INTRODUCTION: Locomotion training is a simple exercise program that includes basic movements including squats and single-leg standing, with options to add exercises like heel raises and forward lunges according to the patients’ activity level. It is designed to improve lower extremity muscle strength; therefore, its effects on body balance enhancement and fall prevention have been well-documented. However, its impact on spinal health, particularly on paraspinal muscles, remains unclear. This study aimed to clarify the effect of locomotion training on fat infiltration and mass volume of paraspinal muscles in patients with locomotive syndrome over a 2-year prospective follow-up.
METHODS: We included 66 outpatients (age, 76.4 ± 6.4 years; 8 men, 58 women) with locomotive syndrome risk level 1 or higher who received treatment at our clinic between 2016 and 2019. Patients who completed a 24-month program of weekly supervised locomotion training-based rehabilitation (20 minutes of exercise and stretching) were defined as the intervention group (n = 33), while those who performed only home exercise with routine evaluations were defined as the observation group (n = 33). Standing whole-spine radiographs were obtained at baseline and after 2 years to assess the sagittal vertical axis (SVA) and the presence of vertebral fractures. Lumbar spine MRI was also performed at baseline and after 2 years, and the cross-sectional area (CSA) and fat infiltration rate (FIR) for each paraspinal muscle component of multifidus, erector spinae, and psoas major were measured at the L4/5 intervertebral disc level bilaterally. The locomotive syndrome risk level and Oswestry Disability Index (ODI) scores were recorded to assess baseline and post-2-year changes.
RESULTS: Baseline characteristics showed a higher locomotive syndrome risk level in the intervention group (p=0.01). The intervention group showed a significant improvement in the FIR of multifidus and erector spinae (multifidus: 47.4%→42.8%, p < 0.01; erector spinae: 28.8%→25.3%, p < 0.01), while these measures significantly worsened in the observation group (multifidus: 45.2%→48.1%, p < 0.01; erector spinae: 24.7%→28.4%, p < 0.01). The CSA of psoas major increased significantly in the intervention group (737.3 mm²→764.2 mm², p < 0.01), with a significant negative correlation between changes in the CSA and SVA (r = −0.56, p < 0.01). Bone mineral density (BMD) tended to be maintained in the intervention group; however, the difference was not statistically significant (intervention group: 0.480→0.477 g/cm², p = 0.37; observation group: 0.482→0.469 g/cm², p = 0.12). The incidence of new vertebral fractures (grade ≥ 2) also showed no difference between the groups (3.3% vs. 3.3%, p > 0.99). Additionally, improvements in the locomotive syndrome risk level (2.8→2.0; p < 0.01) and ODI (22.0%→15.4%; p < 0.01) were observed in the intervention group.
DISCUSSION: Sustained locomotion training for patients with locomotive syndrome resulted in the reduced FIR of multifidus and erector spinae muscles and the increased muscle mass of psoas major. Enhanced trunk muscle strength could help improve degenerative postural abnormalities (positive SVA progression), potentially leading to better maintenance and improvement of locomotive syndrome risk levels, ODI scores, and activities of daily living.