Principal component analysis of the power developed in the flexion/extension muscles of the hip in able-bodied gait

This study was undertaken to demonstrate how principal component analysis ( PCA) can be used: (a) to detect the main functional structure of actions ta ken by hip extensors and flexors during two consecutive gait cycles of able -bodied subjects, and (b) to determine whether or not symmetrical behaviour exists between right and left hip muscle power activity. Twenty young, hea lthy male subjects walked along a 13 m path at a freely-chosen speed. Apply ing curve structure detection methods such as PCA to walking patterns can p rovide insight into the functional tasks accomplished by the lower limbs of able-bodied and disabled subjects PCA was applied as a classification and curve structure detection method to kip sagittal muscle power calculated fo r the right and left lower limbs. Over 70% of the information provided by t he first four principal components (PCs) was chosen for further biomechanic al interpretation. PC1 for both right and left sides mainly described the a ction taken by the hip extensors/flexors corresponding to the vertical comp onent of ground force on the respective limbs during mid-stance. Propulsion and limb preparation were identified as the second and third tasks attribu ted to right hip muscle power, while between limb co-ordination was recogni sed as the second and third functional tasks of the left hip extensors/flex ors. Balance was identified as the fourth main functional contribution of t he hip extensors/flexors at the right limb while for the left limb, these m uscles were mainly responsible for preparing the limb to enter into new gai t cycle. PCA was able to identify the four main functional contributions of hip sagittal muscle power during able-bodied gait. PCA was also able to ex amine the existence of functional asymmetry in gait by highlighting differe nt task priorities at the hip level for the right and left lower limbs. (C) 2001 IPEM. Published by Elsevier Science Ltd. All rights reserved.