Abstract
A study has been made of the contractile properties of plantarflexor and dorsiflexor muscles in 25 patients with myotonic dystrophy and in the same number of closely-matched control subjects. As anticipated, the mean torques developed during maximal voluntary contraction and during the isometric twitch were significantly reduced in the patient population, as were the mean amplitudes of the respective maximum muscle compound action potentials (M-waves). There was considerable variation in weakness between patients, however, and in some there was a striking discrepancy between the results for the plantarflexor and dorsiflexor muscles. It was also found that, in both muscle groups, the mean twitch contraction times were significantly shorter in patients than in controls, but no differences could be demonstrated in relation to fatiguability and post-activation of the twitch. Some patients had great difficulty in obtaining full activation of plantarflexor motor units but there was improvement with repeated effort.
Full text
PDF![625](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/d1a833381dbf/jnnpsyc00135-0041.png)
![626](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/e01eb8a07832/jnnpsyc00135-0042.png)
![627](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/481e8f25fc22/jnnpsyc00135-0043.png)
![628](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/9e6d292b64ef/jnnpsyc00135-0044.png)
![629](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/e04fb8d0ab04/jnnpsyc00135-0045.png)
![630](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/1eaf5f84d69f/jnnpsyc00135-0046.png)
![631](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/45b0/1027481/44f32a56cd51/jnnpsyc00135-0047.png)
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Buchthal F., Schmalbruch H., Kamieniecka Z. Contraction times and fiber types in patients with progressive muscular dystrophy. Neurology. 1971 Feb;21(2):131–139. doi: 10.1212/wnl.21.2.131. [DOI] [PubMed] [Google Scholar]
- Desmedt J. E., Emeryk B. Disorder of muscle contraction processes in sex-linked (Duchenne) muscular dystrophy, with correlative electromyographic study of myopathic involvement in small hand muscles. Am J Med. 1968 Dec;45(6):853–872. doi: 10.1016/0002-9343(68)90184-8. [DOI] [PubMed] [Google Scholar]
- Fuglsang-Frederiksen A., Scheel U. Transient decrease in number of motor units after immobilisation in man. J Neurol Neurosurg Psychiatry. 1978 Oct;41(10):924–929. doi: 10.1136/jnnp.41.10.924. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hofmann W. W., Ruprecht E. O. Observations on the efficiency of dystrophic muscle in vitro. J Neurol Neurosurg Psychiatry. 1973 Aug;36(4):565–573. doi: 10.1136/jnnp.36.4.565. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LENMAN J. A. Quantitative electromyographic changes assocsiated with muscular weakness. J Neurol Neurosurg Psychiatry. 1959 Nov;22:306–310. doi: 10.1136/jnnp.22.4.306. [DOI] [PMC free article] [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]
- Marsh E., Sale D., McComas A. J., Quinlan J. Influence of joint position on ankle dorsiflexion in humans. J Appl Physiol Respir Environ Exerc Physiol. 1981 Jul;51(1):160–167. doi: 10.1152/jappl.1981.51.1.160. [DOI] [PubMed] [Google Scholar]
- McComas A. J., Campbell M. J., Sica R. E. Electrophysiological study of dystrophia myotonica. J Neurol Neurosurg Psychiatry. 1971 Apr;34(2):132–139. [PMC free article] [PubMed] [Google Scholar]
- McComas A. J., Sica R. E., Currie S. An electrophysiological study of Duchenne dystrophy. J Neurol Neurosurg Psychiatry. 1971 Aug;34(4):461–468. doi: 10.1136/jnnp.34.4.461. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McComas A. J., Thomas H. C. A study of the muscle twitch in the Duchenne type muscular dystrophy. J Neurol Sci. 1968 Sep-Oct;7(2):309–312. doi: 10.1016/0022-510x(68)90151-2. [DOI] [PubMed] [Google Scholar]
- Mussini I., Di Mauro S., Angelini C. Early ultrastructural and biochemical changes in muscle in dystrophia myotonica. J Neurol Sci. 1970 Jun;10(6):585–604. doi: 10.1016/0022-510x(70)90190-5. [DOI] [PubMed] [Google Scholar]
- Ranatunga K. W. Potentiation of the isometric twitch and mechanism of tension recruitment in mammalian skeletal muscle. Exp Neurol. 1979 Feb;63(2):266–276. doi: 10.1016/0014-4886(79)90123-7. [DOI] [PubMed] [Google Scholar]
- SANDOW A., BRUST M. Effects of activity on contractions of normal and dystrophic mouse muscles. Am J Physiol. 1962 May;202:815–820. doi: 10.1152/ajplegacy.1962.202.5.815. [DOI] [PubMed] [Google Scholar]
- Sale D. G., McComas A. J., MacDougall J. D., Upton A. R. Neuromuscular adaptation in human thenar muscles following strength training and immobilization. J Appl Physiol Respir Environ Exerc Physiol. 1982 Aug;53(2):419–424. doi: 10.1152/jappl.1982.53.2.419. [DOI] [PubMed] [Google Scholar]
- Sale D., Quinlan J., Marsh E., McComas A. J., Belanger A. Y. Influence of joint position on ankle plantarflexion in humans. J Appl Physiol Respir Environ Exerc Physiol. 1982 Jun;52(6):1636–1642. doi: 10.1152/jappl.1982.52.6.1636. [DOI] [PubMed] [Google Scholar]
- Sica R. E., McComas A. J. An electrophysiological investigation of limb-girdle and facioscapulohumeral dystrophy. J Neurol Neurosurg Psychiatry. 1971 Aug;34(4):469–474. doi: 10.1136/jnnp.34.4.469. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Takagi A., Nonaka I. Duchenne muscular dystrophy: unusual activation of single fibers in vitro. Muscle Nerve. 1981 Jan-Feb;4(1):10–15. doi: 10.1002/mus.880040104. [DOI] [PubMed] [Google Scholar]
- Takamori M., Hazama R., Tsujihata M. Active state properties of denervated and immobilized muscle: comparison with dystrophic muscle. Neurology. 1978 Jun;28(6):603–608. doi: 10.1212/wnl.28.6.603. [DOI] [PubMed] [Google Scholar]
- Wood D. S., Sorenson M. M., Eastwood A. B., Charash W. E., Reuben J. P. Duchenne dystrophy: abnormal generation of tension and Ca++ regulation in single skinned fibers. Neurology. 1978 May;28(5):447–457. doi: 10.1212/wnl.28.5.447. [DOI] [PubMed] [Google Scholar]