Level of agreement between physical activity levels measured by ActiHeart and the International Physical Activity Questionnaire in persons with intellectual disability

Purpose: The purpose of this study was to determine the level of agreement between objective physical activity (PA) (ActiHeart®) and subjective proxy-respondent International Physical Activity Questionnaire-short version (IPAQ-S) data in adults with intellectual disabilities (IDs). Method: Fifty-eight participants wore ActiHeart® monitors for seven consecutive days. Caregivers of each participant completed the IPAQ-S on behalf of the participant. Total PA, time spent in light, moderate, and vigorous activity as well as time spent being sedentary were assessed by the IPAQ-S and the ActiHeart®. Results were compared by means of correlation analyses. The level of agreement was presented with Bland–Altman plots. Results: Objective PA (ActiHeart®) was higher (225.57 ± 91.96 min/week) than IPAQ-S PA reported by care-givers (177.06 ± 309.17 min/week). Weak significant correlations were observed between the ActiHeart® and IPAQ-S instruments for sedentary behavior (r = 0.31; p = 0.04); no significant correlations for light (r= −0.04; p = 0.8), moderate (r= −0.07; p = 0.63), or vigorous PA (r= −0.2; p = 0.18) were found. Limited agreement between objectively determine PA (ActiHeart®) and IPAQ-S was found. Conclusion: IPAQ-S is inaccurate when determining PA in persons with ID as it significantly underestimates the true levels of PA in this cohort. Implications for Rehabilitation Persons with intellectual disability (ID) report insufficient physical activity for health benefits. Physical activity is often determined by means of subjective proxy reporting. Objective physical activity measurements by means of combined heart rate and accelerometer are necessary to determine accurate levels of physical activity in persons with ID. Exercise interventions should be based on objective physical activity measurements.