Balance Control and Energetics of Powered Exoskeleton-Assisted Sit-to-Stand Movement in Individuals With Paraplegic Spinal Cord Injury

Published:April 27, 2018DOI:



      To quantify the effects of initial hip angle and angular hip velocity settings of a lower-limb wearable robotic exoskeleton (WRE) on the balance control and mechanical energy requirements in patients with paraplegic spinal cord injuries (SCIs) during WRE-assisted sit-to-stand (STS).


      Observational, cross-sectional study.


      A university hospital gait laboratory with an 8-camera motion analysis system, 3 forceplates, a pair of instrumented crutches, and a WRE.


      Patients (N=12) with paraplegic SCI.


      Not applicable.

      Main Outcome Measures

      The inclination angle (IA) of the body’s center of mass (COM) relative to the center of pressure (COP), and the rate of change of IA (RCIA) for balance control, and the mechanical energy and forward COM momentum before and after seat-off for energetics during WRE-assisted STS were compared between conditions with 2 initial hip angles (105° and 115°) and 3 initial hip angular velocities (800, 1000, 1200 rpm).


      No interactions between the main factors (ie, initial hip angle vs angular velocity) were found for any of the calculated variables. Greater initial hip angle helped the patients with SCI move the body forward with increased COM momentum but reduced RCIA (P<.05). With increasing initial angular hip velocity, the IA and RCIA after seat-off (P<.05) increased linearly while total mechanical energy reduced linearly (P<.05).


      The current results suggest that a greater initial hip angle with smaller initial angular velocity may provide a favorable compromise between momentum transfer and balance of the body for people with SCI during WRE-assisted STS. The current data will be helpful for improving the design and clinical use of the WRE.


      List of abbreviations:

      COM (body’s center of mass), COP (center of pressure), GRF (ground reaction force), IA (inclination angle), RCIA (rate of change of IA), SCI (spinal cord injury), STS (sit-to-stand), WRE (wearable robotic exoskeleton)
      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


