Association Between Physical Activity and Stationary Time Variability and Frailty in Adults Meeting and Not Meeting Activity Guidelines

• Before adjustment for mean activity levels, higher MVPA variability was related to lower frailty among inactive adults. • Among stationary adults, higher stationary time variability linked to lower frailty. • Mean MVPA and stationary time may be more important than activity variability. • Lower MVPA and stationary variability was observed among frailer individuals. • Results were sensitive to accelerometer wear time. This study tested the hypothesis that greater variability in moderate-to-vigorous intensity physical activity (MVPA) and stationary time is associated with lower frailty among inactive (<150 min/week MVPA) and stationary (≥8 hours/day) adults, and with higher frailty among active (≥150 min/week MVPA) and non-stationary (<8 hours/day) adults. N=5945 (3061 females) community-dwelling adults (age: 51.9±18.5 years) from the National Health and Nutrition Examination Survey (NHANES 2003-2006) were included in this cross-sectional analysis. Frailty was measured with a 46-item index based on the deficit accumulation model and habitual activity, including average real variability, was derived from ActiGraph accelerometers. Among active and inactive individuals, there was no association between MVPA variability and frailty (both, p >0.455), but higher average MVPA was associated with lower frailty in both active (β=-0.0002, p =0.02) and inactive (β=-0.0036, p <0.001) adults. Higher stationary time variability was associated with higher frailty in stationary and non-stationary populations (both, p <0.001). These associations were non-significant when variability was expressed as a percentage of accelerometer wear time (both, p >0.741). Lower average stationary time was associated with lower frailty in non-stationary and stationary adults even when wear time was considered ( p <0.001). After accounting for accelerometer wear time, neither MVPA nor stationary time variability were associated with frailty, highlighting that overall activity may be associated with frailty rather than day-to-day accumulation patterns.