Being more active in the morning and evening may reduce the risk of bowel cancer by 11%, according to a study that suggests the timing of peak activity could play a “crucial role” in warding off the disease.
Researchers said that highlighting specific times when physical activity was “most beneficial” could pave the way for targeted cancer prevention strategies. The findings were published in the journal BMC Medicine.
The study, led by experts from the University of Regensburg in Germany, used data from the UK Biobank to assess 86,252 people aged 42 to 79, who tracked their physical activity by wearing a device on their wrist known as an accelerometer.
Some 529 cases of bowel cancer occurred over a follow-up period of more than five years. Researchers highlighted four activity patterns: continuous daylong activity, activity late in the day, activity in the morning and evening, and activity at midday and at night.
They found two daily peaks in activity, at about 8am and 6pm, “was associated with reduced colorectal cancer risk, beyond the benefits of overall physical activity”.
People active in both the early and late parts of the day had an 11% lower risk of colorectal cancer, compared with 6% for daylong activity and no change for middle of the day and the night. Data from those who were active later in the day only was inconclusive.
The findings held true even when considering factors such as smoking, shift work and other variables that could affect a person’s cancer risk, the study found.
Prof Dr Michael Leitzmann, chair of the department of epidemiology and preventive medicine at Regensburg, was the lead investigator for the study.
He said: “Our study highlights that not only is physical activity important for reducing colorectal cancer risk, but the timing of peak activity throughout the day could play a crucial role.
“By identifying specific times – early morning and late day – when physical activity is most beneficial, our findings open new avenues for targeted prevention strategies.
“If confirmed by future research, this could provide a simple yet impactful way for individuals to further reduce their cancer risk through the timing of their exercise.”
Bowel cancer, also known as colorectal cancer, can develop anywhere in the large bowel, which includes the colon and rectum. It is one of the most common cancers worldwide.
The Dawson’s Creek star James Van Der Beek disclosed on Sunday he had been diagnosed with the disease.
Dr Helen Croker, assistant director of research and policy at the World Cancer Research Fund, which funded the study, said: “Being physically active is one of our cancer prevention recommendations, and we know that this cuts cancer risk. These intriguing new findings offer potential for developing more specific recommendations, including patterns and timing of physical activity, for reducing cancer risk.”
