Reducing vigorous exercise by a few minutes a day raises cancer risk by 15 per cent, University College London researchers have found.
The finding suggests that choosing not to run for the bus or swapping visits to the gym for evenings in front of the television could prove deadly for older adults.
University College London, a public research university located in the UK capital, led the study published in the medical journal BMC Medicine. Researchers warned that people should maintain physical activity throughout their lives and avoid easing up as they age, as even minor reductions in movement can harm health.
Cancer risk linked to small changes in daily routine
The experts analyzed data from 59,218 volunteers from the UK Biobank database, a major biomedical research resource tracking half a million UK participants. The cohort had an average age of 61.7 years, and 55 per cent were female.
Over an eight-year follow-up period, 2,385 cancers occurred within the group. Investigators examined the duration participants spent sleeping, standing, engaging in sedentary behaviors such as watching television, and performing physical movement at various intensities.
The findings demonstrated that higher overall movement correlated with lower cancer risk. Replacing 15 minutes of sleep or sedentary behavior with 15 minutes of physical activity was associated with a 2 per cent reduction in cancer risk. Conversely, replacing 30 minutes of physical activity of any intensity with 30 minutes of sedentary behavior raised cancer risk by 8 per cent.
Dr John Mitchell, the lead author of the study from University College London, said: "Our study showed that there's an increased risk of cancer for those who spend a lot of time sitting down."
He added: "We also explored what might happen if people leading active lives reduced their levels of physical activity and found that they also face a higher cancer risk."
Referring to the 15 per cent raised danger, Dr Mitchell said: "Our study showed losing two to three minutes per day of vigorous activity and replacing it with sitting down, sleep or light activity increased their cancer risk."
Dr Mitchell noted: "Examples of vigorous activity (anything which elevates your heart rate and makes you sweat) include sport, rushing up the stairs and carrying home heavy grocery bags. The take-home message is that for people already leading physically active lives, it's really important to maintain that level of activity as you get older."
Official activity guidelines and cancer prevention
Previous medical studies have established strong evidence linking higher levels of physical activity to reduced risks of several specific cancers, including bladder, breast and bowel cancer, which are among the most common cancers diagnosed in the UK.
The National Health Service (NHS), Britain's publicly funded healthcare provider, recommends that adults aim for at least 150 minutes of moderate activity or 75 minutes of vigorous activity each week.
According to the NHS, examples of moderate activity include very brisk walking, everyday cycling or badminton. Vigorous activity includes hiking, tennis or jogging at 6mph or faster.
