A brisk extra five-minute walk per day could potentially prevent many deaths. This is shown by new research based on data from more than 135,000 middle-aged and older adults. The study, conducted by researchers at the Norwegian School of Sport Sciences in collaboration with Uppsala University and others, has been published in The Lancet.
As confirmed by earlier research, physical activity has public health benefits. In the new study, researchers investigated how many deaths could potentially have been prevented by very small changes in the population’s activity level. They did this by studying the effect of increased physical activity and reduced sedentary time in more than 135,000 people in Norway, Sweden, the UK and the US. The mean age of the people included in the study was 64.
“Our results show that small changes in physical activity can be highly significant for public health, particularly for people who are physically inactive,” said Ulf Ekelund, professor at the Department of Sports Medicine at the Norwegian School of Sport Sciences, first author of the study.
The researchers studied how many deaths could have been prevented if people had increased their activity level with moderate physical activity or more. Moderate physical activity is comparable to walking at a speed of 5km per hour. They found that increasing moderate physical activity by five minutes per day could have prevented 10% of deaths. This calculation excluded the most active individuals.
Among the 20% who were least active, increasing moderate physical activity by five minutes per day could have prevented 6% of deaths. On average, this group was physically active for about two minutes per day.
In general, the individuals in the study averaged only around 28 minutes of moderate physical activity per day.
“While it was not surprising to see that the participants moved so little, it was surprising to see that the associations were so strong – that a five-minute increase in the activity level was associated with such a tangible decrease in mortality,” said Peter Nordström, professor of Geriatrics at Uppsala University, who was one of the authors of the study.
In their paper, the researchers also looked at sedentary time. They found that reducing sedentary time by 30 minutes per day could have prevented 7% of deaths in the entire population. On average, this group sits still for around 10 hours per day. The equivalent reduction among the most sedentary, who spend an average of about 12 hours per day sitting still, was approximately 3%.
The article is an observational study based on data from seven cohorts in Norway, Sweden and the US, along with the UK Biobank.
The participants had recorded their activity level using an accelerometer, a sensor attached to the hip that measures how much a person moves. Using the data collected, the researchers estimated how many deaths could potentially have been prevented by small daily increases of moderate to vigorous physical activity, or by reducing sedentary time. The average follow-up period was eight years.
The researchers emphasise that the published article is based on an observational study, which means it is not possible to draw direct conclusions about the causal link between higher physical activity and lower mortality risk.
“It’s not necessarily a case of causal links, this is a study that examines associations between an increased level of activity and the number of deaths that could potentially be prevented. There may be other explanatory models for the figures we see, for example, that the people who move more have a different heredity – in other words, that genes also play a role in how physically active a person is,” Nordström said.
Despite this, the researchers argue that their findings provide important evidence that small changes in physical activity and sedentary time can have substantial health benefits.
“The results should not be interpreted as recommendations for individuals. They are estimates of how many deaths could potentially be prevented if all inactive members of the population increased their activity by five minutes per day,” Ekelund said.
