Table 1.

The summary of included studies (N=40 studies, ranked by health condition and alphabetically by author names).

Reference		Age (years), mean (SD)	Age (years), range	N	Sensor brand/ model	Number of sensors (placement)	MVPAa classification technique	Validation setting	Ground truth	Code availability
Healthy condition
	Ahmadi et al [50]	4 (0.9)	—b	31	ActiGraph GT3X +	2 (hip, wrist)	RFc and SVMd	Free-living	DOe	No
	Ahmadi et al [51]	4 (0.9)	—	31	ActiGraph GT3X +	2 (hip, wrist)	RF	Free-living	DO	Yes
	Ahmadi et al [52]	13.9 (3)	—	50	ActiGraph GT3X +	1 (hip)	RF	Lab	PREf	Yes
	Ahmadi et al [38]	4 (0.9)	—	31	ActiGraph GT3X +	2 (hip, wrist)	RF	Free-living	DO	Yes
	Ahmadi et al [53]	55.8 (12.4)	—	102	MEMS and ActiGraph GT9X	2 (both wrists)	RF	Lab and free-living	DO	No
	Ahmadi et al [53]	55.8 (12.4)	—	52	MEMS and ActiGraph GT9X	2 (both wrists)	RF	Lab and free-living	DO, ICg	No
	Ahmadi et al [53]	—	18-91	151	Axivity AX3	1 (wrist)	RF	Free-living	DO	No
	Andò et al [36]	NRh	—	NR	LSM9DS1	1 (chest)	k-NNi and RF	Lab	PRE	No
	Bai et al [54]	72.4 (7.1)	—	247	ActiGraph GT3X-BT	1 (wrist)	XGBoostj	Lab	IC	No
	Barua et al [34]	29 (0)	18-56	42	Samsung Galaxy S7	3 (pocket, backpack, hand)	1D-CNN-LSTMk	Lab	PRE	No
	Chen et al [55]	12.3 (1.0)	—	18	smartwatch “mumu”	1 (wrist)	SVM	Free-living	IC	No
	Chen et al [55]	24.9 (2.6)	—	24	smartwatch “mumu”	1 (wrist)	SVM	Free-living	IC	No
	Davoudi et al [56]	55.2 (17.8)	—	40	ActiGraph GT3X+ and Samsung smartwatch	2 (wrist)	RF	Lab	IC	No
	Doherty et al [57]	—	18-91	153	Axivity AX3	1 (wrist)	RF	Free-living	DO	No
	Ellingson et al [58]	23.9 (5.3)	—	49	ActiGraph GT3X+ and actiPAL	2 (hip, thigh)	ANNl and DTm	Lab	IC and PRE	Yes
	Ellingson et al [59]	23.5 (4.6)	—	51	ActiGraph GT3X+	1 (hip)	RF	Lab	IC	On request
	Farrahi et al [60]	27.5 (11.2); 13.7 (3.1); 27.2 (3.3)	20-30	22; 52; 9; 8	Hookie AM20; Actigraph GT3X+; Colibri inertial measurement unit; Xsens MTx inertial measurement unit	1 (hip); 2 (hip, wrist); 1 (wrist); 2 (wrists)	ANN	Lab	DO	No
	Farrahi et al [31]	—	18-91	151	Axivity AX3	1 (wrist)	BiLSTMn, RF, ANN, SVM, DT, and NBo	Free-living	DO	No
	Freedson et al [61]	38 (12.4)	—	277	ActiGraph GT1M	1 (hip)	ANN	Lab	IC	No
	Hagenbuchner et al [29]	4.8 (0.9)	—	11	ActiGraph GT3X +	1 (hip)	ANN	Lab	PRE	No
	Hibbing et al [62]	9.4 (2.1)	—	27	ActiGraph GT3X-BT	3 (hip, both wrists)	ANN and DT	Free-living	DO	On request
	Hibbing et al [62]	10.0 (2.2)	—	54	ActiGraph GT3X+	2 (hip, wrist)	ANN and DT	Lab	IC	On request
	Li et al [63]	4.0 (0.5)	—	34	ActiGraph GT3X-BT	1 (wrist)	k-meansp	Free-living	Hip cut points	No
	Mardini et al [64]	61.7 (17.7)	—	253	ActiGraph GT3X-BT	1 (wrist)	DT, RF, XGBoost, and LASSOq	Lab	IC	No
	Montoye et al [65]	22.0 (4.2)	—	40	ActiGraph GT3X+ and GENEActiv	4 (thigh, hip, both wrists)	ANN	Lab	PRE	No
	Montoye et al [66]	22.0 (4.2)	—	41	activPAL3	1 (thigh)	ANN	Lab	IC	No
