Results
LBP, Pain
RECRUITMENT
Recruitment took place in different primary care centers of the “Institut Català de la Salut” in Lleida (Spain) from April to August 2017. Of 271 potential subjects, 155 were impossible to contact, and 78 were excluded after the telephone interview. Figure 
CONSORT Flow diagram of the studyFinally, 38 patients participated in the study (see Table The initial analysis of the groups showed no significant difference in the quantitative demographic characteristics, such as age, BMI, or the onset of the first episode of LBP. For the qualitative variable sex, it was found that in the control group, 61% were men compared to 39% women, while in the intervention group, the percentage of men was only 29%, but this difference was not significant according to Pearson’s chi-square test (p = 0.23) (Table 
Baseline Characteristic of participantsNotes: Values are presented as mean (standard deviation)Abbreviations: W women; M Men; LBP Low Back Pain; TrA; abdominal transversus muscle; RMQ Roland-Morris Questionnaire; PBU Pressure Biofeedback Unit; US Ultrasound; CSA: cross-sectional area