Effects of unstable shoes on trunk muscle activity in patients with chronic low back pain

Abstract

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.