Joints (anatomy) 8 Muscle Auto-regressive 3 Backpropagation 3 Complex nonlinear system 3 Mean square error 3 Neural networks 3 Nonlinear systems 3 Back propagation neural networks 2 Backpropagation algorithms 2 Gait analysis 2 Joint moment 2 Logical modeling 2 Lower limb 2 Muscle modeling 2 Neural network model 2 Non-linear model 2 artificial neural network 2 backpropagation 2 nonlinear autoregressive 2 quadriceps muscle 2 Accident prevention 1 Accidental falls 1 Age differences 1 Analog to digital conversion 1 Analog to digital converters 1 Biceps femoris 1 Biomechanics 1 Botulinum toxin 1 Botulinum toxins 1