Table 4.

Characteristics of the included studies grouped within the 5 overall intervention domains: physical exercise, ergonomics, participatory ergonomics, multifaceted and stress management. Three interventional categories were further established within the domain of physical exercise: strength training, aerobic training, stretching. Four studies did not match any of the overall intervention domains and are presented as “Other” interventions. The characteristics include (1) author year and country, (2) study design, (3) study population, (4) intervention and comparison, (5) number of participants (n), (6) time-frames of outcome measurement (follow-up), (7) results (interventional effect and region of MSD), and (8) quality appraisal (H = high quality, M = medium quality)

Author, year, country	Study design	Study population	Intervention and comparison	n	Follow-up	Results (effect and region of MSD)	QA
Physical exercise
Strength training
Jakobsen (2015) Denmark [24]	RCT	Healthcare workers	I = High-intensity strength training and coaching	111	10 weeks	Yes (p ≤ 0.0003) Low back and neck/shoulder	H
			C = Control (home-based exercises)	89
Rasotto (2015) Italy [25]	RCT	Manufacturing workers	I = Mobilization and strength training	30	6 months	Yes (p = 0.039) Shoulder	H
			C = Control (no intervention)	30
Sundstrup (2014) Denmark [26]	RCT	Slaughterhouse workers	I = High-intensity strength training	33	10 weeks	Yes (p < 0.0001) Shoulder, arm and hand	H
			C = Control (individualized ergonomic training and education)	33
Zebis (2011)  Denmark [27]	RCT	Laboratory technicians	I = High-intensity strength training	282	20 weeks	Yes (p < 0.001, p = 0.07) Neck and shoulder	H
			C = Control (received advice to stay physically active)	255
Munoz-poblete (2019) Chile [28]	RCT	Manufacturing workers	I =  Strength training with progressive resistance	52	16 weeks	Yes (p = 0.007, p = 0.045, p = 0.259 p = 0.481, p = 0.016, p = 0.182, p = 0.034, p = 0.013) Upper limb, neck, right and left shoulders, right and left  elbows, right and left wrists	H
			C = Control (stretching exercise)	53
Jay (2011) Denmark [30]	RCT	Laboratory technicians	I = High-intensity strength training	20	8 weeks	Yes (p = 0.02, p = 0.05) Neck/shoulder, low back	M
			C = Control (received recommendation to continue their usual physical activities)	20
Rasotto (2015) Italy [32]	RCT	Metal workers	I = Mobilization and strength training	34	5 months	Yes (p = 0.0043, p = 0.1037, p = 0.2053, p = 0.0080) Neck, shoulder, elbow and wrist	M
					10 months	Yes (p = 0.0164, p = 0.0224, p = 0.3429, p = 0.0007) Neck, shoulder, elbow and wrist
			C = Control (continue in performing their normal daily activities)	34
Balaguier (2017) France [29]	Non-RCT	Vineyard workers	I = Morning: warm-up. After work: trunk flexor, extensor strengthening or/and  trunk stretching	10	4 weeks	No (p > 0.05) Low back	M
					8 weeks	Yes (p < 0.01) Low back
					12 weeks	Yes (p < 0.05) Low back
			C = Control (not further described)	7
Oldervoll (2001) Norway [31]	Non-RCT	Hospital employees	I:2 = Strength training	24	15 weeks	Yes (p = 0.031) Neck, shoulder, and lower back	M
			C = Control (continue their normal daily activities)	19
Aerobic training
Korshoj (2018) Denmark [33]	RCT	Cleaners	I = Aerobic exercise	57	4 months	No (p = 0.80) Low back	H
			C = Control (lectures on healthy living only)	59	12 months	No (p = 0.72) Low back
Barene (2014) Norway [34]	RCT	Hospital employees	I:2 = Soccer	37	12 weeks	Yes (p = 0.001) Neck and shoulder No (p > 0.05) Lower back region	H
					40 weeks	Yes (p = 0.002) Neck and shoulder No (p > 0.05) Lower back region
			C = Control (not further described)	35
Eriksen (2002) Norway [35]	RCT	Postal workers	I:3 = Physical aerobic  exercise	189	12 weeks	No (p = 0.517) Head, neck, upper back and low back, arm, shoulder, and leg	H
			C = Control (not further described)	344
Horneij (2001) Sweden [36]	RCT	Homecare workers	I:2 = Physical exercise (aerobic and stretching)	90	12 months	Yes (p = 0.02) Low back	H
			C = Control (usual care)	93
Oldervoll (2001) Norway [31]	Non-RCT	Hospital employees	I:1 = Aerobic exercise	22	15 weeks	Yes (p = 0.031) Neck, shoulder, and low back	M
