Table 1.

General information about the included studies, including authors, year of publication, country, title, journal, funding sources.

Author, Year	Country	Title	Journal	Main Objective	Funding
Toth et al., 2018 [19]	USA	Video-recorded validation of wearable step counters under free-living conditions	Medicine & Science in Sports & Exercise	To investigate the step-count accuracy of several consumer- and research-grade activity monitors across all waking hours of 1 day.	This study was not funded
John et al., 2018 [36]	USA	“What is a Step?” Differences in how a step is detected among three popular activity monitors that have impacted physical activity research	Sensors	To compare manually counted steps during treadmill walking with those from the hip-worn Digiwalker SW200 and Omron HJ720ITC, and steps from hip- and wrist-worn GT3X+ and GT9X monitors processed using ActiLife software.	Not mentioned
Ata et al., 2018 [34]	USA	Clinical validation of smartphone-based activity tracking in peripheral artery disease patients	Digital Medicine	To assess the feasibility of the 6MWT app, “VascTrac,” to serve as a platform for performing 6 min walking tests in patients with PAD by (1) evaluating the accuracy of the iPhone’s step- and distance-tracking algorithms in the peripherical artery disease population, and (2) assessing the concordance of the iPhone algorithms with the ActiGraph GT9X.	Spectrum Stanford Predictives and Diagnostics Accelerator and the Stanford Precision Health and Integrated Diagnostics Center
Tedesco et al., 2019 [39]	Ireland	Accuracy of consumer-level and research-grade activity trackers in ambulatory settings in older adults	Plos One	To investigate the validity of different activity trackers in the estimation of step count, distance walked, and heart rate across a number of walking/household/sedentary activities recreated in a lab environment in a cohort of older adults.	This publication developed from research supported by EU H2020 funded project ProACT under grant agreement No. 689996. Aspects of this work were supported in part by a research grant from Science Foundation Ireland (SFI) and co-funded under the European Regional Development Fund under Grant Number 13/RC/2077. Aspects of this work were supported in part by INTERREG NPA funded project SenDOC.
Ho et al., 2019 [35]	China	Correction of estimation bias of predictive equations of energy expenditure based on wrist/waist-mounted accelerometers	PeerJ	To modify the traditional EE estimation equation: Freedson VM3 Combination, 2011 (ActiGraph, 2018), which is suitable for devices worn on different parts of the body.	Ministry of Science and Technology, Taiwan, under Grant MOST 107-2410-H-179-007.
Lynn et al., 2020 [37]	USA	Step-counting validity of wrist-worn activity monitors during activities with fixed upper extremities	Journal for the Measurement of Physical Behaviour	To examine the step-counting accuracy of wrist-worn activity monitors (Fitbit Charge HR 2, ActiGraph, Apple Watch Series 4) during various functional physical activities that require walking with the upper extremities fixed.	Not mentioned.
Mora-Gonzalez et al., 2022 [38]	USA	A catalog of validity indices for step counting wearable technologies during treadmill walking: the CADENCE-adults study	International Journal of Behavioral Nutrition and Physical Activity	To expand a previously published child/youth catalog of validity indices to include adults (21–40, 41–60, and 61–85 years of age) assessed across a range of treadmill speeds (slow [0.8–3.2 km/h], normal [4.0–6.4 km/h], fast [7.2–8.0 km/h]), and device locations (ankle, thigh, waist, and wrist)	The CADENCE-adults study was supported by NIH NIA Grant 5R01AG049024.
Anens et al., 2023 [33]	Sweden	Validity and reliability of physical activity measures in multiple sclerosis	Physiotherapy Theory and Practice	To evaluate the validity and test–retest reliability of different measures of physical activity in patients with multiple sclerosis.	Norrbacka Eugeniastiftelsen; ALF funding; P. O. Zetterling Foundation.