Predicting Coordination Variability of Selected Lower Extremity Couplings during a Cutting Movement: An Investigation of Deep Neural Networks with the LSTM Structure

There are still few portable methods for monitoring lower limb joint coordination during the cutting movements (CM). This study aims to obtain the relevant motion biomechanical parameters of the lower limb joints at 90 degrees, 135 degrees, and 180 degrees CM by collecting IMU data of the human lower limbs, and utilizing the Long Short-Term Memory (LSTM) deep neural-network framework to predict the coordination variability of selected lower extremity couplings at the three CM directions. There was a significant (p < 0.001) difference between the three couplings during the swing, especially at 90 degrees vs the other directions. At 135 degrees and 180 degrees, t13-he coordination variability of couplings was significantly greater than at 90 degrees (p < 0.001). It is important to note that the coordination variability of Hip rotation/Knee flexion-extension was significantly higher at 90 degrees than at 180 degrees (p < 0.001). By the LSTM, the CM coordination variability for 90 degrees (CMC = 0.99063, RMSE = 0.02358), 135 degrees (CMC = 0.99018, RMSE = 0.02465) and 180 degrees (CMC = 0.99485, RMSE = 0.01771) were accurately predicted. The predictive model could be used as a reliable tool for predicting the coordination variability of different CM directions in patients or athletes and real-world open scenarios using inertial sensors.