	Montoye et al [67]	40.8 (19.2)	—	48	ActiGraph GT9X Link	2 (hip, wrist)	RF	Lab and free-living	DO	Yes
	Nawaratne et al [68]	45.0 (11.0)	—	119	ActiGraph GT3X +	1 (wrist)	CNNr	Free-living	Hip cut points	Yes
	Nnamoko et al [69]	69.3 (8.0)	—	33	GENEActiv and ActiGraph	2 (wrist, hip)	Additive regression tree	Lab	IC	No
	O'Driscoll et al [70]	44.4 (14.1); 31.9 (10.2)	—	89	ActiGraph GT3-X; SenseWear Armband	2 (wrist, upper arm)	RF, ANN, k-NN, SVM, and gradient boosting	Lab	IC	No
	Pober et al [71]	24.8 (4.2)	—	6	Actigraph MTI 7164	1 (hip)	QDAs and HMMt	Lab	PRE	No
	Skjødt et al [72]	80.2 (3.7)	—	67	ActiGraph GT3X +, GENEActiv, and Axivity AX3	6 (both hips, both wrists, thigh, lower back)	RF	Lab	IC	Yes
	Staudenmayer et al [73]	35 (0)	21-69	48	Actigraph model 7164	1 (wrist)	ANN	Lab	IC	No
	Staudenmayer et al [74]	24.1 (0)	20-39	20	ActiGraph GT3X+	1 (wrist)	RF and DT	Lab	IC	No
	Trost et al [19]	11 (2.7)	—	100	ActiGraph GT1M	1 (hip)	ANN	Lab	IC	No
	Trost et al [19]	11 (2.7)	—	100	ActiGraph GT1M	1 (hip)	ANN	Lab	IC	No
	Trost et al [28]	4.8 (0.9)	—	11	ActiGraph GT3X +	2 (hip, wrist)	RF and SVM	Lab	DO, IC	On request
	Tsanas [75]	—	18-91	148	Axivity AX3	1 (wrist)	RF and HMM	Free-living	DO	No
	Walmsley et al [76]	—	18-91	152	Axivity AX3	1 (wrist)	RF and HMM	Free-living	DO	No
	Wang et al [33]	—	18-91	151	Axivity AX3	1 (wrist)	ViT-BiLSTMu, CNN-BiLSTMv, ViTw, CNN, and BiLSTM	Free-living	DO	No
	Wullems et al [77]	73.5 (6.3)	—	40	GENEActiv	2 (both thighs)	RF	Lab	IC	No
	Wullems et al [78]	70.0 (12.0)	—	20	GENEActiv	1 (thigh)	RF	Lab	DO, IC	No
	Zhou et al [79]	5.0 (0.9)	—	24	Custom inertial measurement unit sensor	1 (arm)	BiLSTM	Lab and free-living	IC	No
Clinical conditions
	Bianchim et al [37]	12.0 (2.8)	—	35CF; 28hy	GENEActiv and ActiGraph	5 (both wrists, waist, both wrists)	k-NN, RF, and XGBoost	Lab	IC	No
	Cescon et al [80]	44.9 (5.0)	—	20T1Dz	Empatica E4 wristband	1 (wrist)	RF	Free-living	NR	No

^aMVPA: moderate-to-vigorous physical activity.

^bNot applicable.

^cRF: random forest.

^dSVM: support vector machine.

^eDO: direct observation.

^fPRE: predefined activity schedule.

^gIC: indirect calorimetry.

^hNR: not reported.

ⁱk-NN: k-nearest neighbor.

^jXGBoost: extreme gradient boosting.

^k1D-CNN-LSTM: one directional CNN-LSTM.

^lANN: artificial neural network.

^mDT: decision tree.

ⁿBiLSTM: bidirectional long short-term memory.

^oNB: naive Bayes.

^pk-means: k-means cluster analysis.

^qLASSO: least absolute shrinkage and selection operator.

^rCNN: convolutional neural network.

^sQDA: quadratic discriminant analysis.

^tHMM: hidden Markov model.

^uViT-BiLSTM: vision transformer bidirectional long short-term memory.

^vCNN-BiLSTM: convolutional neural network and bidirectional long short-term memory.

^wViT: vision transformer.

^x35^CF: 35 participants with cystic fibrosis.

^y28^h: 28 healthy participants in the study.

^z20^T1D: 20 participants with type 1 diabetes.