        • Organization W.H.
        • Society I.S.C.
        International perspectives on spinal cord injury.
        World Health Organization, Geneva2013
        • Franceschini M.
        • Baratta S.
        • Zampolini M.
        • Loria D.
        • Lotta S.
        Reciprocating gait orthoses: a multicenter study of their use by spinal cord injured patients.
        Arch Phys Med Rehabil. 1997; 78: 582-586
        • Harkema S.J.
        • Schmidt-Read M.
        • Lorenz D.J.
        • Edgerton V.R.
        • Behrman A.L.
        Balance and ambulation improvements in individuals with chronic incomplete spinal cord injury using locomotor training–based rehabilitation.
        Arch Phys Med Rehabil. 2012; 93: 1508-1517
        • Kawashima N.
        • Taguchi D.
        • Nakazawa K.
        • Akai M.
        Effect of lesion level on the orthotic gait performance in individuals with complete paraplegia.
        Spinal Cord. 2006; 44: 487-494
        • Nene A.
        • Hermens H.
        • Zilvold G.
        Paraplegic locomotion: a review.
        Spinal Cord. 1996; 34: 507-524
        • Alemdaroglu E.
        • Mandiroglu S.
        • Ucan H.
        • Celik C.
        The continuity of orthosis use by paraplegics which had been prescribed during in-patient rehabilitation. Turkiye Fiziksel Tip Ve Rehabilitasyon Dergisi-Turkish.
        J Phys Med Rehabil. 2014; 60: 223-230
        • Behrman A.L.
        • Harkema S.J.
        Locomotor training after human spinal cord injury: a series of case studies.
        Phys Ther. 2000; 80: 688-700
        • Arazpour M.
        • Bani M.
        • Hutchins S.
        • Jones R.
        The physiological cost index of walking with mechanical and powered gait orthosis in patients with spinal cord injury.
        Spinal Cord. 2013; 51: 356-359
        • Benson I.
        • Hart K.
        • Tussler D.
        • van Middendorp J.J.
        Lower-limb exoskeletons for individuals with chronic spinal cord injury: findings from a feasibility study.
        Clin Rehabil. 2016; 30: 73-84
        • Esquenazi A.
        • Talaty M.
        • Packel A.
        • Saulino M.
        The ReWalk powered exoskeleton to restore ambulatory function to individuals with thoracic-level motor-complete spinal cord injury.
        Am J Phys Med Rehabil. 2012; 91: 911-921
        • Hartigan C.
        • Kandilakis C.
        • Dalley S.
        • et al.
        Mobility outcomes following five training sessions with a powered exoskeleton.
        Top Spinal Cord Inj Rehabil. 2015; 21: 93-99
        • Hornby T.G.
        • Zemon D.H.
        • Campbell D.
        Robotic-assisted, body-weight-supported treadmill training in individuals following motor incomplete spinal cord injury.
        Phys Ther. 2005; 85: 52-66
        • Zeilig G.
        • Weingarden H.
        • Zwecker M.
        • Dudkiewicz I.
        • Bloch A.
        • Esquenazi A.
        Safety and tolerance of the ReWalk™ exoskeleton suit for ambulation by people with complete spinal cord injury: a pilot study.
        J Spinal Cord Med. 2012; 35: 96-101
        • Miller L.E.
        • Zimmermann A.K.
        • Herbert W.G.
        Clinical effectiveness and safety of powered exoskeleton-assisted walking in patients with spinal cord injury: systematic review with meta-analysis.
        Med Devices. 2016; 9: 455-466
        • Butler P.B.
        • Nene A.V.
        • Major R.E.
        Biomechanics of transfer from sitting to the standing position in some neuromuscular diseases.
        Physiotherapy. 1991; 77: 521-525
        • Doorenbosch C.A.
        • Harlaar J.
        • Roebroeck M.E.
        • Lankhorst G.J.
        Two strategies of transferring from sit-to-stand; the activation of monoarticular and biarticular muscles.
        J Biomech. 1994; 27: 1299-1307
        • Fujimoto M.
        • Chou L.-S.
        Dynamic balance control during sit-to-stand movement: an examination with the center of mass acceleration.
        J Biomech. 2012; 45: 543-548
        • Fujimoto M.
        • Chou L.-S.
        Region of stability derived by center of mass acceleration better identifies individuals with difficulty in sit-to-stand movement.
        Ann Biomed Eng. 2014; 42: 733-741
        • Hughes M.A.
        • Myers B.S.
        • Schenkman M.L.
        The role of strength in rising from a chair in the functionally impaired elderly.
        J Biomech. 1996; 29: 1509-1513
        • Hughes M.A.
        • Schenkman M.L.
        Chair rise strategy in the functionally impaired elderly.
        J Rehabil Res Dev. 1996; 33: 409-412
        • Scarborough D.M.
        • McGibbon C.A.
        • Krebs D.E.
        Chair rise strategies in older adults with functional limitations.
        J Rehabil Res Dev. 2007; 44: 33-41
        • Schenkman M.
        • Berger R.A.
        • Riley P.O.
        • Mann R.W.
        • Hodge W.A.
        Whole-body movements during rising to standing from sitting.
        Phys Ther. 1990; 70: 638-648
        • Chang C.-F.
        • Wang T.-M.
        • Lo W.-C.
        • et al.
        Balance control during level walking in children with spastic diplegic cerebral palsy.
        Biomed Eng-App Bas C. 2011; 23: 509-517
        • Hong S.W.
        • Leu T.H.
        • Li J.D.
        • Wang T.M.
        • Ho W.P.
        • Lu T.W.
        Influence of inclination angles on intra- and inter-limb load-sharing during uphill walking.
        Gait Posture. 2014; 39: 29-34
        • Hong S.-W.
        • Wu C.-H.
        • Lu T.-W.
        • et al.
        Biomechanical strategies and the loads in the lower limbs during downhill walking with different inclination angles.
        Biomed Eng-App Bas C. 2014; 26 (1450071-1-1450071-9)
        • Lu H.L.
        • Lu T.W.
        • Lin H.C.
        • Chan W.P.
        Comparison of body’s center of mass motion relative to center of pressure between treadmill and over-ground walking.
        Gait Posture. 2017; 53: 248-253
        • Lu H.L.
        • Lu T.W.
        • Lin H.C.
        • Hsieh H.J.
        • Chan W.P.
        Effects of belt speed on the body’s center of mass motion relative to the center of pressure during treadmill walking.
        Gait Posture. 2017; 51: 109-115
        • Janssen W.G.
        • Bussmann H.B.
        • Stam H.J.
        Determinants of the sit-to-stand movement: a review.
        Phys Ther. 2002; 82: 866-879
        • American Physical Therapy Association
        Guide to physical therapist practice.
        2nd ed. American Physical Therapy Association, Virginia2001
        • Ansari N.N.
        • Naghdi S.
        • Arab T.K.
        • Jalaie S.
        The interrater and intrarater reliability of the Modified Ashworth Scale in the assessment of muscle spasticity: limb and muscle group effect.
        NeuroRehabilitation. 2008; 23: 231-237
        • Erdfelder E.
        • Faul F.
        • Buchner A.
        GPOWER: a general power analysis program.
        Behav Res Methods Instr Comput. 1996; 28: 1-11
        • Lu T.W.
        • Chien H.L.
        • Chen H.L.
        Joint loading in the lower extremities during elliptical exercise.
        Med Sci Sports Exerc. 2007; 39: 1651-1658
        • Dempster W.T.
        • Gabel W.C.
        • Felts W.J.L.
        The anthropometry of the manual work space for the seated subject.
        Am J Phys Anthropol. 1959; 17: 289-317
        • Hsieh H.-J.
        • Lu T.-W.
        • Chen S.-C.
        • Chang C.-M.
        • Hung C.
        A new device for in situ static and dynamic calibration of force platforms.
        Gait Posture. 2011; 33: 701-705
        • Huang S.-C.
        • Lu T.-W.
        • Chen H.-L.
        • Wang T.-M.
        • Chou L.-S.
        Age and height effects on the center of mass and center of pressure inclination angles during obstacle-crossing.
        Med Eng Phys. 2008; 30: 968-975
        • Hsu W.-C.
        • Wang T.-M.
        • Liu M.-W.
        • Chang C.-F.
        • Chen H.-L.
        • Lu T.-W.
        Control of body’s center of mass motion during level walking and obstacle-crossing in older patients with knee osteoarthritis.
        J Med. 2010; 26: 229-237
        • Woltring H.J.
        A fortran package for generalized, cross-validatory spline smoothing and differentiation.
        Adv Eng Softw Workst. 1986; 8: 104-113
        • Winter D.A.
        Biomechanics and motor control of human movement.
        2nd ed. Wiley, New York1990
        • Hughes M.A.
        • Weiner D.K.
        • Schenkman M.L.
        • Long R.M.
        • Studenski S.A.
        Chair rise strategies in the elderly.
        Clin Biomech. 1994; 9: 187-192
        • Ikeda E.R.
        • Schenkman M.L.
        • Riley P.O.
        • Hodge W.A.
        Influence of age on dynamics of rising from a chair.
        Phys Ther. 1991; 71: 473-481
        • Pai Y.-C.
        • Naughton B.J.
        • Chang R.W.
        • Rogers M.W.
        Control of body centre of mass momentum during sit-to-stand among young and elderly adults.
        Gait Posture. 1994; 2: 109-116