Hagberg 2000.

Methods	RCT; concealed randomisation, multi‐centre trial; n = 3
Participants	Woman industrial workers seeking medical attention for neck or shoulder pain. Chronic (three‐month) neck/shoulder complaints (non‐specific; n = 77). Industrial workers with gradual onset of symptoms during work
Interventions	Endurance training: isometric shoulder endurance training; n = 43 Strength training: isometric shoulder strength training; n = 34   Training once a week supervised by physiotherapist for 12 weeks. Follow‐up at 24 weeks
Outcomes	Pain (VAS), ROM, sick leave, strength (dynamometer), endurance (RPE)
Notes	No data available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Allocation by chance (dice)
Allocation concealment (selection bias)	Low risk	Principal investigator blinded for allocation
Blinding of participants?	Unclear risk	Unclear whether participant is blinded
Blinding of caregivers?	High risk	Not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome assessment not blinded
Incomplete outcome data (attrition bias) All outcomes ‐ <20% drop‐outs?	Low risk	Eight dropouts, reasons given, < 20%
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis performed?	High risk	No ITT analysis
Selective reporting (reporting bias)	Unclear risk	No protocol
Similarity of baseline characteristics?	Low risk	Groups similar at baseline
Co‐interventions avoided?	Unclear risk	Unclear whether co‐interventions were avoided
Compliance acceptable ?	Unclear risk	Unclear compliance rate
Timing outcome assessment comparable?	Low risk	Timing comparable