Comparison of activPAL and ActiGraph measured moderate to vigorous physical activity in people with COPD

OBJECTIVE: ActiGraph accelerometers are commonly used to assess moderate-to-vigorous physical activity (MVPA), but there are concerns about missing data due to compliance issues with hip-worn devices. ActivPAL devices are worn 24 hours/day on the anterior thigh, minimizing missing data, but activPAL software does not directly estimate MVPA. This study aimed to evaluate the agreement between MVPA derived from activPAL (using five methods) and ActiGraph data (using two methods) among individuals with chronic obstructive pulmonary disease (COPD). APPROACH: In this secondary analysis, 148 inactive adults aged ≥50 years with COPD wore an activPAL3 on the thigh and an ActiGraph GT9X on the hip concurrently for 7 days. MVPA was estimated from activPAL using five methods: 1) metabolic equivalents, 2) ≥75 steps/min, 3) ≥100 steps/min, 4) vector magnitude (VM) counts, and 5) vertical-axis counts, and from ActiGraph using Freedson VM3 (2011) and Evenson (2023) VM cut-points, 60s epochs, and normal filters. We assessed agreement between activPAL and ActiGraph MVPA using concordance correlation coefficients (CCCs), two one-sided t-tests (TOST), and Bland-Altman plots. MAIN RESULTS: Compared with ActiGraph MVPA using Freedson VM3, CCCs ranged from 0.51 to 0.53 across activPAL methods, except for ≥100 steps/min (CCC=0.42); four of five activPAL methods were equivalent at a ±8 min/day equivalence margin. Compared with ActiGraph MVPA using Evenson, CCCs ranged from 0.20 to 0.25 across activPAL methods, and no activPAL method was equivalent. SIGNIFICANCE: ActivPAL MVPA showed moderate group-level agreement and equivalence when compared to ActiGraph MVPA using Freedson VM3. Findings suggest activPAL may estimate group-level MVPA in this population, though further research is needed to validate this approach for individual-level MVPA.