Sex-differences in relation to the association between patterns of physical activity and sedentary behavior with frailty

Objective: To investigate the sex-difference in relation to the association between moderate-vigorous physical activity (MVPA) and sedentary time (ST) patterns with frailty. Method: Accelerometry from >= 50 year olds from the National Health and Nutrition Examination Survey (2003-04/2005-06 cycles) were included. Bouted and sporadic MVPA were defined as MVPA in >= 10 min or < 10 min durations, respectively. MVPA was analyzed based on meeting 0 %, 1-49 %, 50-99 %, and >= 100 % of the physical activity guidelines of 150 min/week. A duration of >= 30 minutes defined prolonged ST. The frequency (>= 1 min interruption in ST), intensity and duration of breaks from ST were calculated. A 46-item frailty index (FI) quantified frailty. Multivariable linear regression models adjusted for demographics, total sedentary time, and accelerometer wear time. Results: There were 1143 females and 1174 males available for analysis. Bouted MVPA was associated with lower frailty levels; the association peaked at meeting 50-99 % of the guidelines in females and >= 1.0 % in males (p = NS for sex-interaction). Meeting a higher proportion of the guidelines through sporadic MVPA was significantly associated with a lower FI in males only (p = NS for sex-interaction). Prolonged ST bouts were associated with worse frailty in females but not males (p < 0.05 sex-interaction). Average break intensity was associated with a lower FI in both sexes, whereas, total sedentary breaks were not (p = NS for sex-interaction). Average break duration was associated with frailty in males (p = NS for sex-interaction). Conclusion: Prolonged ST was more detrimentally associated with frailty in females than males, which could influence tailored movement prescriptions and guidelines.