Table 2.

Measurement tools to assess physical activity [73, 110]

	Energy expenditure	Physiological measures	Motion sensors	Questionnaires and logs
Objective/ subjective	Objective	Objective	Objective	Subjective
Examples	Indirect calorimetry, doubly labelled water and direct observation	Heart rate monitoring	Accelerometers and pedometers	Questionnaires, logs and diaries
Basis	Lab-/hospital-based	Lab-/hospital-based and day-to-day life	Day-to-day life	Lab-/hospital-based and day-to-day life
Advantages	Gold standard High validity and reliability	Relatively inexpensive Low burden for patients/participants High validity for moderate-to-vigorous activities Assists in physical activity and exercise interventions	Relatively inexpensive Low burden for patients/participants Easy to wear 24 h 7 days per week Provides detailed information about intensity, frequency and duration Applicable to large number of individuals Pedometers are intuitive, understandable and could motivate individuals Might increase daily physical activity	Low cost Questionnaires have low burden Applicable to large number of individuals Assessment of different domains and dimensions Questionnaires are valid to assess structured physical activity Logs/diaries provide a good overview of physical activity and energy expenditure Easy to implement in clinical practice
Disadvantage/s	Expensive Requires highly trained personnel Limited practical utility High participant burden	Lower validity for light-intensive physical activities and sedentary behaviour Affected by sympathetic reaction on for example emotions status, temperature and caffeine consumption Limited use in patients using medication affecting heart rate responses (e.g. β-blockers) or in patients suffering from cardiac autonomic neuropathy. In this case, the intensity can be determined in combination with the Borg Scale	Not able to distinguish between types of activities Depending on the placement, it neglects upper-body activities and differs in validity For accelerometers, data reduction, transformation and processing takes time Pedometers are less valid for energy expenditure Might increase daily physical activity	Questionnaires are subject to recall bias and socially desirable answers Questionnaires have low validity in incidental physical activity Logs/diaries have a very high burden on participants, patients and personnel Need to be population and culture-specific
Requirements	Trained personnel, expensive equipment and specific analytic skills/knowledge	Familiarization to protocol, data extraction and analyses	Familiarization to protocol, data extraction and analyses	No specific requirements
Practical considerations	Reliant on technical experts Require calibration Lower feasibility	Patients could develop skin irritation during prolonged wearing Calibration requires technical expertise	Patients may have sensitive skin Calibration requires technical expertise Recommend at least 7 days of monitoring Positioning of the monitor Record data in the highest resolution	Choosing the outcome of the self-reported tool necessary to answer the clinical or research question