Gait is a complex motor activity that reflects the interaction between neuromuscular control and mechanical loading. This study evaluated the ability of electromyographic (EMG) and kinetic gait parameters to classify observations according to a study-specific index of locomotor performance. A multimodal gait dataset comprising motion-capture, ground reaction force (GRF), and surface EMG measurements was analyzed. EMG features derived from the gluteus maximus and soleus muscles included root mean square (RMS), integrated EMG (iEMG), median frequency (MDF), and a muscle co-contraction ratio. Kinetic features included peak and mean vertical GRF, force impulse, GRF asymmetry, center-of-pressure (COP) path length, and COP velocity. A study-specific Performance Index was constructed from normalized cadence, GRF, COP stability, and asymmetry components and used to categorize observations into Low, Medium, and High performance classes. A total of 1,143 observations were analyzed using a stratified 70:30 training–testing split. Random Forest and XGBoost were applied for EMG-based classification and feature assessment, whereas Random Forest, XGBoost, Support Vector Machine (SVM), and Nearest Mean were evaluated for kinetic-based classification. SHapley Additive exPlanations (SHAP) were used to interpret model predictions, while Spearman correlation analysis was performed to examine EMG–kinetic relationships. The EMG-based Random Forest and XGBoost models both achieved accuracies exceeding 99%. For kinetic data, SVM achieved the highest accuracy (93.59%), followed by Random Forest and XGBoost (90.38% each), whereas Nearest Mean achieved 70.55%. Soleus iEMG was among the most informative EMG features, while GRF magnitude and force impulse were the dominant kinetic features. The strongest EMG–kinetic association was observed between gluteus maximus RMS and right-limb force impulse (r = −0.421). Overall, the findings demonstrate the complementary value of neuromuscular and kinetic information for the study-specific classification of locomotor performance.
