title: Interpreting principal components in biomechanics: representative extremes and single component reconstruction.
abstract: Principal component analysis is a powerful tool in biomechanics for reducing complex multivariate datasets to a subset of important parameters. However, interpreting the biomechanical meaning of these parameters can be a subjective process. Biomechanical interpretations that are based on visual inspection of extreme 5th and 95th percentile waveforms may be confounded when extreme waveforms express more than one biomechanical feature. This study compares interpretation of principal components using representative extremes with a recently developed method, called single component reconstruction, which provides an uncontaminated visualization of each individual biomechanical feature. Example datasets from knee joint moments, lateral gastrocnemius EMG, and lumbar spine kinematics are used to demonstrate that the representative extremes method and single component reconstruction can yield equivalent interpretations of principal components. However, single component reconstruction interpretation cannot be contaminated by other components, which may enhance the use and understanding of principal component analysis within the biomechanics community.
authors.affiliation: Department of Mechanical and Materials Engineering, Queen's University, McLaughlin Hall, 130 Stuart Street, Kingston, Ontario, K7L 3N6, Canada; Human Mobility Research Centre, Syl & Molly Apps Medical Research Centre, Kingston General Hospital & Queen's University, Kingston, Ontario, K7L 2V7, Canada. Electronic address: Brandon@me.queensu.ca.
authors.forename: Scott C E
authors.initials: SC
authors.lastname: Brandon
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Graham
authors.forename: Sivan
authors.initials: S
authors.lastname: Almosnino
authors.forename: Erin M
authors.initials: EM
authors.lastname: Sadler
authors.forename: Joan M
authors.initials: JM
authors.lastname: Stevenson
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Deluzio
mesh_terms: D001696:Biomechanical Phenomena; D003627:Data Interpretation, Statistical; D004576:Electromyography / Q000706:statistics & numerical data*; D005684:Gait / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007719:Knee Joint / Q000502:physiology*; D008159:Lumbar Vertebrae / Q000502:physiology*; D008954:Models, Biological; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000502:physiology*; D025341:Principal Component Analysis; D016474:Weight-Bearing / Q000502:physiology
keywords: Biomechanics; Gait; Interpretation; Lifting; Multivariate; Principal component analysis; Waveforms