Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:3623-3627. doi: 10.1109/EMBC48229.2022.9872010.
In this work, four different algorithms (fast Fourier transform FFT, short-time Fourier transform STFT, continuous wavelet transform CWT, and instantaneous frequency IF) for calculating median frequency (MDF) from surface EMG signals were investigated for studying muscle fatigue during a on-water rowing training. The study protocol included 5 consecutive parts with increasing stroke rate. Six athletes participated in the study aged 36.6+-14.6 years and a rowing experience of 6 to 35 years. We considered eight muscles: biceps brachii right, biceps brachii left, latissimus dorsi right, latissimus dorsi left, erector spinae right, erector spinae left, rectus femoris and biceps femoris. By applying Friedmann test, we found a significant difference in MDF behavior between algorithms in assessing muscle fatigue . Correlation analyses showed significant correlations between muscle activity duration t and MDF, which differs for the four considered algorithms and should be taken into account in further experiments. With CWT showing the smallest correlation to t it might be more robust against time window variations. Our study provides a basis for the development of improved methods for more robust, non-invasive, and continuous detection of muscle fatigue in experiments with dynamic on-water rowing study designs.
在这项工作中，研究了四种不同的算法（快速傅里叶变换 FFT、短时傅里叶变换 STFT、连续小波变换 CWT 和瞬时频率 IF），用于从表面肌电信号中计算中值频率（MDF），以研究水上划船训练过程中的肌肉疲劳。研究方案包括 5 个连续部分，每个部分的划频逐渐增加。6 名年龄在 36.6+-14.6 岁、划船经验 6 至 35 年的运动员参加了这项研究。我们考虑了 8 块肌肉：右侧肱二头肌、左侧肱二头肌、右侧背阔肌、左侧背阔肌、右侧竖脊肌、左侧竖脊肌、股直肌和股二头肌。通过应用弗里德曼检验，我们发现，在评估肌肉疲劳方面，不同算法的 MDF 行为存在显著差异。相关分析表明，MDF 与肌肉活动持续时间 t 之间存在显著相关性，这在四种考虑的算法中有所不同，在进一步的实验中应予以考虑。CWT 与 t 的相关性最小，因此它可能对时间窗变化更稳健。我们的研究为开发更稳健、非侵入性和连续检测水上划船动态实验中肌肉疲劳的改进方法提供了基础。
