Longo 2016.

Study characteristics
Methods	Study design: RCT Setting: Italy, healthcare Exercise groups: 1 Comparison groups: 1
Participants	Number of participants: 14 (E1 = 7, C1 = 7) Chronic LBP duration: 14.58 months (moderate) Neurological/radicular symptoms: Some participants Mean age (years): 52 Sex (female): 57%
Interventions	Exercise Group 1 (E1): Posture called "standing posture with flexion of the trunk" in addition to physiotherapy: position maintained from 30 to 60 seconds and was repeated 5 times, with a one‐minute break between repetitions; type = core strengthening & stretching; duration = 4 weeks; dose = low; design = standardised; delivery = group; additional intervention = none Comparison Group 1 (C1): Other conservative treatment (physical therapy)
Outcomes	Core outcomes reported: Pain (Numerical Rating Scale); function (Roland‐Morris Disability Questionnaire) Follow‐up time periods available for syntheses: 4 weeks (short)
Notes	Conflicts of interest: None to declare Funding source: Not reported Other: Information modified for author contact
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation not described beyond the fact that patients were "randomly divided" into treatment groups
Allocation concealment (selection bias)	High risk	Not described beyond the fact that patients were "randomly divided" into treatment groups
Blinding of participants and personnel (performance bias) All outcomes	Low risk	1. Unlikely that the patients could be blinded as to whether or not they received an extra exercise at the end of their physiotherapy routines; 2. Unlikely that a lack of patient blinding led to deviations from the intended intervention because the difference between treatment groups was only a single exercise, and it required physiotherapy guidance
Blinding of care provider (performance bias)	Unclear risk	1. Care providers (physiotherapist) could not be blinded to intervention because they delivered it, and had to know whether or not to deliver the exercise of interest; 2. Very possible that lack of physiotherapy blinding led to deviations from intervention because the article explicitly stated that physiotherapists could use their discretion and did not use a strict protocol; 3. Likely that any deviations from intended intervention due to lack of physiotherapist blinding were balanced between groups because both groups received the same unstructured physio treatment
Blinding of outcome assessment (detection bias) All outcomes	High risk	1. Since the outcome assessors for pain and disability were the patients, it is unlikely they were blinded to the intervention allocation; 2. Pain and functional questionnaires are subjective, and responses could be altered by awareness of intervention; 3. One group was getting "conventional" care while the other was getting something supplemental; could alter assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	1. No dropouts from baseline to time point 1; there were dropouts at time point 2, but these outcome data were incomplete and not extracted for systematic review.
Participants analysed in group allocated (attrition bias)	Low risk	1. Appeared that all patients were analysed according to their assigned treatment group, according to intention‐to‐treat analysis
Selective reporting (reporting bias)	Low risk	1. No linked protocol found: no obvious omissions in outcomes or analyses
Groups similar at baseline (selection bias)	Low risk	No statistically significant between‐group differences in baseline age, sex, body mass index, symptom duration, pain or disability; nearly clinically significant difference in body mass index and disability: worse in control
Co‐interventions avoided or similar (performance bias)	Low risk	Care providers were not given any strict protocols (especially around co‐interventions) to follow in their "usual care", but they could have applied this equally to both treatment groups.
Compliance acceptable in all groups (performance bias)	High risk	Compliance (attendance) was not reported in the study, and so not able to determine exact compliance
Timing of outcome assessment similar in all groups (detection bias)	Low risk	1. All outcome assessments were carried out with the same tools and at the same time for both treatment groups, up until T1 assessments; only experimental followed to T2; 2. Numeric Rating Scale (for pain) and Roland‐Morris Disability Questionnaire (for disability) are validated tools in low back pain context.
Other bias	Low risk	Appeared free from other sources of bias