Original article| Volume 91, ISSUE 10, P1593-1601, October 2010

Reliability of Center of Pressure Measures for Assessing the Development of Sitting Postural Control in Infants With or at Risk of Cerebral Palsy


      Kyvelidou A, Harbourne RT, Shostrom VK, Stergiou N. Reliability of center of pressure measures for assessing the development of sitting postural control in infants with or at risk of cerebral palsy.


      To establish the test-retest reliability of linear and nonlinear measures, including intra- and intersession reliability, when used to analyze the center of pressure (COP) time series during the development of infant sitting postural control in infants with or at risk for cerebral palsy (CP).


      Longitudinal study.


      University hospital laboratory.


      Infants with or at risk for CP (N=18; mean age ± SD at entry into the study, 13.7±3.6mo).


      Not applicable.

      Main Outcome Measures

      Infant sitting COP data were recorded for 3 trials at each session (2 sessions for each month within 1 week) for 4 consecutive months. The linear COP parameters of the root mean square, the range of sway for both the anterior-posterior and the medial-lateral directions, and the sway path were calculated. In addition, the nonlinear parameters of approximate entropy, Lyapunov exponent (LyE), and the correlation dimension for both directions were also calculated. Intra- and intersession reliability was computed by the intraclass correlation coefficient (ICC).


      Regarding nonlinear measures, LyE showed high intra- and intersession ICC values in comparison with all other parameters evaluated. Intrasession and intersession reliability increased overall in the last 2 months of data collection and as sitting posture improved.


      Our results suggested that the methodology presented is a reliable way of examining the development of sitting postural control in infants with or at risk for CP, and the reliability results generally parallel values found in sitting postural behavior in typical infants. Therefore, this methodology may be helpful in examining efficacy of therapy protocols directed at advancing sitting postural control in infants with motor developmental delays.

      Key Words

      List of Abbreviations:

