Ecological momentary pain and physical activity volume and patterns in older adults with chronic multisite pain

Chronic multisite musculoskeletal pain is prevalent in older adults and contributes to disability, partly through restriction and dysregulation of physical activity (PA). Prior studies have relied primarily on static pain measures and summary PA metrics, leaving time-varying pain-activity relationships poorly understood. This observational PRIME pilot study examined associations of baseline and time-varying pain characteristics with PA volume, fragmentation, and diurnal activity patterns in older adults with chronic multisite pain.

Thirty community-dwelling adults aged 65 years or older completed 14 days of wrist-worn accelerometry and ecological momentary assessment (EMA) of pain four times daily. PA outcomes included total activity counts/day (TAC), activity fragmentation, active minutes/day, and diurnal patterns. Linear regression and mixed-effects models examined associations of pain characteristics with PA, adjusting for age and sex.

EMA adherence was high (96% prompt completion). Back pain at baseline was associated with lower TAC (β = - 388,910, p = 0.029), fewer active minutes (β = - 74.5, p = 0.016), greater fragmentation (β = 5.38%, p < 0.001), and reduced afternoon/evening activity. Higher momentary pain severity was associated with lower activity from wake-up to the morning prompt (β = - 15,688, p = 0.045) and a positive trend during the overnight interval (β = 12,169, p = 0.087). Mixed-effects models showed significant three-way interactions among overall pain severity, time (linear and quadratic), and weekday/weekend status (p < 0.04), indicating contextual modulation of diurnal PA trajectories.

Pain-activity relationships in older adults are heterogeneous and context-dependent. Integrating EMA with accelerometry may inform personalized interventions to maintain mobility and physical functioning.