The Measured Physical Functioning Index Describing Population Level Physical Ability

Background: Physical functioning is traditionally assessed and presented as self-reported measures, which have shown either improvement or stability during the last decades at population level. On the other hand, objectively measured, performance-based measures of physical functioning have indicated increased body weight and decreased physical fitness. Therefore, there is a need for objective, measured total physical functioning index (MePFIX). Methods: The MePFIX was developed from the data of 5238 working-aged adults (60% women) who took part in the FINFIT studies from years 2017 and 2021. The outcomes of measured body composition, cardiorespiratory fitness, muscular fitness, physical activity, stationary behavior, and time in bed were used to create the MePFIX. Results: The best performing index contained the fol-lowing measures: waist circumference, estimated maximal oxygen consumption, modified push-up, mean of daily 1-minute metabolic equivalent, high-movement time in bed, lying and reclining during waking hours >20-min bouts, standing, daily step count, moderate-to-vigorous physical activity in absolute terms, and light physical activity relative to fitness. Conclusions: The developed MePFIX is based on population-based data, containing measured outcomes of body composition, cardiorespiratory fitness, muscular fitness, physical activity, sedentary behavior and time in bed. The index could serve as an objective indicator of physical functioning among the target population. The MePFIX can be used as a figure of merit of measured physical functioning for research community and policy makers both at cross-sectional and at longitudinal analyses.