@article{Samanta_Mukherjee_2021, title={Surface Electromyography Based Core Muscle Fatigue Analysis During Repetitive Plank Using Multivariate Dimensionality Reduction Methods in Boys Aged 12-14}, volume={21}, url={https://tmfv.com.ua/journal/article/view/1555}, DOI={10.17309/tmfv.2021.3.09}, abstractNote={<p><strong>The aims of the study</strong> were: 1. To analyse the discriminative power of neuromuscular components for classifying the pre and post muscle fatigued states. 2. To examine whether the modification of neural recruitment strategies become more/less heterogeneous due to fatigue. 3. To research the effect of Erector Spinae (ES) muscle activity collectively with Rectus Abdominis (RA) and External Oblique (EO) muscle activity to identify the reduced spine stability during fatiguing Plank.<span class="Apple-converted-space"> </span></p> <p><strong>Material and methods.</strong> Twelve boys (age – 12-14 years, height 148.75 ± 10 cm, body mass 38.9 ± 7.9 kg) participated in the study. Multivariate Discriminant Analysis (DA) and Principal Component Analysis (PCA) were applied to identify the changes in the pattern of the electromyographic signals during muscle fatigue. In DA the Wilks’ lambda, p-value, canonical correlation, classification percentage and structure matrix were used. To evaluate the component validity the standard limit for Kaiser-Meyer-Olkin (KMO) was set at ≥0.529 and the p-value of Bartlett’s test was ≤0.001. The eigenvalues ≥1 were used to determine the number of Principal Components (PCs). The satisfactory percentage of non-redundant residuals were set at ≤50% with standard value >0.05. The absolute value of average communality (x̄ h<sup>2</sup>) and component loadings were set at ≥0.6, ≥0.4 respectively.<span class="Apple-converted-space"> </span></p> <p><strong>Results.</strong> Standardized canonical discriminant analysis showed that pre and post fatigued conditions were significantly different (p = 0.000, Wilks’ lambda = 0.297, <em>χ</em><sup>2 </sup>= 24.914, <em>df</em>=3). The structure matrix showed that the parameter that correlated highly with the discriminant function was ES ARV (0.514). The results showed that the classification accuracy was 95.8% between fatigued conditions. In PCA the KMO values were reduced [0.547<sub>Pre fatigue</sub> vs. 0.264<sub>Post fatigue</sub>]; the value of Bartlett’s sphericity test was in pre <em>χ</em><sup>2 </sup>= 90.72 (p = 0.000) and post fatigue <em>χ</em><sup>2 </sup>= 85.32 (p = 0.000); The Promax criterion with Kaiser Normalization was applied because the component rotation was non-orthogonal [Component Correlation Matrix (r<sub>CCM</sub>) = 0.520 <sub>Pre fatigue</sub> >0.3<sub>Absolute</sub><0.357<sub>Post fatigue</sub>]. In pre fatigue two PCs (cumulative s<sup>2 </sup>– 80.159%) and post fatigue three PCs (cumulative s<sup>2 </sup>– 83.845%) had eigenvalues ≥1. The x̄ h<sup>2</sup> increased [0.802 <sub>Pre fatigue</sub> vs. 0.838 <sub>Post fatigue</sub>] and the percentage of nonredundant residuals reduced [50% <sub>Pre fatigue</sub> vs. 44% <sub>Post fatigue</sub>] from pre to post fatigue.<span class="Apple-converted-space"> </span></p> <p><strong>Conclusions.</strong> The variability and heterogeneity increase in the myoelectric signals due to fatigue. The co-activity of antagonist ES muscle is significantly sensitive to identify the deteriorating spine stability during the fatiguing Plank. Highly correlated motor unit recruitment strategies between ES and RA, providing supportive evidence to the concept of shared agonist-antagonist motoneuron pool or “Common Drive” phenomenon during fatigue.</p>}, number={3}, journal={Physical Education Theory and Methodology}, author={Samanta, Abir and Mukherjee, Sabyasachi}, year={2021}, month={Sep.}, pages={253–263} }