title: Muscle synergies in preparation to a step made with obstacle in elderly individuals.
abstract: BACKGROUND
  To evaluate if multi-muscle synergies are comprised of flexible combinations of a small number of postural muscles to stabilize the center of pressure (COP) shift during preparation to making a step in the elderly (self-paced level stepping vs. obstacle crossing stepping).
  
  
  METHODS
  Electromyography (EMG) signals of leg and trunk muscles were recorded. Linear combination of integrated indices of muscle activity (M-modes) and their relationship to changes in the COP shift in the anterior-posterior (AP) direction were first determined. Uncontrolled manifold (UCM) analysis was performed to determine the extent to which variance of the M-modes acted to produce a consistent change in the COP displacement.
  
  
  RESULTS
  The elderly were capable of stabilizing the COPAP coordinate based on co-varied involvement of the M-modes. The synergy index (∆V) changes in the elderly emerged later (100 ms prior to t0) and its magnitude was smaller as compared to that reported in younger persons.
  
  
  CONCLUSIONS
  Our study reveals that aging is associated with a preserved ability to explore the flexibility of the M-mode compositions but a decrease ability to use multi-M-mode synergies following a predictable perturbation.
authors: Tianjin Key Lab of Exercise Physiology and Sports Medicine, Department of Health and Exercise Science, Tianjin University of Sport, 51 Weijin South Street, Hexi District, Tianjin, 300381, China. yunwang70@hotmail.com.
authors: Yun
authors: Y
authors: Wang
authors: Institute of Sports and Health Science, 3-10-31, Kagamiyama, Higashi-hiroshima, Hiroshima, 739-0046, Japan. kazuwp@hiroshima-u.ac.jp.
authors: Kazuhiko
authors: K
authors: Watanabe
authors: Department of Rehabilitation Science, Faculty of Health Sciences, Hokkaido University, N12-W5, Kita-ku, Sapporo, 060-0826, Japan. ask-chu@hs.hokadai.ac.jp.
authors: Tadayoshi
authors: T
authors: Asaka
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D016138:Walking / Q000502:physiology*
references: Gait Posture. 2003 Dec;18(3):125-33
references: 14667945
references: Exp Brain Res. 2011 Jul;212(1):47-63
references: 21537967
references: Gait Posture. 2005 Dec;22(4):356-61
references: 16274919
references: Brain Res Bull. 2008 May 15;76(1-2):16-25
references: 18395606
references: J Neurophysiol. 2011 May;105(5):2275-88
references: 21389305
references: Eur J Appl Physiol. 2014 Dec;114(12):2561-9
references: 25118841
references: Exp Brain Res. 1999 Jun;126(3):289-306
references: 10382616
references: Clin Neurophysiol. 2013 Aug;124(8):1628-37
references: 23601702
references: J Neurophysiol. 1996 Jun;75(6):2334-43
references: 8793746
references: Res Sports Med. 2003 Dec 1;11(4):219-34
references: 21851316
references: Exp Brain Res. 2014 Apr;232(4):1127-36
references: 24449006
references: Arch Gerontol Geriatr. 2011 Nov-Dec;53(3):338-43
references: 21310498
references: Exp Brain Res. 2003 Oct;152(3):281-92
references: 12904934
references: Gait Posture. 2006 Oct;24(2):203-10
references: 16213140
references: Am J Prev Med. 2003 Oct;25(3 Suppl 2):157-63
references: 14552940
references: Int J Psychophysiol. 1996 Apr-May;22(1-2):117-22
references: 8799774
references: J Electromyogr Kinesiol. 2012 Feb;22(1):110-6
references: 22142740
references: Age Ageing. 2006 Sep;35 Suppl 2:ii7-ii11
references: 16926210
references: Age (Dordr). 2014 Jun;36(3):9621
references: 24532389
references: Gait Posture. 2004 Jun;19(3):279-87
references: 15125917
references: Gait Posture. 2008 Jan;27(1):172-5
references: 17416525
references: Clin Neurophysiol. 2006 Jan;117(1):41-56
references: 16364687
references: Exp Brain Res. 2008 Jan;184(3):323-38
references: 17724582
references: Br Med J. 1977 Jan 29;1(6056):261-4
references: 837061
references: Exp Brain Res. 2005 Nov;167(2):196-210
references: 16034579
references: Neurophysiol Clin. 2008 Dec;38(6):467-78
references: 19026966
references: Gait Posture. 1998 Aug 1;8(1):8-14
references: 10200394
references: Exp Brain Res. 2013 May;226(4):463-72
references: 23571498
references: Med Eng Phys. 2008 Oct;30(8):968-75
references: 18243037
references: Int J Neurosci. 1983;18(1-2):1-9
references: 6840974
references: J Neurophysiol. 2004 Jan;91(1):489-501
references: 12944541