Reallocating time to sleep, sedentary time, or physical activity: Associations with waist circumference and body mass index in breast cancer survivors

Terry Boyle, Jeff K. Vallance, Matthew P. Buman, Brigid M. Lynch

    Research output: Contribution to journalJournal Articlepeer-review

    29 Citations (Scopus)

    Abstract

    Background: Moderate-to-vigorous intensity physical activity (MVPA) is inversely associated with waist circumference and body mass index (BMI) among breast cancer survivors. Limited research has focused on behaviors that account for larger portions of the day [sleep, sedentary time, and light-intensity physical activity (LPA)]. We investigated the interdependent associations of selfreported sleep, objectively assessed prolonged and short bouts of sedentary time, total LPA, and total MVPA with waist circumference and BMI. Methods: A cross-sectional sample of breast cancer survivors (N = 256, mean age = 60 years; mean time since diagnosis = 3 years) wore an Actigraph GT3X+ accelerometer during waking hours for 7 days. Participants completed the Pittsburgh Sleep Quality Index and self-reported their waist circumference, height, and weight. An isotemporal substitution approach was used in linear regression models to explore the associations of reallocating time to sleep, sedentary and active behaviors on waist circumference, and BMI, after adjusting for potential confounders. Results: Reallocating 30 minutes to MVPA was significantly associated with lower waist circumference when allocated from sleep (-2.50 cm), prolonged sedentary time (-2.51 cm), or LPA (-2.71 cm). Reallocating 30 minutes of prolonged sedentary time to nonprolonged sedentary time was significantly associated with lower waist circumference (-0.94 cm). Similar results were observed for BMI. Conclusions: Reallocating 30 minutes to MVPA was associated with significantly lower waist circumference and BMI, as was reallocating 30 minutes of prolonged sedentary time to 30 minutes of nonprolonged sedentary time. Impact: Increasing MVPA levels and decreasing time spent in prolonged, unbroken sedentary bouts may be avenues for improving body composition in this population.

    Original languageEnglish
    Pages (from-to)254-260
    Number of pages7
    JournalCancer Epidemiology Biomarkers and Prevention
    Volume26
    Issue number2
    DOIs
    Publication statusPublished - 1 Feb. 2017

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