Department of Healthcare Management, College of Health Science, Korea University, Seoul, Republic of Korea.
Med Sci Monit. 2011 Jul;17(7):CR362-8. doi: 10.12659/msm.881846.
As reported in our previous studies, the complexity of physiologic time series is a sensitive measure of muscle fatigability. This study compared the differences between 2 different analyses following 4 weeks of core stability exercises (CSE) in subjects with and without chronic low back pain (LBP). We examined whether the observed Shannon (information) entropy, as compared with median frequency (MF), was able to differentiate fatigability of the thoracic and lumbar parts of the erector spinae (ES) muscles following the intervention.
MATERIAL/METHODS: In total, 32 subjects participated in this study. There were 13 subjects in the CSE intervention group (average age 50.4 ± 9.1 years) and 19 subjects in the control group (average age 46.6 ± 9.1 years). The CSE group performed the specific exercise intervention, but the control group was asked to maintain their current activity and/or exercise levels. The endurance of the back muscles was determined by using a modified version of the isometric fatigue test as originally introduced by Sorensen.
Pain level decreased significantly for all subjects (F=25.29, p=0.001), but there was no difference between groups (F=0.42, p=0.52). The MF was not different between groups following treatment (F=0.81, p=0.37). Although there was no entropy level changes following treatment (F=0.01, p=0.93), the interactions between muscles and groups following treatment were significant (F=7.25, p=0.01). The entropy level decreased in both thoracic ES muscles following intervention in the exercise group, while remaining the same in the control group.
Although the change in pain level was not different between groups, the Shannon entropy measure more sensitively differentiated the exercise intervention than did MF. In addition, the results also suggested that complexity is related to muscle fatigue, which corresponds to the values of entropy between groups. Further studies are needed to investigate the effectiveness of nonlinear time series of EMG data for fatigability.
正如我们之前的研究报告所述，生理时间序列的复杂性是肌肉疲劳性的敏感测量指标。本研究比较了患有和不患有慢性下腰痛（LBP）的受试者进行 4 周核心稳定性训练（CSE）后的 2 种不同分析的差异。我们检验了与中值频率（MF）相比，观察到的香农（信息）熵是否能够区分干预后竖脊肌（ES）胸段和腰段的疲劳性。
材料/方法：共有 32 名受试者参与了这项研究。CSE 干预组有 13 名受试者（平均年龄 50.4 ± 9.1 岁），对照组有 19 名受试者（平均年龄 46.6 ± 9.1 岁）。CSE 组进行了特定的运动干预，但对照组被要求保持其当前的活动和/或运动水平。使用 Sorensen 最初提出的改良等长疲劳测试来确定背部肌肉的耐力。
所有受试者的疼痛水平均显著下降（F=25.29，p=0.001），但组间无差异（F=0.42，p=0.52）。治疗后 MF 在组间无差异（F=0.81，p=0.37）。尽管治疗后熵水平没有变化（F=0.01，p=0.93），但治疗后的肌肉和组间的相互作用具有显著性（F=7.25，p=0.01）。运动组的胸 ES 肌肉在干预后熵水平下降，而对照组则保持不变。
尽管组间疼痛水平的变化无差异，但香农熵测量比 MF 更敏感地区分运动干预。此外，结果还表明复杂性与肌肉疲劳有关，这与组间熵值相对应。需要进一步的研究来探讨肌电图数据非线性时间序列对疲劳性的有效性。
