Sitting for long periods without a break increases the risk of cancer. Here are some ways to counteract this

A sedentary lifestyle – prolonged and uninterrupted – is associated with a higher risk of death from cancer than the same total amount of time spent sitting, but spread over short sessions interspersed with movement, however minimal. In other words, the decisive factor is not the total amount of daily inactivity, but its pattern: continuous periods lasting more than thirty minutes produce different and more harmful physiological effects than equivalent but fragmented periods. This has been confirmed by one of the most extensive analyses ever conducted on the subject: a study recently published in PLOS Medicine and led by researchers at the University of Glasgow, in Scotland, who monitored over 90,000 participants for (on average) more than 12 years using wearable devices. The result is clear: every additional hour of prolonged sedentary behaviour throughout the day corresponds to a 9–10 per cent increase in the risk of cancer-related mortality, with an effect that accumulates progressively.

The types of cancer associated with prolonged sedentary behaviour cover a broad spectrum: those at highest risk include cancer of the oesophagus, kidney, liver, colorectal tract, lung, prostate and breast, along with cancers linked to obesity and type 2 diabetes. This second group is particularly significant from a biological perspective, as it suggests that prolonged inactivity acts via systemic metabolic changes – insulin resistance, low-grade chronic inflammation and changes in hormone levels – which are well-documented risk factors for cancer.

When the body remains inactive for long periods without interruption, blood glucose regulation deteriorates, levels of inflammatory markers rise and metabolic rate slows down, creating a physiological environment that promotes abnormal cell proliferation. These are cumulative exposures that build up over time, which explains why tracking trends over more than ten years is crucial.

In terms of practical implications, the most significant finding concerns the level of physical activity required to reduce the risk. Replacing one hour a day of prolonged sedentary behaviour with light physical activity (such as washing up, tidying or ironing) is associated with a 12% reduction in the risk of death from cancer. Replacing thirty minutes of inactivity with thirty minutes of walking at a moderate pace leads to an 8 per cent reduction, whilst five minutes of vigorous activity instead of five minutes of inactivity lowers the risk by 22 per cent. These figures challenge the prevailing approach of international physical activity guidelines, which are based on the concept of moderate or vigorous exercise for at least 150 minutes per week, and open up a structurally different perspective: systematically breaking up periods of sitting with activities already part of one’s daily routine is a protective strategy accessible to everyone, regardless of age or physical condition.

The study’s findings make it difficult to ignore a very common habit: people who exercise regularly but spend the rest of the day sitting for prolonged periods may not be as well protected as those who do not exercise intensively but frequently break up their sedentary periods. Structured exercise and the breaking up of inactivity appear to be partially independent factors in determining cancer risk, which calls into question the widely held belief that one hour of intense physical activity can offset eight hours spent at a desk.