The authors explored using the ActiGraph accelerometer to differentiate activity levels between participants in a physical activity (PA, n = 54) or “successful aging” (SA) program (n = 52). The relationship between a PA questionnaire for older adults (CHAMPS) and accelerometry variables was also determined. Individualized accelerometry-count thresholds (ThreshIND) measured during a 400-m walk were used to identify “meaningful activity.” Participants then wore the ActiGraph for 7 days. Results indicated more activity bouts/day ≥10 min above ThreshIND in the PA group than in the SA group (1.1 ± 2.0 vs 0.5 ± 0.8, p = .05) and more activity counts/day above ThreshIND for the PA group (28,101 ± 27,521) than for the SA group (17,234 ± 15,620, p = .02). Correlations between activity counts/hr and CHAMPS ranged from .27 to .42, p < .01. The ActiGraph and ThreshIND might be useful for differentiating PA levels in older adults at risk for mobility disability.
Leslie A. Pruitt, Nancy W. Glynn, Abby C. King, Jack M. Guralnik, Erin K. Aiken, Gary Miller and William L. Haskell
Leslie A. Pruitt, Abby C. King, Eva Obarzanek, Michael Miller, Mary O’Toole, William L. Haskell, Laura Fast, Sheila Reynolds and for the Activity Counseling Trial Research Group
Physical activity recall (PAR) reliability was estimated in a three-site sample of African American and white adults. The sample was sedentary at baseline and more varied in physical activity 24 months later. Intraclass correlation coefficients (ICCs) were used to estimate the number of PAR assessments necessary to obtain a reliability of 0.70 at both timepoints.
The PAR was administered ≤ 30 d apart at baseline (n = 547) and 24 months (n = 648). Energy expenditure ICC was calculated by race, gender, and age.
Baseline reliability was low for all groups with 4–16 PARs estimated to attain reliable data. ICCs at 24 months were similar (ICC = 0.54–0.55) for race and age group, with 2–3 PARs estimated to reach acceptable reliability. At 24 months, women were more reliable reporters than men.
Low sample variability in activity reduced reliability, highlighting the importance of evaluating diverse groups. Despite evaluating a sample with greater physical activity variability, an estimated 2–3 PARs were necessary to obtain acceptable reliability.