Extraction of individual muscle mechanical action from endpoint force.
Most motor tasks require the simultaneous coordination of multiple muscles. That coordination is poorly understood in part because there is no noninvasive means of isolating a single muscle's contribution to the resultant endpoint force. The contribution of a single motor unit to isometric tasks can, however, be characterized using the spike-triggered averaging (STA) technique, applied to a single motor unit's spike train. We propose that a technique analogous to STA, which we call electromyogram (EMG)-weighted averaging (EWA), can be applied to surface EMGs to extract muscle mechanical action from the natural endpoint force fluctuations generated during steady isometric contraction. We demonstrate this technique on simultaneous recordings of fingertip force and surface EMG from the first dorsal interosseous (FDI) and extensor indicis (EI) of humans. The EWA direction was approximately the same across a wide range of fingertip force directions, and the average EWA direction was consistent with mechanical action direction of these muscles estimated from cadaveric and imaging data: the EWA directions were 193 +/- 2 degrees for the FDI and 71 +/- 5 degrees for the EI (95% confidence). EWA transient behavior also appears to capture temporal characteristics of muscle force fluctuations with peak force time and general waveform shape similar to that of the associated spike-triggered averages from single motor units. The EWA may provide a means of empirically characterizing the complex transformation between muscle force and endpoint force without the need for invasive electrode recordings or complex anatomical measurements of musculoskeletal geometry.
Kutch
Jason J
JJ
Applied and Interdisciplinary Mathematics, University of Michigan, Ann Arbor, Michigan, USA. kutch@usc.edu
Kuo
Arthur D
AD
Rymer
William Z
WZ
D000200:Action Potentials / Q000502:physiology; D003198:Computer Simulation; D004576:Electromyography / Q000379:methods; D005385:Fingers / Q000294:innervation; D006801:Humans; D008954:Models, Biological; D009046:Motor Neurons / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012680:Sensitivity and Specificity
J Neurophysiol. 1990 Oct;64(4):1339-46
2258751
J Neurophysiol. 2005 May;93(5):2449-59
15615827
Muscle Nerve. 2001 Sep;24(9):1113-33
11494264
J Neurophysiol. 1993 Nov;70(5):2010-23
8294967
J Neurophysiol. 2000 Jan;83(1):441-52
10634886
J Physiol. 1991 Jan;432:381-99
1886060
Muscle Nerve. 1989 Jul;12(7):556-67
2779604
J Neurophysiol. 2004 Nov;92(5):2878-86
15201310
Science. 1981 Nov 20;214(4523):933-6
7302570
Muscle Nerve. 1990 Jun;13(6):545-50
2366827
J Electromyogr Kinesiol. 2003 Feb;13(1):37-47
12488085
Muscle Nerve. 2001 Jul;24(7):952-62
11410924
J Comput Neurosci. 2007 Jun;22(3):347-61
17377834
Brain Res. 1972 May 12;40(1):187-92
5033795
J Appl Physiol (1985). 2005 Jan;98(1):120-31
15377649
J Neurophysiol. 2006 Sep;96(3):1646-57
16899649
J Neurophysiol. 1993 Dec;70(6):2470-88
8120594
J Biomech. 2000 Dec;33(12):1601-9
11006384
J Physiol. 1973 Jan;228(2):285-306
4687100
J Neurophysiol. 1991 Dec;66(6):2072-83
1812237
J Neurol Neurosurg Psychiatry. 1949 May;12(2):124-8
18127082
J Neurophysiol. 2007 Sep;98(3):1581-90
17615125
J Appl Physiol (1985). 2007 Mar;102(3):1193-201
17068220
Exp Neurol. 1982 Nov;78(2):360-8
7140904
Clin Biomech (Bristol, Avon). 2006 May;21(4):361-9
16406192
J Neurophysiol. 2002 Jul;88(1):265-76
12091552
Exp Neurol. 1984 Sep;85(3):631-50
6468581
J Neurophysiol. 1977 Nov;40(6):1432-43
925737
Muscle Nerve. 1986 Jan;9(1):78-83
3951484
Exp Brain Res. 1991;85(2):271-80
1893980
J Neurophysiol. 1993 Jun;69(6):2108-15
8350134
J Neurophysiol. 2001 Nov;86(5):2144-58
11698507
J Neurosci Methods. 2003 Jun 30;126(2):155-64
12814840
Exp Brain Res. 1991;85(2):257-70
1893979
J Biomech. 1983;16(6):419-25
6619158
J Neurophysiol. 1990 Oct;64(4):1331-8
2258750
J Neurosci. 1998 Oct 15;18(20):8402-16
9763483
J Neurophysiol. 1991 Jun;65(6):1509-16
1875259
Muscle Nerve. 1997 Jul;20(7):788-99
9179150
J Neurophysiol. 2001 Nov;86(5):2266-75
11698517
J Neurol Neurosurg Psychiatry. 1974 Jun;37(6):670-6
4844134
J Neurophysiol. 2006 Jan;95(1):493-504
16251262
J Neurophysiol. 1986 May;55(5):1017-29
3711964
J Neurophysiol. 2004 Jun;91(6):2515-23
14724266
Acta Physiol Scand. 1970 Aug;79(4):435-52
5472111
J Oral Rehabil. 2006 Oct;33(10):729-40
16938101
J Neurophysiol. 1999 Jan;81(1):319-33
9914292
J Neurophysiol. 2008 Nov;100(5):2455-71
18799603
Ann Biomed Eng. 2004 Jul;32(7):1007-15
15298438
J Biomech. 2001 Jun;34(6):791-7
11470117
J Neurophysiol. 1990 Oct;64(4):1347-51
2258752
J Appl Physiol (1985). 1994 Dec;77(6):2648-58
7896604
Arch Physiol Biochem. 1999 Oct;107(4):292-311
10779826
J Physiol. 1991 Jan;432:355-80
1886059
J Appl Physiol (1985). 2004 Apr;96(4):1486-95
15016793
Exp Brain Res. 1988;71(2):377-87
3169170
Surg Radiol Anat. 1986;8(1):19-28
3088742
Biol Cybern. 1992;67(2):143-53
1627684
Ann Biomed Eng. 2007 Sep;35(9):1521-31
17530407
IEEE Trans Biomed Eng. 2007 Jun;54(6 Pt 2):1161-6
17549909
Muscle Nerve. 1995 Oct;18(10):1101-14
7659104
J Neurophysiol. 2000 Jul;84(1):358-66
10899210
J Neurophysiol. 1996 Jun;75(6):2509-19
8793760
Electroencephalogr Clin Neurophysiol. 1994 Apr;93(2):100-5
7512915
J Neurophysiol. 1993 Jan;69(1):282-5
8433132
Neural Comput. 2002 Jun;14(6):1233-60
12020444