Abstract
1. Human adductor pollicis was fatigued using intermittent trains of programmed stimulation at 1, 10, 20, 50, 100 and 1 Hz, during activity with and without circulatory occlusion, to investigate the relationships between force generation, excitation and maximal relaxation rate (MRR). 2. The relationship between force generation and excitation was markedly dependent on stimulation frequency. Force loss was greatest at low frequencies, with little reduction in excitation, but as frequency increased force was well maintained despite marked loss of excitation. 3. Changes in MRR during activity and recovery were independent of stimulation frequency. 4. Marked increases of force at 1 Hz (pre-tetanic) and 10 Hz occurred, with little reduction in excitation, during activity with and without circulatory occlusion. This may be due to post-tetanic potentiation in addition to slowing of relaxation (MRR). 5. At high frequency a 'safety factor' may thus operate to maintain force, despite obvious loss of excitation, while at low frequencies there may be marked potentiation of force, despite unchanged excitation. These mechanisms could permit resistance to fatigue with muscle function remaining optimal over a range of conditions.
Full text
PDF














Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bigland-Ritchie B., Johansson R., Lippold O. C., Smith S., Woods J. J. Changes in motoneurone firing rates during sustained maximal voluntary contractions. J Physiol. 1983 Jul;340:335–346. doi: 10.1113/jphysiol.1983.sp014765. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bigland-Ritchie B., Johansson R., Lippold O. C., Woods J. J. Contractile speed and EMG changes during fatigue of sustained maximal voluntary contractions. J Neurophysiol. 1983 Jul;50(1):313–324. doi: 10.1152/jn.1983.50.1.313. [DOI] [PubMed] [Google Scholar]
- Blinks J. R., Rüdel R., Taylor S. R. Calcium transients in isolated amphibian skeletal muscle fibres: detection with aequorin. J Physiol. 1978 Apr;277:291–323. doi: 10.1113/jphysiol.1978.sp012273. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brandt P. W., Cox R. N., Kawai M., Robinson T. Effect of cross-bridge kinetics on apparent Ca2+ sensitivity. J Gen Physiol. 1982 Jun;79(6):997–1016. doi: 10.1085/jgp.79.6.997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dawson M. J., Gadian D. G., Wilkie D. R. Mechanical relaxation rate and metabolism studied in fatiguing muscle by phosphorus nuclear magnetic resonance. J Physiol. 1980 Feb;299:465–484. doi: 10.1113/jphysiol.1980.sp013137. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edwards R. H., Griffiths R. D., Cady E. B. Topical magnetic resonance for the study of muscle metabolism in human myopathy. Clin Physiol. 1985 Apr;5(2):93–109. doi: 10.1111/j.1475-097x.1985.tb00586.x. [DOI] [PubMed] [Google Scholar]
- Edwards R. H., Hill D. K., Jones D. A., Merton P. A. Fatigue of long duration in human skeletal muscle after exercise. J Physiol. 1977 Nov;272(3):769–778. doi: 10.1113/jphysiol.1977.sp012072. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edwards R. H. Human muscle function and fatigue. Ciba Found Symp. 1981;82:1–18. doi: 10.1002/9780470715420.ch1. [DOI] [PubMed] [Google Scholar]
- Edwards R. H., Young A., Hosking G. P., Jones D. A. Human skeletal muscle function: description of tests and normal values. Clin Sci Mol Med. 1977 Mar;52(3):283–290. doi: 10.1042/cs0520283. [DOI] [PubMed] [Google Scholar]
- Fitch S., McComas A. Influence of human muscle length on fatigue. J Physiol. 1985 May;362:205–213. doi: 10.1113/jphysiol.1985.sp015671. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Harris R. C., Hultman E., Kaijser L., Nordesjö L. O. The effect of circulatory occlusion on isometric exercise capacity and energy metabolism of the quadriceps muscle in man. Scand J Clin Lab Invest. 1975 Jan;35(1):87–95. [PubMed] [Google Scholar]
- Hirano T., Takahashi K. Development of ionic channels and cell-surface antigens in the cleavage-arrested one-cell embryo of an ascidian. J Physiol. 1987 May;386:113–133. doi: 10.1113/jphysiol.1987.sp016525. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hultman E., Sjöholm H. Electromyogram, force and relaxation time during and after continuous electrical stimulation of human skeletal muscle in situ. J Physiol. 1983 Jun;339:33–40. doi: 10.1113/jphysiol.1983.sp014700. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jones D. A., Bigland-Ritchie B., Edwards R. H. Excitation frequency and muscle fatigue: mechanical responses during voluntary and stimulated contractions. Exp Neurol. 1979 May;64(2):401–413. doi: 10.1016/0014-4886(79)90279-6. [DOI] [PubMed] [Google Scholar]
- Komi P. V., Rusko H. Quantitative evaluation of mechanical and electrical changes during fatigue loading of eccentric and concentric work. Scand J Rehabil Med Suppl. 1974;3:121–126. [PubMed] [Google Scholar]
- MERTON P. A. Voluntary strength and fatigue. J Physiol. 1954 Mar 29;123(3):553–564. doi: 10.1113/jphysiol.1954.sp005070. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marsden C. D., Meadows J. C., Merton P. A. "Muscular wisdom" that minimizes fatigue during prolonged effort in man: peak rates of motoneuron discharge and slowing of discharge during fatigue. Adv Neurol. 1983;39:169–211. [PubMed] [Google Scholar]
- Mills K. R. Power spectral analysis of electromyogram and compound muscle action potential during muscle fatigue and recovery. J Physiol. 1982 May;326:401–409. doi: 10.1113/jphysiol.1982.sp014201. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stephens J. A., Taylor A. Fatigue of maintained voluntary muscle contraction in man. J Physiol. 1972 Jan;220(1):1–18. doi: 10.1113/jphysiol.1972.sp009691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wiles C. M., Edwards R. H. The effect of temperature, ischaemia and contractile activity on the relaxation rate of human muscle. Clin Physiol. 1982 Dec;2(6):485–497. doi: 10.1111/j.1475-097x.1982.tb00055.x. [DOI] [PubMed] [Google Scholar]
- Wiles C. M., Young A., Jones D. A., Edwards R. H. Relaxation rate of constituent muscle-fibre types in human quadriceps. Clin Sci (Lond) 1979 Jan;56(1):47–52. doi: 10.1042/cs0560047. [DOI] [PubMed] [Google Scholar]
