If you spend most of your working day seated at a desk, a few minutes of vigorous movement could be more useful than you think.
A new study suggests that replacing sedentary time with physical activity, particularly short bursts of vigorous movement, is associated with a lower risk of several cancers.
The study, published in July in BMC Medicine , analysed activity data from 59,218 men and women who were part of the UK Biobank. Participants wore activity trackers for a week, allowing researchers to measure how much time they spent sitting, standing and engaging in light, moderate or vigorous activity.
Researchers then examined their medical records over roughly eight years, looking at 13 cancers that have been associated with physical inactivity. They used statistical models to estimate what could happen if participants replaced some of their usual sitting time with different types and intensities of physical activity.
Standing was associated with lower cancer risk compared with remaining seated, but movement appeared to have a stronger association. Light activity was associated with greater benefits than standing, while vigorous movement showed the strongest association.
The study found that about three minutes of vigorous activity was associated with a similar reduction in cancer risk as about 90 minutes of light-intensity movement.
Vigorous activity in the study included movements that substantially increased breathing and heart rate, such as rushing up stairs or running to catch public transport.
For Riya Shah, a cancer specialist physiotherapist at Performance Medicine Kenya, the findings reinforce a broader message about the importance of movement throughout the day.
“Regular movement is one of the most important modifiable lifestyle factors we can influence across the cancer continuum, from prevention, through treatment and recovery, and into survivorship,” she says.
Shah says people often think of exercise as something that has to happen in a gym or as a structured workout, yet the body benefits from movement throughout the day. “Our bodies are designed to move throughout the day,” she says.
There is already evidence linking higher levels of physical activity with a lower risk of several cancers, particularly breast and colorectal cancer, she said. Physical activity is also associated with better cardiovascular and metabolic health.
For someone who spends eight or more hours sitting at work, Shah says the focus should not be solely on finding time for a workout before or after work.
Instead, people should also look at how they can interrupt long periods of sitting. “Don’t wait until the end of the working day to ‘do your exercise’. Build movement into the working day itself,” she says.
Her suggestions include standing up and walking around for a couple of minutes every 30 to 60 minutes, walking to speak to a colleague instead of sending a message where practical, taking the stairs, walking while making a phone call, getting up to refill a water bottle and having walking meetings where possible.
Standing, she says, is certainly better than remaining completely sedentary, but ideally people should move rather than simply switch from sitting to standing.
“Even a short walking break can increase muscle activity, circulation and energy expenditure,” she says.
It does not necessarily require a gym, running track or exercise equipment.
Shah says climbing several flights of stairs, walking quickly uphill, carrying heavy shopping, cycling quickly or running to catch a matatu can potentially qualify, depending on how hard the activity makes a person work.
“Exercise doesn’t have to look like exercise,” she says.
For one person, climbing several flights of stairs may constitute vigorous activity, while for someone who is fitter, the same activity may only be moderate.
A useful indicator, Shah says, is breathing. During vigorous activity, breathing and heart rate increase substantially and a person may only be able to say a few words before needing another breath.
However, she cautioned against interpreting the study as suggesting that three minutes of exercise a day is all a person needs.
The study was observational, meaning it identified an association between physical activity and cancer risk but did not prove that the short bursts of vigorous movement directly prevented cancer.
Shah says the finding should instead be viewed as an encouraging message for people who currently do little physical activity.
“If you currently do very little activity, small amounts of purposeful movement can still matter,” she says.
Those short bursts can be a starting point and can gradually be built upon, she adds.
There are also possible biological explanations for why physical activity may influence cancer risk. During vigorous movement, heart rate, blood flow, breathing and muscle glucose uptake increase. Exercise can also influence insulin sensitivity, metabolic health, inflammation, body composition and the immune system.
Shah says researchers are also studying how exercise mobilises immune cells, including natural killer cells, which are involved in identifying and responding to abnormal cells.
“Physical activity is important, but it doesn’t eliminate other established risk factors such as tobacco exposure, alcohol consumption, unhealthy body weight and diet,” she says.
For people with sedentary jobs, her advice is therefore simple: move whenever there is an opportunity.
Walk during a phone call. Take the stairs. Walk part of the journey where practical. Break up long periods of sitting. Add some brisk walking to the day and incorporate strength exercises such as squats, calf raises, glute bridges or resistance exercises at least twice a week.
Rather, movement can be accumulated throughout the day, from the journey to work and the office stairs to household tasks and short bursts of faster activity.
“Don’t aim for perfection, aim to avoid sitting continuously for hours at a time,” Shah says.
