A comparison of physical activity (PA) assessment tools across levels of frailty

Purpose: Determine which PA assessment tools are most closely related to frailty and whether PA is different across levels of frailty. Methods: Fifty community-dwelling Greek older women (63-90. years) participated in this study. PA was measured objectively over 10. h using an accelerometer, a heart rate (HR) monitor, a portable electromyography (EMG) unit, and a global positioning system (GPS) and subjectively using the short version of the Minnesota Leisure Time Activity Questionnaire (MLTAQ). Participants were divided into three tertiles based on level of frailty as calculated from a Frailty Index (FI): low FI group (<0.17 FI); intermediate FI group (0.17-0.38 FI); and high FI group (>0.38 FI). Results: Accelerometer step counts had the strongest correlation with frailty and were different across levels of frailty. The percentage of time engaged in PA was 31 ± 15% when PA was determined using an accelerometer. Forty-five percent of the variability in the FI was explained by a combination of PA assessment tools including; accelerometer, EMG, GPS, and MLTAQ. The individual contribution of EMG determined activity from the biceps brachii (BB) to the FI prediction was 16%. Accelerometer contributed an additional 10% and time engaged in PA, as assessed with the MLTAQ, added an additional 6% to the prediction of FI score. Conclusions: PA assessment tools, when used in combination, provide important information about the PA accumulation of older women across levels of frailty.