title: Trunk and hip muscle activity in early walkers with and without cerebral palsy--a frequency analysis.
abstract: Poor control of postural muscles is a primary impairment in cerebral palsy (CP), yet core trunk and hip muscle activity has not been thoroughly investigated. Frequency analysis of electromyographic (EMG) signals provides insight about the intensity and pattern of muscle activation, correlates with functional measures in CP, and is sensitive to change after intervention. The objective of this study was to investigate differences in trunk and hip muscle activation frequency in children with CP compared to children with similar amounts of walking experience and typical development (TD). EMG data from 31 children (15 with CP, 16 with TD) were recorded from 16 trunk and hip muscles bilaterally. A time-frequency pattern was generated using the continuous wavelet transform and instantaneous mean frequency (IMNF) was calculated at each interval of the gait cycle. Functional principal component analysis (PCA) revealed that IMNF was significantly higher in the CP group throughout the gait cycle for all muscles. Additionally, stride-to-stride variability was higher in the CP group. This evidence demonstrated altered patterns of trunk and hip muscle activation in CP, including increased rates of motor unit firing, increased number of recruited motor units, and/or decreased synchrony of motor units. These altered muscle activation patterns likely contribute to muscle fatigue and decreased biomechanical efficiency in children with CP.
authors.affiliation: Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD 20892, United States.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Prosser
authors.forename: Samuel C K
authors.initials: SC
authors.lastname: Lee
authors.forename: Mary F
authors.initials: MF
authors.lastname: Barbe
authors.forename: Ann F
authors.initials: AF
authors.lastname: VanSant
authors.forename: Richard T
authors.initials: RT
authors.lastname: Lauer
mesh_terms: D001415:Back / Q000503:physiopathology*; D002547:Cerebral Palsy / Q000150:complications / Q000503:physiopathology*; D002675:Child, Preschool; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D013909:Thorax / Q000503:physiopathology; D016138:Walking
references.citation: J Orthop Res. 1994 Nov;12(6):758-68
references.pmid: 7983551
references.citation: MMWR Morb Mortal Wkly Rep. 2004 Jan 30;53(3):57-9
references.pmid: 14749614
references.citation: J Appl Physiol (1985). 1999 Mar;86(3):1040-7
references.pmid: 10066721
references.citation: Neural Plast. 2005;12(2-3):197-203; discussion 263-72
references.pmid: 16097487
references.citation: Clin Biomech (Bristol, Avon). 2008 May;23(4):442-9
references.pmid: 18082920
references.citation: Disabil Rehabil. 2006 Feb 28;28(4):183-91
references.pmid: 16467053
references.citation: Gait Posture. 2005 Nov;22(3):189-97
references.pmid: 16214658
references.citation: J Am Osteopath Assoc. 2007 Jun;107(6):226-32
references.pmid: 17635903
references.citation: Gait Posture. 1998 Mar 1;7(2):125-130
references.pmid: 10200382
references.citation: Electromyogr Clin Neurophysiol. 1996 Dec;36(8):487-94
references.pmid: 8985677
references.citation: J Appl Physiol (1985). 2004 Apr;96(4):1486-95
references.pmid: 15016793
references.citation: Gait Posture. 2007 Sep;26(3):420-7
references.pmid: 17161603
references.citation: Arch Phys Med Rehabil. 2007 Sep;88(9):1114-20
references.pmid: 17826455
references.citation: Med Sci Sports Exerc. 1996 Dec;28(12):1498-504
references.pmid: 8970144
references.citation: J Electromyogr Kinesiol. 2000 Oct;10(5):361-74
references.pmid: 11018445
references.citation: Gait Posture. 2007 Apr;25(4):580-9
references.pmid: 16876416
references.citation: J Electromyogr Kinesiol. 1992;2(1):15-25
references.pmid: 20870523
references.citation: Electromyogr Clin Neurophysiol. 1998 Jan-Feb;38(1):51-8
references.pmid: 9532434
references.citation: Dev Med Child Neurol. 2005 May;47(5):329-36
references.pmid: 15892375
references.citation: Dev Med Child Neurol Suppl. 2007 Feb;109:8-14
references.pmid: 17370477
references.citation: Clin Biomech (Bristol, Avon). 2009 Mar;24(3):236-45
references.pmid: 18995937
references.citation: J Biomech. 2007;40(12):2738-43
references.pmid: 17328900
references.citation: J Pediatr Orthop. 2001 Nov-Dec;21(6):784-9
references.pmid: 11675555
references.citation: Electromyogr Clin Neurophysiol. 1984 Mar-Apr;24(3):225-40
references.pmid: 6714151
references.citation: J Electromyogr Kinesiol. 2003 Oct;13(5):461-8
references.pmid: 12932420
references.citation: Phys Ther. 2008 Mar;88(3):363-75
references.pmid: 18174446