Objective versus subjective methods in the assessment of physical activity among office workers

Objective This paper explores the accuracy of different tools used to assess daily physical activity levels among office workers. The focus is on comparing objective accelerometer data with subjective self-report diaries.

Material and Methods 20 volunteers wore triaxial accelerometers (Axivity) for an average of 4.5 consecutive working days. Sensors were affixed to the neck C7-Th1 level paravertebrally. Accelerometers were configured at a sampling rate of 25 Hz ±4 g. Data was pre-processed using the OMGUI software and translated into activity levels using mathematical transformation steps. In parallel, participants manually completed daily activity diaries to provide subjective data. Statistical analysis of self-reported and accelerometer data was performed using Python. The study was funded by the framework of the Plan of the EU Recovery and Resilience Facility and the State budget (Nr. 5.2.1.1.i.0/2/24/CFLA/005), project ‘Multidisciplinary approach for the development of the sustainable habit of regular physical activity among sedentary workers’(Nr.RSU/LSPA-PA-2024/1-0013).

Results Participants were majorly able to correctly identify sedentary activity level (89.3% of reported sedentary activity was confirmed by accelerometer readings), however, only 9% of self-reported moderate activity levels (walking in the park, etc) were reported correctly according to the sensor data. Moreover, none of the intense (intentional exercises, like gym or dance) was self-reported correctly, suggesting that either the location of the sensor was not fit for the purpose of identifying intense activity levels or that people who lead predominantly sedentary lifestyle tend to overestimate intensity of the undertaken activity majorly. Additionally, 10% of self-reported sedentary activity has been identified to be of moderate intensity, suggesting pacing or fidgeting that participants overlook.

Conclusion Preliminary findings suggest that accelerometer-based measurements provide a more objective and consistent evaluation than self-reported data. Further research should clarify correlations between the tools and inform future workplace monitoring strategies.