Outcome measures
Anxiety, Pain, Isometric muscular endurance, pain, Depression, disability
SECONDARY, CONTRACTION, DECUBITUS
The co-primary outcomes will be pain intensity and disability at 8 weeks (post-treatment). Pain intensity was measured using the 11-point Pain NRS, a numerical scale where 0 indicates no pain and 10 indicates maximum pain intensity, presenting good levels of test–retest reliability intraclass correlation coefficient (ICC = 0.94) [The secondary outcomes will be as follows:Pain intensity at 16 weeks follow-up;Disability at 16 weeks follow-up;Health-related quality of life at all time points: measured with the WHOQOL-Pain [Self-efficacy at all time points: measured with the Chronic Pain Self-Efficacy Scale [Depression, Anxiety, and Stress at all time points: measured by the Depression Anxiety Stress Scale [Sleep quality at all time points: measured by the Pittsburgh Sleep Quality Index [Work ability at all time points: measured by a single-item question, “Are you working at a physically less demanding job now because of your back and/or leg pain?” [Isometric muscular endurance of the trunk extensor at 8 weeks (post-treatment): measured by the modified Biering-Sorensen test [Isometric muscular endurance of the trunk flexors at 8 weeks (post-treatment): measured by a test that consists of remaining in isometry as long as possible in a sitting position with 45° hip flexion [Maximum isometric strength of the trunk extensor and flexor muscles at 8 weeks (post-treatment): maximum voluntary isometric contraction (MVIC) was measured by a calibrated load cell (Miotec®, Porto Alegre, Brasil) of 200 kgf. For the MVIC test of the trunk flexors muscles, the participants were positioned in a sitting position on top of the stretcher, with knees extended, legs fixed to the stretcher with two traction straps, hips flexed and resting on the backrest of the stretcher adjusted at 30° the surface of the stretcher, and arms crossed in front of the torso. For the MVIC test of the trunk extensor muscles, the participants were positioned in ventral decubitus, with knees extended and legs fixed to the stretcher with traction straps and elbows flexed with hands superimposed on the head. For both tests, the load cell was attached to an adapted stretcher, aligned perpendicularly to the torso, passing through the stretcher’s aperture. Chains connected the load cell to a traction belt positioned at rib height (xiphoid process). Participants performed three 5-s attempts for each position, with a 2-min interval between each attempt. During the tests, participants were verbally encouraged to apply maximum force as quickly as possible. The cell load values (kgf) were transformed into Newton (N) and multiplied by the distance (m) between the hip joint (greater trochanter of the femur) and the point of attachment of the traction belt to calculate peak torque in N.m;Muscular activation of spine flexor and extensor muscles at 8 weeks (post-treatment): simultaneously with the MVIC collection, the neuromuscular activation of the trunk flexor (rectus abdominis) and extensors (erector spinae—longissimus) muscles was measured using the surface electromyography technique (sEMG). A Miotool device (Miotec®, Porto Alegre, Brazil) was used with 1 cm Ag/AgCl electrodes (Meditrace®, Mansfield, Canada) and an interelectrode distance of 30 mm. The sEMG signal was collected from the right side of the participant’s body. During the assessments, the recommendations of skin preparation, asepsis, and fixation of the SENIAM electrodes were observed [Occupational performance at 8 weeks (post-treatment): measured by a task that simulates a victim rescue. The participant will drag a dummy (weight = 60 kg) away from the start line, around a cone placed at the 13 m mark, and return to the start line. The longer the time indicates worse occupational performance.Eligible participants were randomly allocated to the intervention or control group with a 1:1 simple allocation using a computer-generated randomization sequence created by a blinded investigator via a random function in Excel software for Windows. After randomization, an independent researcher emailed each participant the login and password to access the specific app version to which they were allocated (intervention or control). Afterward, an assistant researcher inserted them into numbered, sealed, and opaque envelopes.