Upper limb effort does not increase maximal voluntary muscle activation in individuals with incomplete spinal cord injury.
OBJECTIVE
To determine the effect of upper limb effort on maximal lower limb muscle activation in individuals with incomplete spinal cord injury.


METHODS
Fifteen individuals with incomplete spinal cord injury performed recumbent stepping using different combinations of upper and lower limb efforts.


RESULTS
There was no significant difference in active lower limb electromyography amplitudes regardless of whether the upper limbs were resting or exerting maximal effort. Upper limb effort increased passive lower limb muscle activation and likewise, lower limb effort increased passive upper limb muscle activation.


CONCLUSIONS
Upper limb effort did not increase lower limb muscle activation during active lower limb effort in individuals with incomplete spinal cord injury during recumbent stepping. This suggests that individuals with incomplete spinal cord injury cannot recruit additional lower limb motor units using maximal volitional effort of their upper limbs.


CONCLUSIONS
Understanding how upper limb effort and movement influences lower limb muscle activation patterns in incomplete spinal cord injury patients has implications for prescribing therapies for lower limb rehabilitation.
Huang
Helen J
HJ
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA. helen.huang@colorado.edu
Ferris
Daniel P
DP
D000328:Adult; D000368:Aged; D003627:Data Interpretation, Statistical; D004576:Electromyography; D005260:Female; D006801:Humans; D007596:Joints / Q000033:anatomy & histology / Q000502:physiology; D007700:Kinetics; D008124:Locomotion / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D005082:Physical Exertion / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D034941:Upper Extremity / Q000503:physiopathology*; D055815:Young Adult
J Neurophysiol. 2008 Jun;99(6):2946-55
18450579
Brain Res. 1993 Feb 12;603(1):96-101
8453480
J Neurophysiol. 2007 Sep;98(3):1810-4
17615121
Arch Neurol. 1961 Feb;4:165-72
13691977
J Appl Physiol (1985). 2003 Jan;94(1):171-8
12391080
J Appl Physiol (1985). 1991 Jan;70(1):306-16
2010386
Neurosci Lett. 2007 Apr 12;416(2):138-43
17331647
Neuroimage. 2007 Mar;35(1):16-27
17223576
Biofizika. 1966;11(4):659-66
6000625
J Appl Physiol (1985). 2003 Mar;94(3):966-74
12433847
Neuroscientist. 2004 Aug;10(4):347-61
15271262
J Neurophysiol. 2004 Apr;91(4):1516-23
14657191
Paraplegia. 1994 Aug;32(8):540-53
7970859
Exerc Sport Sci Rev. 2006 Jul;34(3):113-20
16829738
Phys Ther. 2000 Jul;80(7):688-700
10869131
J Neurol Sci. 1992 May;109(1):49-55
1517764
Exp Brain Res. 2008 May;187(1):129-38
18251017
Med Sci Sports Exerc. 2009 Sep;41(9):1778-89
19657291
Exp Brain Res. 2004 Dec;159(3):382-8
15480593
Eur J Appl Physiol Occup Physiol. 1994;69(3):240-3
8001536
Jpn J Physiol. 1997 Dec;47(6):487-98
9538273
J Appl Physiol (1985). 2004 Oct;97(4):1299-308
15180979
Motor Control. 2005 Apr;9(2):144-63
15995256
Neurosci Lett. 2007 May 23;419(1):10-4
17452078
Exp Brain Res. 2006 Nov;175(3):526-35
16924489
J Neurophysiol. 2006 Feb;95(2):914-21
16251263
Behav Brain Res. 1983 Feb;7(2):165-78
6830650
J Appl Physiol Respir Environ Exerc Physiol. 1984 Jan;56(1):46-51
6693334
Brain. 2002 Dec;125(Pt 12):2626-34
12429590
Trends Neurosci. 2002 Sep;25(9):462-7
12183207