			C = Control (continue their  normal  daily activities)	19
Stretching
Bertozzi (2015) Italy [37]	Non-RCT	Poultry slaughterhouse workers	I = Bodyweight and postural exercises, relaxation, stretching, and extension	20	5 weeks	No (p = 0.7, p = 0.1) Cervical and lumber	H
			C = Home exercise	20
Holmstrom (2005) Sweden [38]	Non-RCT	Construction workers	I = Morning warm-up including stretching exercises	37	3 months	No (p > 0.05) Back	M
			C = Control (not further described)	20
Han (2016) Korea [39]	Non-RCT	Automotive (assembly line)	I:1 = Pelvic control hamstring stretch	34	6 weeks	Yes (p < 0.05) Low back	M
			I:2 = General hamstring stretch	34	6 weeks	Yes (p < 0.05) Low back
			C = Control (home stretching)	32
General physical exercise
Andersen (2015) Denmark [40]	RCT	Healthcare workers	I = Aerobic fitness and strength training	27	3 months	Yes (p ≤ 0.01) All body parts/regions	H
			C = Control (received health guidance only)	27
Barene (2014) Norway [34]	RCT	Hospital employees	I:1 = Zumba	35	12 weeks	Yes (p = 0.01) Neck and shoulder	H
					40 weeks	No (p = 0.13) Neck and shoulder
			C = Control (not further described)	35
Gram (2012) Denmark [41]	RCT	Constructions workers	I = Aerobic exercise and strength training	35	12 weeks	No (p = 0.96, p = 0.11, p = 0.37, p = 0.31, p = 0.92, p = 0.73, p = 0.74, p = 0.70) Neck, shoulder: right, left and dominant, upper back, low back, hip, knee	H
			C = Control (given 1-hour lecture on general health promotion)	32
Jorgensen (2011) Denmark [42]	RCT	Cleaners	I:1 = Physical coordination training	95	12 months	No (p > 0.05) Neck, shoulder and low back	H
			C = Control (healthcare check, pulmonary test and aerobic capacity test)	100
Burger (2012) Switzerland [43]	Non-RCT	Manufacturing workers	I = Whole-body vibration training	22	4 weeks	Yes (p < 0.01) All body parts/regions	M
			C = Control (no treatment)	16
Ergonomics
Jensen (2006) Denmark [45]	RCT	Healthcare workers	I:1 = Ergonomics; practical class room education/instruction	61	3 months	No (p = 0.16) Low back	H
					12 months	No (p = 0.10) Low back
			C = Control (lessons on skincare, proper treatment of persons with diabetes, and asthma and safety procedures in chemicals handling)	49
Oleske (2007) USA [46]	RCT	Industrial workers (automotive)	I:1 = Back support + education	222	12 months	No (p = 0.091) Low back	H
			C = Control (education)	211
Roelofs (2007) Netherlands [47]	RCT	Healthcare workers	I = Lumbar support	183	12 months	Yes (p = 0.020) Low back	H
			C = Control (not further described)	177
Warming (2008) Denmark [49]	RCT	Nurses	I:1 = Ergonomics; transfer technique instruction, physical exercise	50	12 months	No (p > 0.05) Low back	H
			I:2 = Transfer technique instruction	55	12 months	No (p > 0.05) Low back
			C = Control (usual care)	76
Hagiwara (2017) Japan [50]	RCT	Healthcare workers	I = Lumbar support	59	3 months	Yes (p = 0.036) Knee, shoulder, neck, back	M
			C = Control (no intervention)	60
Yassi (2001) Canada [56]	RCT	Healthcare workers	I:1 = Safe lifting program	116	6 months	No (p > 0.05) Low back and shoulder	M
					12 months	Yes (p = 0.009, p = 0.041) Low back and shoulder
			I:2 = No strenuous lifting program	127	6 months	Yes (p = 0.015, p = 0.037) Low back and shoulder
					12 months	No (p > 0.05) Low back and shoulder
			C = Control (usual practice)	103
Shojaei (2017) Iran [48]	Non-RCT	Nurses	I = Educational program and ergonomic posture training	63	6 months	Yes (p < 0.001) Low back	H
			C = Control (no intervention)	62
Hartvigsen (2005) Denmark [44]	Non-RCT	Nurses	I = Educated in body mechanics, patient transfer, and lifting techniques, and use of low-tech ergonomic aids	171	24 months	No (p < 0.88) Low back	H
			C = Control (instruction in lifting technique)	145
Iwakiri (2018) Japan [51]	Non-RCT	Care workers	I = Ergonomic education program	49	12 months	No (p = 0.69) Low back	M
					18 months	No (p = 0.09) Low back
			C = Control (not further described)	33
Luijsterburg (2005) Netherlands [52]	Non-RCT	Construction  workers (bricklayer)	I = Devices for raised bricklaying	72	10 months	No (p = 0.65, p = 0.46, p = 0.95, p = 0.68, p = 0.68, p = 0.40) Low back, shoulder, hand-wrist	M
			C = Control (not further described)	130
