Different Properties of the Erector Spinae and Multifidus Muscles on Physical Performance in Patients With Chronic Obstructive Pulmonary Disease

Kyosuke Imashiro,1,2 Masanori Nakanishi,3 Yuta Minoshima,1,2 Ken Kouda,2 Seigo Sasaki,4 Koichiro Takahashi,5 Kazuhisa Asai,6 Tsunahiko Hirano,7 Kazuto Matsunaga,7 Yoshiaki Minakata4 1Division of Rehabilitation, Wakayama Medical University Hospital, Wakayama, 641-8510, Japan; 2Department of Rehabilitation Medicine, Wakayama Medical University, Wakayama, 641-8509, Japan; 3Third Department of Internal Medicine, Wakayama Medical University, Wakayama, 641-8509, Japan; 4Department of Respiratory Medicine, NHO Wakayama Hospital, Hidaka-Gun, Wakayama, 644-0044, Japan; 5Division of Hematology, Respiratory Medicine and Oncology, Department of Internal Medicine, Faculty of Medicine, Saga University, Saga, 840-0805, Japan; 6Department of Respiratory Medicine, Graduate School of Medicine, Osaka Metropolitan University, Osaka, 545-8585, Japan; 7Department of Respiratory Medicine and Infectious Disease, Graduate School of Medicine, Yamaguchi University, Yamaguchi, 755-8505, JapanCorrespondence: Yoshiaki Minakata, Department of Respiratory Medicine, NHO Wakayama Hospital, Hidaka-Gun, Wakayama, 644-0044, Japan, Tel +81-738-22-3256, Fax +81-738-22-2126, Email [email protected]: Muscle atrophy in the dorsal muscle group (DMG) is associated with physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD). However, no studies have separately evaluated the erector spinae muscle (ESM) and the multifidus muscle (MM) within the DMG, leaving the distinct impact of each muscle on PA unclear.Purpose: This study evaluated the differences in muscle characteristics between ESM and MM in stable patients with COPD.Patients and Methods: In Study 1, we evaluated the relationship between the cross-sectional area of ESM (ESMCSA) and MM (MMCSA) on chest computed tomography and PA parameters. In Study 2, as a pilot study, we analyzed the muscle fatigue characteristics of ESM and MM using a trunk holding test and electromyographic (EMG) power spectrum analysis to evaluate the median frequency (MF) slope. We then evaluated the differences in the MF slopes of both muscles in patients with COPD compared with healthy subjects.Results: Of 77 patients with COPD, the MMCSA was positively associated with the duration of PA at ≥ 3.0 metabolic equivalents (METs) (r=0.279, p=0.014), whereas the ESMCSA was negatively associated with the duration of behavior at 1.0– 1.5 METs (r=− 0.429, p< 0.001). The MF slopes of the MM were significantly lower in COPD patients (n=7) than in healthy subjects (n=28) (p< 0.01), indicating greater fatigue, with no significant differences in MF slopes for ESM or trunk extension holding time.Conclusion: These results indicate that the functional characteristics of the ESM and MM differ in COPD patients. MM was mainly associated with moderate-to-vigorous PA and involved greater fatigue in COPD patients compared to healthy subjects, while the ESM was mainly associated with sedentary behavior.Plain Language Summary: This study investigated the differences in the functional characteristics of the erector spinae muscles (ESM) and multifidus muscles (MM) in patients with chronic obstructive pulmonary disease (COPD) and the differences in the relationship between both muscles and physical activity (PA). In Study 1, the cross-sectional area (CSA) of MM analyzed by chest CT was positively correlated with the duration of moderate to vigorous PA (≥ 3.0 metabolic equivalents (METs)), suggesting a role in dynamic trunk stability such as walking. On the other hand, the CSA of ESM was negatively correlated with the duration of sedentary behavior (1.0-1.5 METs), reflecting its role in maintaining a static posture such as sitting. In Study 2, the muscle fatigue of MM was greater in patients of COPD than in healthy subjects, but that of ESM was not significantly different between both groups. These findings suggest that ESM and MM may play different roles in physical performance. This study provides valuable insight into the role of spinal muscles in patients with COPD and the implementation of rehabilitation to improve PA. Understanding the characteristics of ESM and MM in patients with COPD may help to optimize treatment interventions and improve quality of life.Keywords: COPD, dorsal muscle group, physical activity, electromyography, muscle fatigue, trunk holding test