Replacing sedentary time with physical activity and sleep: associations with quality of life in kidney cancer survivors.

Kidney cancer survivors spend large quantities of time sedentary and little time physically active, which negatively impacts quality of life (QoL). This study examined (1) the association of reallocating sedentary time to sleep, light physical activity (PA), or moderate-to-vigorous PA (MVPA) on QoL in kidney cancer survivors and (2) the threshold at which results are clinically meaningful. Kidney cancer survivors (N = 463) completed a survey including the Godin Leisure-Time Exercise Questionnaire, sitting time, sleep duration, and Functional Assessment of Cancer Therapy (FACT) scales. Isotemporal substitution analyses estimated associations of reallocating sedentary time to PA and sleep on QoL. Reallocating 10 min/day of sedentary time to MVPA was significantly associated with higher scores on the Trial Outcome Index-Fatigue (B = 0.60, SE = 0.25, p = 0.02), FACT-Fatigue (B = 0.71, SE = 0.32, p = 0.03), functional well-being (B = 0.18, SE = 0.08, p = 0.02), and fatigue subscales (B = 0.35, SE = 0.15, p = 0.02). Reallocating sedentary time to sleep was significantly associated with higher FACT-General (B = 0.15, SE = 0.08, p = 0.04) and functional well-being subscale (B = 0.06, SE = 0.03, p = 0.049) scores. Reallocating sedentary time to light PA was significantly associated with higher fatigue subscale scores (B = 0.46, SE = 0.23, p = 0.045). Kidney cancer survivors would need to reallocate a minimum of about 83, 200, and 65 min/day of MVPA, sleep, and light PA, respectively, for associations to be clinically meaningful. Reallocating sedentary time to MVPA, light PA, or sleep at higher doses is associated with better fatigue and physical aspects of QoL. Interventions should consider replacing sedentary time with MVPA or light PA in a gradual manner, and improve sleep quality for kidney cancer survivors.