      AP (anterior/posterior), ApEn (approximate entropy), COP (center of pressure), CP (cerebral palsy), ICC (intraclass correlation coefficient), LyE (Lyapunov exponent), ML (medial/lateral), RMS (root mean square)
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Archives of Physical Medicine and Rehabilitation
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Hughes I.
        • Newton R.
        Genetic aspects of cerebral palsy.
        Dev Med Child Neurol. 1992; 34: 80-86
        • Woollacott M.H.
        • Shumway-Cook A.
        Postural dysfunction during standing and walking in children with cerebral palsy: what are the underlying problems and what new therapies might improve balance?.
        Neural Plast. 2005; 12: 211-219
        • Campbell S.K.
        The child's development of functional movement.
        in: Campbell S.K. Vander Linden D.W. Palisano R.J. Physical therapy for children. 3rd ed. W.B. Saunders Company, Missouri: St. Louis (MO)2006: 33-76
        • van der Heide J.C.
        • Hadders-Algra M.
        Postural muscle dyscoordination in children with cerebral palsy.
        Neural Plast. 2005; 12: 197-203
        • Brogren E.
        • Hadders-Algra M.
        • Forssberg H.
        Postural control in sitting children with cerebral palsy.
        Neurosci Biobehav Rev. 1998; 22: 591-596
        • Hadders-Algra M.
        • van der Fits I.B.
        • Stremmelaar E.F.
        • Touwen B.C.
        Development of postural adjustments during reaching in infants with CP.
        Dev Med Child Neurol. 1999; 41: 766-776
        • Campbell S.K.
        The infant at risk for developmental disability.
        in: Campbell S.K. Decision making in pediatric neurologic physical therapy. Churchill Livingstone, Philadelphia1999: 260-332
        • Deffeyes J.E.
        • Kochi N.
        • Harbourne R.T.
        • Kyvelidou A.
        • Stuberg W.A.
        • Stergiou N.
        Nonlinear detrended fluctuation analysis of sitting center-of-pressure data as an early measure of motor development pathology in infants.
        Nonlinear Dynamics Psychol Life Sci. 2009; 3: 351-368
        • Massion J.
        Movement, posture, and equilibrium: interaction and coordination.
        Prog Neurobiol. 1992; 38: 35-56
        • Donker F.S.
        • Roerdink M.
        • Greven A.J.
        • Beek P.J.
        Regularity of center-of-pressure trajectories depends on the amount of attention invested in postural control.
        Exp Brain Res. 2007; 181: 1-11
        • Rocchi L.
        • Chiari L.
        • Horak F.B.
        Effects of deep brain stimulation and levodopa on postural sway in Parkinson's disease.
        J Neurol Neurosurg Psychiatry. 2002; 73: 267-274
        • Riach C.L.
        • Hayes K.C.
        Maturation of postural sway in young children.
        Dev Med Child Neurol. 1987; 29: 650-658
        • Cherng R.J.
        • Su F.C.
        • Chen J.J.
        • Kuan T.S.
        Performance of static standing balance in children with spastic diplegic cerebral palsy under altered sensory environments.
        Am J Phys Med Rehabil. 2007; 78: 336-343
        • Brouwer B.
        • Culham E.G.
        • Liston R.A.L.
        • Grant T.
        Normal variability of postural measure: implications for the reliability of relative balance performance outcomes.
        Scand J Rehab Med. 1998; 30: 131-137
        • Lafond L.
        • Corriveau H.
        • He′bert R.
        • Prince M.F.
        Intrasession reliability of center of pressure measures of postural steadiness in healthy elderly people.
        Arch Phys Med Rehabil. 2004; 85: 896-901
        • Liao H.
        • Mao P.
        • Hwang A.
        Test-retest reliability of balance tests in children with cerebral palsy.
        Dev Med Child Neurol. 2001; 43: 180-186
        • Baker C.P.
        • Newstead A.H.
        • Mossberg K.A.
        • Nicodemus C.L.
        Reliability of static standing balance in nondisabled children: comparison of two methods of measurement.
        Pediatr Rehabil. 1998; 2: 15-20
        • Stergiou N.
        • Harbourne R.T.
        • Cavanaugh J.T.
        Optimal movement variability: a new theoretical perspective for neurologic physical therapy.
        J Neurol Phys Ther. 2006; 30: 120-129
        • Harbourne R.T.
        • Stergiou N.
        Nonlinear analysis of the development of sitting postural control.
        Dev Psychobiol. 2003; 42: 368-377
        • Harbourne R.T.
        • Deffeyes J.E.
        • Kyvelidou A.
        • Stergiou N.
        Complexity of postural control in infants: linear and nonlinear features revealed by principal component analysis.
        Nonlinear Dynamics Psychol Life Sci. 2009; 13: 123-144
        • Sosnoff J.J.
        • Newell K.M.
        Are age-related increases in force variability due to decrements in strength?.
        Exp Brain Res. 2006; 174: 86-94
        • Harbourne T.H.
        • Stergiou N.
        Movement variability and the use of nonlinear tools: principles to guide physical therapist practice.
        Phys Ther. 2009; 89: 267-282
        • Bertenthal B.I.
        • Rose J.L.
        • Bai D.L.
        Perception-action coupling in the development of visual control of posture.
        J Exp Psychol. 1997; 23: 1631-1643
        • Boker S.M.
        • Schreiber T.
        • Pompe B.
        • Bertenthal B.I.
        Nonlinear analysis of perceptual-motor coupling in the development of postural control.
        in: Kantz H. Kurths J. Mayer-Kress G. Nonlinear techniques in physiological time series analysis. Springer, Heidelberg, Germany1998
        • Kyvelidou A.
        • Harbourne R.T.
        • Stuberg W.A.
        • Sun J.
        • Stergiou N.
        Reliability of center of pressure measures for assessing the development of sitting postural control.
        Arch Phys Med Rehabil. 2009; 90: 1176-1184
        • Russell D.
        • Rosenbaum P.
        • Gowland C.
        • et al.
        Gross motor function measure.
        McMaster Univ, Ontario, Canada1993
        • Grassberger P.
        • Procaccia I.
        Measuring the strangeness of strange attractors.
        Physica D. 1983; 9: 189-208
        • Pincus S.M.
        • Gladstone I.M.
        • Ehrenkranz R.A.
        A regularity statistic for medical data analysis.
        J Clin Monit. 1991; 7: 335-345
        • Prieto T.E.
        • Myklebust J.B.
        • Hoffmann R.G.
        • Lovett E.G.
        • Myklebust B.M.
        Measures of postural steadiness: differences between healthy young and elderly adults.
        IEEE Trans Biomed Eng. 1996; 43: 956-966
        • Chiari L.
        • Rocchi L.
        • Capello A.
        Stabilometric parameters are affected by anthropometry and foot placement.
        Clin Biomech. 2002; 17: 666-677
        • Sprott J.C.
        • Rowlands G.
        Chaos data analyzer: the professional version.
        Physics Academic Software, Raleigh1998
        • Stergiou N.
        • Buzzi U.H.
        • Kurz M.J.
        • Heidel J.
        Nonlinear tools in human movement.
        in: Stergiou N. Innovative analyses for human movement. Human Kinetics Publishers, Champaign2004: 63-90
        • Mitra S.
        • Riley M.A.
        • Turvey M.T.
        Chaos in human rhythmic movement.
        J Mot Behav. 1997; 29: 195-198
        • Pincus S.M.
        Approximate entropy as a measure of system complexity.
        Proc Natl Acad Sci U S A. 1991; 88: 2297-2301
        • Shrout P.E.
        • Fleiss J.L.
        Intraclass correlations: uses in assessing rater reliability.
        Psychol Bull. 1979; 86: 420-428
        • Rosner B.
        Fundamentals of biostatistics.
        in: 5th ed. Duxbury Thomsom Learning, 2000: 563
        • Hughes M.A.
        • Duncan P.W.
        • Rose D.K.
        • Chandler J.M.
        • Studenski S.A.
        The relationship of postural sway to sensorimotor function, functional performance, and disability in the elderly.
        Arch Phys Med Rehabil. 1996; 77: 567-572
        • Doyle T.L.
        • Newton R.U.
        • Burnett A.F.
        Reliability of traditional and fractal dimension measures of quiet stance center of pressure in young, healthy people.
        Arc Phys Med Rehabil. 2005; 86: 2034-2040