A sedentary lifestyle is bad for you, we all know it. But it’s not just a question of how long we sit during the day: how and when we break up forced rest with activity breaks also seems to be a determining factor, at least as far as cancer prevention is concerned. This is suggested by a large epidemiological investigation published in Plos Medicinewhich analyzed the movement habits of 90,000 adults in the United Kingdom for about twelve years using wrist-worn accelerometers. The data demonstrate that remaining seated for uninterrupted blocks of more than thirty minutes significantly increases the incidence of oncological pathologies, while fragmenting the sedentary lifestyle with short intervals of light physical activity seems to play a protective role.
Sedentary lifestyle: prolonged or fragmented?
Researchers have distinguished sedentary lifestyle into two distinct behavioral patterns: the prolonged one, characterized by continuous periods of inactivity of at least thirty minutes, and the fragmented one, in which the periods of inactivity do not reach half an hour. The analysis of instrumental measurements showed that each additional daily hour spent without ever getting up for more than 30 minutes is associated with a 9 percent increase in the risk of cancer mortality and a 3 percent increase in the diagnosis of new tumors. The increase specifically concerns cancers related to obesity and type 2 diabetes, the incidence of which rises by 5 percent for every hour of continuous inactivity.
However, the picture changes radically when the sedentary lifestyle is broken up by short moments of activity, even very light ones, such as a simple walk. For every hour of fragmented inactivity recorded during the day, the study shows an 18 percent reduction in the risk of death from cancer and a 6 percent drop in the onset of the disease. “This is a biologically plausible scheme – underline the authors of the study – Various experimental research shows that interrupting rest periods with small breaks of physical activity improves the body’s metabolic response, compared to what is seen in the case of long periods of uninterrupted sedentary behavior”.
It doesn’t take much to do prevention
The statistical models developed in the study also highlight the important effect that small changes in daily habits can have. Replacing just one hour of prolonged sedentary lifestyle with one hour of light physical activity translates into a 12 percent reduction in cancer mortality and a 6 percent reduction in the probability of a cancer diagnosis.
Since this is an observational study, the results show statistical associations and do not establish a direct cause and effect relationship. However, the authors point to the large sample and the use of objective accelerometer measurements as strengths of the research. And they underline the absence of contraindications in adding a little more physical activity into your day.
“Current health guidelines focus heavily on moderate and vigorous exercise, but our findings demonstrate that even light activities such as walking should not be ignored,” concludes Frederick Ho, a researcher at the University of Glasgow who led the study. “I am sure that in the future clinical trials will help us move beyond generic advice and develop personalized strategies to interrupt sitting time.”