Risor (2017) Denmark [53]	Non-RCT	Nurses	I = Patient handling equipment, buying relevant equipment, training in its use	293	12 months	No (p > 0.05) Low-back, neck, shoulders, knees, and wrists	M
			C = Control (not further described)	201
Sezgin (2018) Turkey [54]	Non-RCT	ICU nurses	I = An ergonomic risk management program based on the PRECEDE-PROCEED model	57	26 weeks	No (p = 0.633) All body parts/regions	M
			C = Control (not further described)	59
Shabat (2005) Israel [55]	Non-RCT	Postal workers	I = Insoles	41	5 weeks	Yes (p < 0.05) Low back	M
					10 weeks	Yes (p < 0.05) Low back
			C = Control (placebo insoles)	19
Participatory ergonomics
Brandt (2018) Denmark [57]	RCT	Construction workers	I = Participatory ergonomics: Reduce the number of events with excessive physical workload	32	3 months	No (p = 0.53) Arms, hands, knees, shoulder and back	H
					6 months	No (p = 0.59) Arms, hands, knees, shoulder and back
			C = Control (handouts about MSD and lifting guidelines)	48
Haukka (2008) Finland [58]	RCT	Kitchen workers	I = Participatory ergonomics: Identify strenuous work tasks and seek solutions for decreasing physical and mental workload	263	9–12 months	No (p > 0.05) 6 out of 7 body regions. Yes (p = 0.026) forearms/ hands	H
			C = Control (no visits and no trainings by researchers at these group)	241
Jakobsen (2019) Denmark [59]	RCT	Healthcare workers	I = Participatory ergonomics: Improve the use of assistive devices in patient transfer	316	6 months	No (p = 0.868, p = 0.205, p = 0.117) Low back, shoulder, neck	H
					12 months	No (p > 0.05) Low back, shoulder, neck
			C = Control (encouraged to continue with their normal working procedures including living up to standard OSH guidelines)	309
Morken (2002) Norway [61]	RCT	Industry workers	I:1 = Participatory ergonomics training program with  the operators and their supervisor	132	12 months	No (p > 0.05) All body parts/regions	M
			I:2 = Participatory ergonomics training program with operators only	135	12 months	No (p > 0.05) All body parts/regions
			I:3 = Participatory ergonomics training program with  managers and supervisors only	147	12 months	No (p > 0.05) All body parts/regions
			C1 = Control (not receive any special attention or information)	423
			C2 = Control (not receive any special attention or information)	1344
Laing (2005) Canada [60]	Non-RCT	Manufacturing workers	I = Participatory ergonomics: Ergonomics change team implementing physical changes at the factory	44	10 months	No (p = 0.33, p = 0.52, p = 0.33, p = 0.96, p = 0.26, p = 0.50, p = 0.62, p = 0.05) Back, shoulder/upper arm forearm/hand and leg/lower limb	M
			C = Control (not further described)	39
Multifaceted
Chaleat-Valayer (2016) France [62]	RCT	Healthcare workers	I = Pain management education, exercise at workplace, exercise at home; booklet for self-management	171	18 months	No (p = 0.1417, p = 0.7002) Lumbar and radicular	H
			C = Control (usual care)	171
Christensen (2011) Denmark [63]	RCT	Healthcare workers	I = Exercise; strength training, CBT, dietary	54	12 months	No (p = 0.452, p = 0.427, p = 0.476, p = 0.552) Neck, shoulder, upper back, lower back	H
			C = Control (a monthly two-hour oral lecture)	44
Eriksen (2002) Norway [35]	RCT	Postal workers	I:2 = Exercise, information on stress, coping and practical examination (IHP)	165	12 weeks	No (p = 0.517) Head, neck, upper back and low back, arm, shoulder, and leg	H
			I:4 = Organizational intervention	199	12 weeks	No (p = 0.517) Head, neck, upper back and low back, arm, shoulder, and leg
			C = Control (not further described)	344
Ijzelenberg (2007) Netherlands [64]	RCT	Physical demanding workers (not specified)	I = Individually tailored education and training, immediate treatment of sub-acute LBP, ergonomic adjustment	258	12 months	No (p > 0.05) Low back, upper extremity	H
			C = Control (usual care)	231
Jaromi (2018) Hungary [65]	RCT	Nurses	I = Back school program: Didactic education, spine-strengthening exercises and education in patient handling techniques	67	12 weeks	Yes (p < 0.001) Low back	H
			C = control (written lifestyle guidance)	70
