Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1979 Feb;287:33–43. doi: 10.1113/jphysiol.1979.sp012643

Motor unit organization of human medial gastrocnemius.

R A Garnett, M J O'Donovan, J A Stephens, A Taylor
PMCID: PMC1281479  PMID: 430414

Abstract

1. The properties of fifty-seven motor units in human medial gastrocnemius have been studied using controlled intramuscular microstimulation, glycogen depletion and muscle biopsy. 2. Motor units could be divided into three classes on the basis of their mechanical properties. Type S units were slow, small and fatigue resistant. Type FR units were fast, intermediate in size, and fatigue resistant. Type FF units were fast, large and fatigable. 3. Glycogen depletion of a number of type S and FF units revealed them to be composed of type 1 and type 2b muscle fibres respectively. 4. The results suggest that during slowly increasing voluntary contractions where units are recruited in order of size, type 1 and 2a muscle fibres would be employed at low force levels followed by type 2b muscle fibres in stronger contractions.

Full text

PDF
33

Images in this article

39Fig. 5
on p.39
40Fig. 6
on p.40

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BULLER A. J., DORNHORST A. C., EDWARDS R., KERR D., WHELAN R. F. Fast and slow muscles in mammals. Nature. 1959 May 30;183(4674):1516–1517. doi: 10.1038/1831516a0. [DOI] [PubMed] [Google Scholar]
  2. Bagust J., Knott S., Lewis D. M., Luck J. C., Westerman R. A. Isometric contractions of motor units in a fast twitch muscle of the cat. J Physiol. 1973 May;231(1):87–104. doi: 10.1113/jphysiol.1973.sp010221. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bagust J. Relationships between motor nerve conduction velocities and motor unit contraction characteristics in a slow twitch muscle of the cat. J Physiol. 1974 Apr;238(2):269–278. doi: 10.1113/jphysiol.1974.sp010523. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Bosley M. A., O'Donovan M. J., Stephens J. A., Taylor A., Usherwood T. P. Unit studies in normal human gastrocnemius by microstimulation, glycogen depletion, and needle biopsy (film) [proceedings]. J Physiol. 1976 Sep;260(2):11P–12P. [PubMed] [Google Scholar]
  5. Buchthal F., Schmalbruch H. Contraction times and fibre types in intact human muscle. Acta Physiol Scand. 1970 Aug;79(4):435–452. doi: 10.1111/j.1748-1716.1970.tb04744.x. [DOI] [PubMed] [Google Scholar]
  6. Burke R. E., Levine D. N., Tsairis P., Zajac F. E., 3rd Physiological types and histochemical profiles in motor units of the cat gastrocnemius. J Physiol. 1973 Nov;234(3):723–748. doi: 10.1113/jphysiol.1973.sp010369. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Burke R. E., Levine D. N., Zajac F. E., 3rd Mammalian motor units: physiological-histochemical correlation in three types in cat gastrocnemius. Science. 1971 Nov 12;174(4010):709–712. doi: 10.1126/science.174.4010.709. [DOI] [PubMed] [Google Scholar]
  8. Desmedt J. E., Godaux E. Ballistic contractions in man: characteristic recruitment pattern of single motor units of the tibialis anterior muscle. J Physiol. 1977 Jan;264(3):673–693. doi: 10.1113/jphysiol.1977.sp011689. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Haxton H. A. Absolute muscle force in the ankle flexors of man. J Physiol. 1944 Dec 15;103(3):267–273. doi: 10.1113/jphysiol.1944.sp004075. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. MCPHEDRAN A. M., WUERKER R. B., HENNEMAN E. PROPERTIES OF MOTOR UNITS IN A HETEROGENEOUS PALE MUSCLE (M. GASTROCNEMIUS) OF THE CAT. J Neurophysiol. 1965 Jan;28:85–99. doi: 10.1152/jn.1965.28.1.85. [DOI] [PubMed] [Google Scholar]
  11. Merrill E. G. A simple light-coupled stimulus isolator. J Physiol. 1972 Apr;222(2):120P–121P. [PubMed] [Google Scholar]
  12. Milner-Brown H. S., Stein R. B., Yemm R. The orderly recruitment of human motor units during voluntary isometric contractions. J Physiol. 1973 Apr;230(2):359–370. doi: 10.1113/jphysiol.1973.sp010192. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. O'Donovan M. J., Rowlerson A., Taylor A. Proceedings: Contraction characteristics and histochemistry of motor units studied in perfused human limb muscles. J Physiol. 1976 May;257(1):24P–25P. [PubMed] [Google Scholar]
  14. O'Donovan M. J., Rowlerson A., Taylor A. Proceedings: The perfused isolated human limb: an assessment of its viability. J Physiol. 1976 Mar;256(1):27P–28P. [PubMed] [Google Scholar]
  15. PADYKULA H. A., HERMAN E. The specificity of the histochemical method for adenosine triphosphatase. J Histochem Cytochem. 1955 May;3(3):170–195. doi: 10.1177/3.3.170. [DOI] [PubMed] [Google Scholar]
  16. Proske U., Waite P. M. Properties of types of motor units in the medial gastrochemius muscle of the cat. Brain Res. 1974 Feb 15;67(1):89–101. doi: 10.1016/0006-8993(74)90300-x. [DOI] [PubMed] [Google Scholar]
  17. Sica R. E., McComas A. J. Fast and slow twitch units in a human muscle. J Neurol Neurosurg Psychiatry. 1971 Apr;34(2):113–120. doi: 10.1136/jnnp.34.2.113. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Stephens J. A., Stuart D. G. The motor units of cat medial gastrocnemius: speed-size relations and their significance for the recruitment order of mortor units. Brain Res. 1975 Jun 27;91(2):177–195. doi: 10.1016/0006-8993(75)90542-9. [DOI] [PubMed] [Google Scholar]
  19. Stephens J. A., Usherwood T. P. The mechanical properties of human motor units with special reference to their fatiguability and recruitment threshold. Brain Res. 1977 Apr 8;125(1):91–97. doi: 10.1016/0006-8993(77)90361-4. [DOI] [PubMed] [Google Scholar]
  20. Taylor A., Stephens J. A. Study of human motor unit contractions by controlled intramuscular microstimulation. Brain Res. 1976 Nov 26;117(2):331–335. doi: 10.1016/0006-8993(76)90742-3. [DOI] [PubMed] [Google Scholar]
  21. Yemm R. The orderly recruitment of motor units of the masseter and temporal muscles during voluntary isometric contraction in man. J Physiol. 1977 Feb;265(1):163–174. doi: 10.1113/jphysiol.1977.sp011710. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES