Sjögren 2005.

Methods	RCT; cluster‐randomised, cross‐over trial; four clusters
Participants	Office workers with headache, neck or shoulder pain; n = 53
Interventions	I: Physical exercise: progressive light resistance training and guidance; n = 36 C: No intervention: n = 17   Treatment period: 15 weeks; cross‐over at 15 weeks
Outcomes	Pain (Borg CR10 Scale), strength
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Cluster‐randomisation, but method of randomisation not specified
Allocation concealment (selection bias)	Low risk	"Blind measurers allocated the workers into the two treatment sequences"
Blinding of participants?	High risk	Participants not blinded
Blinding of caregivers?	Unclear risk	Unclear
Blinding of outcome assessment (detection bias) All outcomes	High risk	Self‐reported outcomes used and participants not blinded
Incomplete outcome data (attrition bias) All outcomes ‐ <20% drop‐outs?	Low risk	Two participants lost to follow‐up: < 20%
Incomplete outcome data (attrition bias) All outcomes ‐ ITT analysis performed?	Low risk	Figure 1: main analysis intention‐to‐treat, none excluded from analysis
Selective reporting (reporting bias)	Unclear risk	No protocol
Similarity of baseline characteristics?	Low risk	Baseline comparable: see Table 1
Co‐interventions avoided?	Low risk	"Other physical activity performed outside the intervention was controlled by a structured interview"
Compliance acceptable ?	Low risk	Compliance: Participants maintained a weekly diary: 78% to 68%
Timing outcome assessment comparable?	Low risk	Timing was comparable