Jay (2015) Denmark [66]	RCT	Laboratory technicians	I = Physical, cognitive, and mindfulness group-based training	56	10 weeks	Yes (p < 0.0001) Neck, back, shoulder, elbow and hand	H
			C = Control (encouragement to participate in the company’s on-going health initiatives)	56
Oude Hengel (2013) Netherlands [68]	RCT	Construction workers	I = Ergonomics, rest break, empowerment	171	3 months	No (p-value NA) Back, neck, shoulder, upper extremities, lower extremities	H
					6 months	No (p-value NA) Back, neck, shoulder, upper extremities, lower extremities
					12 months	No (p-value NA) Back, neck, shoulder, upper extremities, lower extremities
			C = Control (not further described)	122
Peters (2018) USA [69]	RCT	Construction workers	I = Ergonomics + worksite health promotion	324	1 month	No (p = 0.252) All body parts/regions	H
					6 months	No (p = 0.683) All body parts/regions
			C = Control (no intervention)	283
Rasmussen (2015) Denmark [70]	RCT	Nurses	I = Participatory ergonomics, physical training, CBT (cross-over design)	594	12 weeks	Yes (p =  < 0.0001) Low back	H
Roussel (2015) Belgium [71]	RCT	Hospital employees	I = Exercise, nutritional and psychological intervention, ergonomics	31	6 months	No (p > 0.05) Low back	H
			C = Control (not further described)	38
Viester (2015) Netherlands [72]	RCT	Construction workers	I = Intervention mapping and coaching program	162	6 months	No (p > 0.05) Back, neck/shoulders, upper extremities, and lower extremities	H
					12 months	No (p > 0.05) Back, neck/shoulders, upper extremities and lower extremities
			C = Control (usual care)	152
Warming (2008) Denmark [49]	RCT	Nurses	I1 = Ergonomic; transfer technique instruction, physical exercise	50	12 months	No (p > 0.05) Low back	H
			C = Control (usual care)	76
Tveito (2009) Norway [74]	RCT	Nurses	I = Exercise, ergonomic	19	9 months	No (p = 0.283, p = 0.220) Neck, back	M
			C = Control (no intervention)	21
Kamioka (2011) Japan [67]	Non-RCT	Caregivers	I = Stretching exercise + ergonomic: learning	44	12 weeks	No (p = 0.653) Low back	H
			C = Control (not further described)	44
Szeto (2010) Hong Kong [73]	Non-RCT	Nurses	I = Ergonomics training, exercise, education/theory (back school program)	14	8 weeks	No (p = 0.067) Shoulder, low back, neck, knee, elbow	M
			C = Control (no intervention)	12
Stress management
Eriksen (2002) Norway [35]	RCT	Postal workers	I:1 = Stress management training	162	12 weeks	No (p = 0.517) Head, neck, upper and lower back, arm, shoulder, and leg	H
			C = Control (not further described)	344
Horneij (2001) Sweden [36]	RCT	Homecare workers	I:1 = Stress management	93	12 months	No (p = 0.057) Low back	H
					18 months	No (p = 0.063) Low back
			C = Control (usual care)	99
Jensen (2006) Denmark [45]	RCT	Healthcare workers	I:2 = Stress management	53	3 months	No (p = 0.64) Low back	H
					12 months	No (p = 0.85) Low back
			C = Control (lessons on skincare, proper treatment of persons with diabetes, and asthma and safety procedures in chemicals handling)	49
Others
Jorgensen (2011) Denmark [42]	RCT	Cleaners	I:2 =  CBT	99	12 months	No (p > 0.05) Neck, shoulder and low back	H
			C = Control (health care check, pulmonary test and aerobic capacity test)	100
Sundstrup (2014) Denmark [77]	RCT	Slaughterhouses workers	I = Topical menthol	5	48 hours	Yes (p = 0.016, p = 0.027) Hand, forearm, elbow, wrist, arm	H
			C = Control (placebo gel)	5
Faucett (2007) USA [75]	Non-RCT	Agriculture workers	I:1 = Rest breaks trial 1	30	3 days	Yes (p = 0.01) Mid/lower back and lower extremities	M
			I:2 = Rest breaks trial 2	16	3 days	Yes (p = 0.01) Mid/lower back and lower extremities
			C = Control (only legally breaks)	36
Wergeland (2003) Norway [76]	Non-RCT	Care institution workers	I = Reduced working hours	147	12 months	Yes (p = 0.034) Neck/shoulder.         No (p = 0.320) Back	M
			C = Control (not further described)	286

QA quality appraisal, H high quality study (> 85% of criteria met) and M medium quality study (50–85% of criteria met), CBT cognitive-behavioural therapy, RCT randomized controlled trial, non-RCT non-randomized controlled trial, I intervention group (if multiple intervention arms are present, I 2 refers to intervention arm number 2 etc.), C control/comparison group