Table 1.

Characteristics of included studies.

Study (year)	Written language	Type of study	Participants description (M ± SD)		Intervention form and intensity of the OEP	Duration	Measurement methods
			EG (N = 269)	CG (N = 277)
Kocic et al (2018)[17]	English	RCT	N = 27 Age = 77.5 ± 6.9	N = 33 Age = 78.7 ± 7.3	Part one: ≥40 min/3 d/wk, Part two: 30 min/≥2 d/wk	3 mo	BBS TUG
Wang et al (2019)[18]	Chinese	Non-RCT	N = 35 Age = 85.0 ± 3.0	N = 41 Age = 84.6 ± 6.0	Part one: 40–60 min/≥2 d/wk Part two: 30 min/≥2 d/wk	3 mo	TUG 30s-CST Number of frail elders
Cheng et al (2020)[19]	Chinese	Non-RCT	N = 10 Age = 84.7 ± 4.7	N = 10 Age = 81.4 ± 4.3	Part one + two: 45 min/3 d/wk	6 mo	30s-CST
Jahanpeyma et al (2020)[20]	English	RCT	N = 35 Age = 74.6 ± 5.9	N = 36 Age = 75.8 ± 4.5	Part one: 45 min/3 d/wk Part two: 30 min/3 d/wk	3 mo	BBS 6MWT 30s-CST Number of falls
Chen et al (2021)[21]	English	RCT	N = 29 Age = 84.6 ± 4.2	N = 30 Age = 84.8 ± 5.4	Part one: 30 min/3 d/wk	3 mo	BBS TUG
Knott et al (2021)[22]	English	Non-RCT	N = 30 Age = 87.3 ± 7.0	N = 29 Age = 87.6 ± 5.2	Part one + two: 30–45 min/2–3 d/wk	1 y	Number of falls
García-Gollarte et al (2021) [23]	English	RCT	N = 39 Age = 86.0 ± 5.9	N = 34 Age = 87.3 ± 5.3	Part one + two: 45–60 min/3 d/wk	6 mo	BBS TUG 6MWT
Zou et al (2022)[24]	English	Non-RCT	N = 29 Age = 85.2 ± 3.1	N = 28 Age = 85.8 ± 5.1	Part one: 40–60 min/≥2 d/wk Part two: 30 min/≥2 d/wk	3 mo	TUG 30s-CST
Sahin et al (2022)[25]	English	RCT	N = 35 Age = 74.6 ± 5.9	N = 36 Age = 75.8 ± 4.5	Part one: 45 min/3 d/wk Part two: 30 min/3 d/wk	3 mo	Number of frail elders

30s-CST = 30-second Chair Stand Test, 6MWT = 6-minute walking test, BBS = Berg Balance Scale, CG = control group, EG = experimental group, M = mean, N = number of participants, RCT = randomized controlled trial, SD = standard deviation, TUG = Timed Up and Go test.