Arampatzis 2017.

Study characteristics
Methods	Study design: RCT Setting: Germany, general population Exercise groups: 1 Comparison groups: 1
Participants	Number of participants: 45 (E1 = 24, C1 = 21) Chronic LBP duration: Not specified (not specified) Neurological/radicular symptoms: No participants Mean age (years): 32 Sex (female): 42%
Interventions	Exercise Group 1 (E1): Seventy‐minute abdominal perturbation training as stabilisation exercises with 10 minutes whole body exercises and 10 minutes cool down exercises; type = core strengthening; duration = 13 weeks; dose = high; design = partially individualised; delivery = individual; additional intervention = none Comparison Group 1 (C1): Usual care/no treatment (control group: no intervention)
Outcomes	Core outcomes reported: Pain (Visual Analogue Scale); function (Low Back Pain Rating Scale) Follow‐up time periods available for syntheses: 13 weeks (moderate)
Notes	Conflicts of interest: None to declare Funding source: German Federal Institute of Sport Science; MiSpEx National Research Network for Medicine in Spine Exercise (Grant Number 080102A/11‐14) Other: Information modified for author contact
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Block random‐number procedure
Allocation concealment (selection bias)	Low risk	Treatment allocation was likely concealed; the randomisation procedure was controlled by a member of the same institution, who was not involved in the design and execution of the study.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	1. Patients could not be blinded to allocation due to the nature of the treatments; 2. Exercise therapy required machinery that would not be accessible outside of study context.
Blinding of care provider (performance bias)	Low risk	1. Care providers could not be blinded to allocation due to the nature of the treatments; 2. Therapists seemed to have had minimal contact with control group; exercise therapy so distinct and specific that no deviation could casually occur.
Blinding of outcome assessment (detection bias) All outcomes	High risk	1. Outcome assessors in this study were the patients themselves, who could not be blinded due to the nature of the treatments; 2. Pain and functional questionnaires are subjective, and responses could be altered by awareness of intervention; 3. Likely that lack of patient blinding led to perception that experimental group was better than control, and so biased the outcome assessments accordingly; pain study results supported this.
Incomplete outcome data (attrition bias) All outcomes	Low risk	1. 5 patients of 45 did not finish the study, 11%.
Participants analysed in group allocated (attrition bias)	Low risk	1. Appeared that all patients were analysed according to the treatment group to which they were randomised
Selective reporting (reporting bias)	Low risk	1. No linked protocol or statistical analysis plan found: within this paper all outcomes and analyses fully reported, functional status not measured, but isometric measurements likely took place.
Groups similar at baseline (selection bias)	Low risk	Both treatment groups were similar at baseline on age, sex, pain, height and weight, but there was no reporting of duration of symptoms.
Co‐interventions avoided or similar (performance bias)	Low risk	Co‐interventions were largely avoided, as the study excluded patients with continuous dependency on pain relief medication or physiotherapist treatment.
Compliance acceptable in all groups (performance bias)	Low risk	No information on compliance/adherence/attendance to sessions was reported.
Timing of outcome assessment similar in all groups (detection bias)	Low risk	1. All outcome assessments were identical, regardless of treatment group; 2. Visual Analogue Scale (for pain) is a well‐validated tool in the low back pain context.
Other bias	Low risk	Appeared free from other sources of bias