Twitch contractile adaptations are not dependent on the intensity of isometric exercise in the human triceps surae

Stephen Alway, Digby G. Sale, J. Duncan MacDougall

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Ultrastructural and twitch contractile characteristics of the human triceps surae were determined in six healthy but very sedentary subjects before and after 16 weeks of isometric training at 30% maximal voluntary contraction (MVC). Following training, twitch contraction time was approximately 16% shorter, although no differences were observed in one-half relaxation time or peak twitch torque. Percent fibre type was not changed by training. The mean area of type I and type II fibres in the soleus increased by approximately 30% but only type II fibres showed an increase in area in the lateral gastrocnemius (30%). Despite such changes in fibre area the volume density of the sarcoplasmic reticulum-transverse tubular network averaged 3.2 ± 0.6% and 5.9 ± 0.9% in type I and type II fibres respectively, before and after training in the two heads of the gastrocnemius. The results indicate that contractile adaptations to isometric training at 30% MVC were limited to twitch contraction time and were not directly related to changes in percent fibre distribution or the volume of sarcoplasmic reticulum and transverse tubules in either type I or type II fibres. The data further demonstrate that substantial fibre hypertrophy is achieved by training with low-intensity contractions.

Original languageEnglish (US)
Pages (from-to)346-352
Number of pages7
JournalEuropean Journal of Applied Physiology and Occupational Physiology
Volume60
Issue number5
DOIs
StatePublished - Sep 1 1990
Externally publishedYes

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Sarcoplasmic Reticulum
Exercise
Torque
Hypertrophy

All Science Journal Classification (ASJC) codes

  • Physiology
  • Public Health, Environmental and Occupational Health

Cite this

Twitch contractile adaptations are not dependent on the intensity of isometric exercise in the human triceps surae. / Alway, Stephen; Sale, Digby G.; MacDougall, J. Duncan.

In: European Journal of Applied Physiology and Occupational Physiology, Vol. 60, No. 5, 01.09.1990, p. 346-352.

Research output: Contribution to journalArticle

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