, instead focusing on the idea that 'every move counts towards better health'.

The researchers write: "If verified in future research, our findings could inform future public health messaging targeting the general population raising awareness of potential health benefits from short physical activity bouts in everyday life, especially for adults who do not or cannot exercise."