Erhard 1994.

Study characteristics
Methods	Study design: RCT Recruitment period: not reported, duration 6 months Recruitment mode: people referred to physical therapy Statistical analysis: 2 × 3 (treatment group treatment period) ANOVA with treatment group as a between‐group factor and treatment period as a within‐group factor Sample size calculation: not reported
Participants	Sample size: total: 24; EG1: 12; EG2: 12 Setting: 5 outpatient clinics that treated primarily orthopaedic disorders Country: USA Baseline characteristics Age in years, mean (SD): EG1: 41 (15); EG2: 47 (15) Sex, number (%) women: EG1: 5 (42%); EG2: 4 (33%) Duration LBP: in days, mean (SD): EG1: 22 (17); EG2: 20 (23) Inclusion criteria LBP syndrome Classification into extension/mobilisation group Exclusion criteria All other patients
Interventions	EG1: extension group Description: an extension‐oriented treatment regimen as proposed by McKenzie, including press‐ups, the use of a lumbar roll, and postural instruction. The use of flexed postures was discouraged, and a handout with illustrations of extension exercises was provided. Materials/equipment: lumbar roll Non‐exercise component: none Frequency and duration: 3 times per week. Every effort was made to have the third visit within a 7‐day window from the initial visit. No third visit occurred greater than 9 days from the initial visit. Delivery: partially independent: individually supervised session and unsupervised home programme component; generic or individual tailored not reported Provider: PT EG2: manipulation/hand‐heel rock group Description: manipulation procedure purported to affect the sacroiliac joint. Immediately following the manipulation, participants were instructed in hand‐heel rocking. On follow‐up visits, the manipulation hand‐heel rock group was reassessed, and if 3 or more of the signs were present, a second manipulation was administered. No postural instruction was afforded, nor were any props used other than a handout illustrating the exercise. Materials/equipment: no Non‐exercise component: manipulation Frequency and duration: 3 times per week. Every effort was made to have the third visit within a 7‐day window from the initial visit. No third visit occurred greater than 9 days from the initial visit. Delivery: partially independent: individually supervised session and unsupervised home programme component; generic or individual tailored not reported Provider: PT
Outcomes	Note: outcomes were not designated as minor or minor outcomes. Functional status: ODI Baseline, mean (SD): EG1: 40.0 (14.0); EG2: 48.0 (8.0) 4 weeks, mean (SD): EG1: 22.2 (14.5); EG2: 0.7 (1.6) Adverse events: not reported
Notes	Authors' results and conclusions: a manipulative procedure followed by an exercise program that includes both flexion and extension results in a more rapid resolution of symptoms and improvement in functional limitations than an established extension program alone. Funding: no funding sources reported Declaration of interest: no conflicts of interest reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Flip of a coin.
Allocation concealment (selection bias)	High risk	Not described, only the use of flipping a coin.
Blinding All outcomes ‐ Participants	High risk	No attempts made to blind participants.
Blinding All outcomes ‐ Healthcare providers	High risk	No attempts made to blind healthcare providers.
Blinding All outcomes ‐ outcome assessors	High risk	The outcome measures were self‐reported and participants were unblinded.
Influence of co‐interventions	Unclear risk	Not stated.
Group similarity at baseline	Low risk	Only slight differences.
Compliance	Unclear risk	Not stated.
Timing of outcome assessments	Low risk	3 days, 5 days, 1 month.
Incomplete outcome data (attrition bias) Dropouts – all outcomes	High risk	12 participants lost to follow‐up at 1 month (50% in each group).
Intention‐to‐treat‐analysis	Low risk	Many dropouts.
Selective reporting (reporting bias)	High risk	Study reported functional status but not pain. No published protocol.
Other bias	Unclear risk	No funding sources reported. No official disclosure regarding potential conflicts of interest.