Self-reported activity and accelerometry in 2 behavior-maintenance trials

Abstract

Objectives: To compare between accelerometry (MVPA-A) and self-reported activity (MVPA-SR) in activity-maintenance (Keep Active Minnesota; KAM) and weight loss-maintenance (Keep It Off; KIO) trials.

Methods: Linear regression estimated moderation of study, treatment, or time on MVPA-A and MVPA-SR associations.

Results: MVPA-A was similar between studies (KAM 119 minutes, KIO 112 minutes, p = .555), whereas MVPA-SR differed significantly (KAM 350 minutes, KIO 87 minutes, p < .0001). Only study moderated correlation between MVPA-A and MVPA-SR. MVPA-SR better predicted MVPA-A in KIO relative to KAM (p = .023).

Conclusions: Results suggest that self-presentation bias may influence validity of self-report in intervention studies with activity as a primary outcome. Researchers should select self-report to assess activity dimensions that objective measures capture poorly.

Trial registration: ClinicalTrials.gov NCT00283452 NCT00702455.

Figures

Figure 1

Moderation of MVPA-SR vs. MVPA-A by Time, Treatment, or Study.

Figure 2

Bland-Altman Plot of MVPA-SR and MVPA-A, KIO Study.

Figure 3

Bland-Altman Plot of MVPA-SR and MVPA-A, KAM Study.

Figure 4

Moderation of MVPA-A vs. MVPA-SR by Time, Treatment, Study, and Interactions.