Diminished fatigue at reduced muscle length in human skeletal muscle.
Understanding muscle fatigue properties at different muscle lengths is essential to improve electrical stimulation applications in which impaired muscle is activated to produce function or to serve as an orthotic assist. This study examined the effects of muscle length on fatigue in human quadriceps muscle. Twelve healthy subjects were tested at short and long muscle lengths (15 degrees and 90 degrees of knee flexion, respectively) before and after a fatigue-producing protocol using low-, high-, and variable-frequency testing trains. Greater fatigue was observed at the longer muscle length, supporting the notion that fatigue is largely dependent upon metabolic factors. Fatigue, however, was characterized by greater attenuation of low- than high-frequency responses (i.e., low-frequency fatigue, LFF) at the long length. This observation, accompanied by the fact that variable-frequency trains produced greater augmentations in force production than comparable low-frequency trains at the longer length, suggests that excitation-contraction coupling impairment is also a contributing factor to fatigue and plays a greater role at the more fatigue-susceptible longer muscle length.
Lee
Samuel C K
SC
Department of Physical Therapy, University of Delaware, Newark, Delaware, USA.
Braim
Anthony
A
Becker
Cara N
CN
Prosser
Laura A
LA
Tokay
Ann M
AM
Binder-Macleod
Stuart A
SA
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology; D013314:Stress, Mechanical
Clin Physiol. 2000 Nov;20(6):474-82
11100395
J Physiol. 1996 Mar 15;491 ( Pt 3):813-24
8815213
J Physiol. 1968 Dec;199(2):241-52
5723511
Acta Orthop Scand. 1972;43(2):138-47
5079748
J Physiol. 1973 Nov;234(3):723-48
4148752
J Neurophysiol. 1980 May;43(5):1206-20
7373362
J Physiol. 1980 Jun;303:1-8
6968824
J Appl Physiol Respir Environ Exerc Physiol. 1981 Jul;51(1):160-7
7263411
Ciba Found Symp. 1981;82:178-96
6913470
J Gen Physiol. 1981 Sep;78(3):295-311
7328404
J Physiol. 1985 May;362:205-13
4020687
Muscle Nerve. 1984 Nov-Dec;7(9):691-9
6100456
J Physiol. 1989 Mar;410:351-66
2529371
J Appl Physiol (1985). 1992 Jul;73(1):160-5
1506363
J Physiol. 1992 Apr;449:85-108
1522528
J Neurophysiol. 1992 Oct;68(4):1068-78
1432068
Med Sci Sports Exerc. 1993 Jul;25(7):783-9
8350699
J Appl Physiol (1985). 1993 Jul;75(1):382-8
8397180
Acta Physiol Scand. 1996 Mar;156(3):169-81
8729677
Acta Physiol Scand. 1996 Mar;156(3):193-202
8729679
Acta Physiol Scand. 1996 Mar;156(3):387-96
8729699
J Appl Physiol (1985). 1996 Jun;80(6):2051-9
8806913
J Appl Physiol (1985). 1996 Aug;81(2):731-7
8872640
J Appl Physiol (1985). 1997 Feb;82(2):447-52
9049723
Arch Phys Med Rehabil. 1997 Oct;78(10):1129-37
9339165
J Neurophysiol. 1998 Apr;79(4):1858-68
9535953
Phys Ther. 1999 Aug;79(8):738-48
10440660
Biochim Biophys Acta. 1964 Jul 29;88:215-7
14203153
J Exp Biol. 2005 Jan;208(Pt 1):55-63
15601877
J Physiol. 1994 Jul 15;478 ( Pt 2):331-9
7965848
J Appl Physiol (1985). 1994 Sep;77(3):1148-54
7836116
Med Sci Sports Exerc. 2002 Nov;34(11):1738-43
12439077