title: Asymmetry between lower limbs during rested and fatigued state running gait in healthy individuals.
abstract: Although normal gait is often considered symmetrical in healthy populations, differences between limbs during walking suggest that limbs may be used preferentially for braking or propulsion. The purpose of this study was to evaluate kinematic and kinetic variables, at both rested state and following a two-stage treadmill fatiguing run, for asymmetry between limbs. Kinematic (240Hz) and kinetic (960Hz) running data were collected bilaterally for 20 physically active individuals at both rested and fatigued states. Symmetry angles were calculated to quantify asymmetry magnitude at rested and fatigued states. Paired t-tests were used to evaluate differences between right and left limbs at rested and fatigued states, as well as rested and fatigued states symmetry angles. Variables that have been previously associated with the development of overuse injuries, such as knee internal rotation, knee stiffness, loading rate, and adduction free moment, were found to be significantly different between limbs at both rested and fatigued states. Significant differences in vertical stiffness were found, potentially indicating functional asymmetry during running. Symmetry angle was used to investigate changes in percentage of asymmetry at rested and fatigued states. Small (1-6%), but significant decreases in vertical stiffness, loading rate, and free moment symmetry angles indicate that these variables may become more symmetrical with fatigue. Knee internal rotation and knee stiffness became more asymmetrical with fatigue, increasing by 14% and 5.3%, respectively. The findings of the current study indicate that fatigue induced changes in gait may progress knee movement pattern asymmetry.
authors.affiliation: Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, Honolulu HI, USA; Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, Las Vegas NV, USA. Electronic address: kara.radzak@unlv.edu.
authors.forename: Kara N
authors.initials: KN
authors.lastname: Radzak
authors.affiliation: Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, Honolulu HI, USA.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Putnam
authors.affiliation: Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, Honolulu HI, USA.
authors.forename: Kaori
authors.initials: K
authors.lastname: Tamura
authors.affiliation: Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, Honolulu HI, USA.
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Hetzler
authors.affiliation: Department of Kinesiology and Rehabilitation Science, University of Hawaii, Manoa, Honolulu HI, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Stickley
mesh_terms: D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D018763:Muscle Fatigue; D012016:Reference Values; D012420:Running; D055815:Young Adult
keywords: Asymmetry; Fatigue; Running; Symmetry; Vertical stiffness