The assessment of primary joint in 2.2 Hz hopping using factor analysis

Abstract

Abstract: Background and aim: This study aimed to investigate the role of the ankle joint in 2.2 Hz hopping mechanics using factor analysis. Materials and Methods: Thirty healthy men used in this study performed hopping on the force platform and kinematic data measured using 6 Motion Analysis cameras. Knee and ankle angular displacement and velocity, stiffness, and mechanical energy calculated, and for statistical analysis, we use principal component analysis, Pearson coefficient, and independent t-test. Results: The results of this study show that ankle variables alongside leg stiffness put in PC1 (38% of variances) and knee variables put in PC2. There are significant relation-ships between the ankle and leg stiffness, ankle kinematic, and mechanical work in negative and positive phases and knee mechanical energy in the negative and positive phases (P<0.05). Independent t-test shows significant differences between the ankle and knee joints in all biomechanical parameters, hence except joint stiffness, ankle joint has higher kinematic and mechanical work in both phases (P<0.05). Discussion: Based on correlations be-tween negative and positive phases of the hopping, ankle joint could better utilize the eccentric phase for increase concentric output during hopping. Conclusion: The result of PCA showed the importance of ankle joint in regulat-ing leg stiffness during hopping.