Hides 2001.

Methods	Randomised, controlled, concealed allocation, and single‐blinded (outcome assessor).
Participants	Patients with acute, first‐episode LBP. For this study, total of 39 participants were accepted. 16 men and 23 women, mean age 31 years. Intervention group, N = 20; Control group, N = 19; Inclusion criteria: participants of both genders, age 18 to 45 years, first episode of LBP for less than 3 weeks, presented to the accident and emergency department. Exculsion criteria: provided elsewhere.
Interventions	Exercise group: Subjects performed specific localized exercises aimed at restoring the stabilizing protective function of the multifidus, twice a week for 4 weeks. Usual care group: Subjects received medical management, including advice on bed rest, absence from work, prescription of medication, and advice to resume normal activity as tolerated.
Outcomes	Number of subjects with recurrent LBP, number of recurrences of LBP, and number of subjects with sick leave due to LBP.
Notes	This is a follow‐up study. The original study is not included in the review. It is possible that the N participants in the original study was greater than N=39 identified for the follow‐up.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk
Allocation concealment?	Low risk	Adequate.
Blinding? All outcomes	High risk	Patient's and Providers not blinded; Outcome assessor blinded: 'research assistant who was blinded to group allocation'.
Incomplete outcome data addressed? All outcomes ‐ drop‐outs?	Low risk
Incomplete outcome data addressed? All outcomes ‐ ITT analysis?	Low risk	Outcomes for patients lost to follow‐up imputed.
Similarity of baseline characteristics?	Low risk
Co‐interventions avoided or similar?	Low risk
Compliance acceptable?	Low risk
Timing of outcome assessments similar?	Low risk