A new study has provided evidence that short bouts of incidental activity could reduce risk of heart attack, stroke and even premature death – but the length of activity and intensity matters. The study was led by a University of Sydney team with international collaborators including members of Oxford Population Health, has been published in The Lancet Public Health today.
The researchers 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 ten-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 less than ten minutes
- Short bouts of less than ten 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 one to three minutes was associated with significantly more benefit (29% lower) than very short bouts less than one minute.
- The longer the bouts the better (e.g., accrued in two minutes vs 30 seconds), regardless of total activity levels.
- The higher the percentage of vigorous activity in each bout the better – those who huffed and puffed for at least 15% of the bout (roughly ten seconds per minute) saw the greatest benefit.
- Bouts of less than one1 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 five to ten minutes.' said lead author Dr Matthew Ahmadi, Postdoctoral Research Fellow at the University of Sydney’s Charles Perkins Centre.
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.
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. As a result, most people are not meeting recommended physical activity guidelines.
Aiden Doherty, Professor of Biomedical Informatics at Oxford Population Health said ‘This study is yet another imaginative use of the UK Biobank wearables resource. In the recent past it would not have been possible to investigate whether incidental activity is associated with health benefits because we simply did not have the tools available to measure incidental activity at scale. It is clear that we need large-scale wearable measurements in major studies across the globe to further our understanding of the causes and consequences of physical activity patterns.’
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 ten 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.'