Vigorous Intermittent Lifestyle Physical Activity and Cancer Incidence Among Nonexercising Adults: The UK Biobank Accelerometry Study.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 37498576 · doi:10.1001/jamaoncol.2023.1830
What was done
This prospective cohort study analyzed 22,398 self-reported nonexercising adults (mean age 62.0 years; 54.8% women; 96.0% White) from the UK Biobank accelerometry subsample. Participants wore wrist-worn accelerometers to measure daily vigorous intermittent lifestyle physical activity (VILPA) in bouts lasting up to 1 and up to 2 minutes. Participants were followed for a mean of 6.7 years (149,650 person-years) for total incident cancer and physical activity-related cancer (13 specific sites). Hazard ratios were adjusted for age, sex, education, smoking, alcohol, sleep duration, diet, parental cancer history, and other physical activity levels.
What was found
Over follow-up, 2,356 total cancer events and 1,084 physical activity-related cancer events occurred. Most VILPA (92.3%) occurred in bouts under 1 minute. Compared to zero VILPA, a median daily duration of 4.5 minutes per day (in bouts up to 1 minute) was associated with a hazard ratio (HR) of 0.80 (95% CI, 0.69–0.92) for total cancer and 0.69 (95% CI, 0.55–0.86) for physical activity-related cancer. The minimal dose for 50% of the maximum risk reduction was 3.4 minutes per day for total cancer (HR 0.83; 95% CI, 0.73–0.93) and 3.7 minutes per day for physical activity-related cancer (HR 0.72; 95% CI, 0.59–0.88).
Why it matters
These findings suggest that even brief bursts of vigorous physical activity embedded in daily life—totaling fewer than 5 minutes per day—are associated with substantial reductions in cancer risk among individuals who do not participate in structured exercise.
Limits
The study is observational, precluding causal inference and leaving open the possibility of reverse causation or residual confounding (e.g., undiagnosed subclinical disease lowering activity levels). The cohort was 96% White, limiting generalizability to other racial and ethnic groups, and accelerometry was assessed over a single baseline monitoring period.