Interspersing physical activity throughout the day, rather than engaging in prolonged sedentary behavior, is associated with a reduced risk of cancer death, according to an observational study conducted by researchers from the University of Glasgow. The findings suggest that how individuals sit, not just the duration, may play a role in cancer mortality.
The study, published in PLOS Medicine, analyzed data from over 91,000 participants in the U.K. who wore movement-tracking devices for seven days. Researchers monitored the health outcomes of these volunteers for approximately 12 years.
Researchers defined prolonged sedentary behavior as any period lasting at least 30 minutes, during which at least 90% of the time was spent sitting. Interrupted sitting was defined as sessions shorter than 30 minutes or those broken up by brief periods of physical activity.
According to the study, each additional hour per day of prolonged sedentary behavior was linked to a 10% increase in cancer death risk. Conversely, replacing one hour of sitting with light physical activity, such as walking or household chores, was associated with a 12% lower risk of cancer death. Replacing 30 minutes of sitting with moderate activity showed an 8% reduction in risk, and even five minutes of vigorous activity was linked to a 22% lower risk.
Experts caution that the study cannot definitively prove causation, as the participants may not be representative of the general population. The activity monitors also captured behavior only during a limited period and did not account for the context of sedentary behavior, such as work, television viewing, or driving.
Dr. Georgia Spear, chief of breast imaging at Northwestern Medicine, who was not involved in the study, commented that existing research has associated sedentary behavior with obesity, diabetes, cardiovascular disease, and several types of cancer. "While it does not prove that sitting causes cancer, it suggests that long, uninterrupted periods of sitting are associated with a higher risk of cancer mortality," Spear stated. "The findings reinforce existing public-health recommendations that regular movement throughout the day is an important component of cancer prevention."
Spear suggested practical strategies to reduce sedentary time, including standing and moving every 30 to 60 minutes, taking short walking breaks, using stairs, walking during phone calls, and incorporating light activity throughout the day. She noted that these habits, combined with regular exercise, a healthy weight, limited alcohol consumption, not smoking, and recommended cancer screenings, can contribute to reducing the risk of various chronic diseases, including breast cancer.
Authors of the book "Walk," Dr. Courtney Conley and Dr. Milica McDowell, also emphasize the broad benefits of walking for physical and mental health, referring to it as "Vitamin W." They suggest increasing daily steps and incorporating "movement snacks" can boost longevity and overall wellness.