Substituting bouts of sedentary behavior with physical activity: adopting positive lifestyle choices in people with a history of cancer.

Purpose: To determine in people with a history of cancer, whether substituting sitting time with other daily activities (i.e., sleeping, walking, moderate and vigorous physical activity) was associated with changes in waist circumference (WC), an important surrogate marker of cardiometabolic risk.

Methods: Cross-sectional analyses from the Atlantic Partnership for Tomorrow's Health (Atlantic PATH) cohort was conducted using isotemporal substitution models to explore the associations of substituting sedentary time, physical activity behavior (International Physical Activity Questionnaire), or sleep (Pittsburgh Sleep Quality Index) with changes in WC. Analyses were conducted using sex-specific WC classifications.

Results: In 3,684 people with a history of cancer [mean age (SD) 58.2 (7.3) years; BMI 28.9 (5.2) kg m; 71% female], reallocating 10 min of sleep or sedentary time for 10 min of walking was associated with lower WC in women (p < 0.01). In men, PA intensity appeared to be more strongly associated with a reduced WC. Replacing 10 min of sedentary time with 10 min of moderate or vigorous PA and replacing 10 min of sleep with moderate PA were associated with a significantly reduced WC (p < 0.001). The largest effect was when 10 min of moderate PA was replaced with vigorous PA, a reduction in WC (p < 0.01) was evident.

Conclusion: For people with a history of cancer, adopting small but positive changes in lifestyle behaviors could help reduce WC and potentially offset negative health-related outcomes associated with higher WC. Further research is required to examine whether such an intervention may be acceptable and manageable among this population.