1. Investigación

Unstable shoe was developed as a walking device to strengthen the lower extremity muscles and reduce joint loading. A large number of studies have reported in asymptomatic adults increased electromyography (EMG) activity throughout the gait cycle in most of the lower limb muscles. However, no previous studies have explored the effects of wearing unstable shoes on trunk muscle activity in patients with chronic low back pain (CLBP). Therefore, the aim of the present study was to compare trunk muscle activity during gait using an unstable shoe and a conventional flat control shoe in patients with CLBP. Thirty-five CLBP patients (51.1±12.4 yrs.; 26±3.8 kg/m2; 9.3±5.2 Roland Morris Disability Questionnaire score) were recruited from the Orthopedic Surgery Service at the Hospital to participate in this cross-sectional study. All participants underwent gait analysis by simultaneously collecting surface electromyography (EMG) data from erector spinae (ES), rectus abdominis (RA), obliquus internus (OI) and obliquus externus (OE) muscles, while walking on a treadmill with flat control shoes and experimental unstable shoes. The results showed significantly higher %EMG activity in ES (mean difference: 1.8%; 95% confidence interval [CI] 1.3 to 2.2), RA (mean difference: 1.5%; 95% CI 0.3 to 2.7), and OI (mean difference: 1.5%; 95% CI 0.2 to 2.8) in the unstable shoes condition compared to the flat shoes condition. Based on these findings, the use of unstable shoes may have potential implications in promoting spine stability, particularly in improving neuromuscular control of trunk muscles in CLBP treatment.

Objective: To investigate the effects that wearing unstable shoes has on disability, trunk muscle activity, and lumbar spine range of motion (ROM) in patients with chronic lower back pain (CLBP). Design: Randomized controlled trial. Setting: Orthopedic Surgery Service. Participants: We randomized 40 adults with nonspecific CLBP either to an unstable shoes group (n = 20) or to the control group (n = 20). Intervention: The participants in the unstable shoes group were advised to wear these shoes for a minimum of six hours a day for four weeks. Control group participants were asked to continue wearing their regular shoes. Outcome measures: Our primary outcome was measurement of back-related dysfunction, assessed using the Roland-Morris Disability Questionnaire. Secondary outcomes included changes in electromyographic (EMG) activity of erector spinae (ES), rectus abdominis (RA), internus obliquus (IO), and externus obliquus (EO) muscles, and changes in lumbar spine ROM. Results: Between-group analysis highlighted a significant decrease in disability in the unstable shoes group compared to the control (−5, 95% confidence interval (CI) = −8.4 to −1.6). Our results revealed a significant increase in the percentage of RA, ES, IO, and EO EMG activity and in lumbar spine ROM in the unstable shoes group compared to the control group. Moreover, our results showed a significant negative correlation between disability and the percentage of ES, RA, and IO muscle activity at the end of the intervention.