Convergent validity and responsiveness to change of the single-item physical activity measure were assessed in adults aged 60 years and older, at baseline (n = 205) and 6 months (n = 177) of a health promotion program, Choose to Move. Spearman correlations were used to examine associations between physical activity as measured by the single-item measure and the Community Health Activities Model Program for Seniors (CHAMPS) questionnaire at baseline and for 6-month change in all participants and for sex and age (60-74 years, and ≥75 years) subgroups. Effect size assessed responsiveness to change in physical activity for both tools. Baseline physical activity by the single-item measure correlated moderately with physical activity by the CHAMPS questionnaire in all participants and subgroups. Correlations were weaker for change in physical activity. Effect size for physical activity change was larger for the single-item measure than for the CHAMPS questionnaire. The single-item measure is a valid, pragmatic tool for use in intervention and scale-up studies with older adults.
Keywords: intervention trials; scale-up science; self-report questionnaire.