Adaptations in skeletal muscle following strength training

D. L. Costill, E. F. Coyle, W. F. Fink, G. R. Lesmes, F. A. Witzmann

Research output: Contribution to journalArticle

204 Scopus citations


Five men were studied before and after 7 wk of isokinetic strength training to determine its effects on muscle enzyme activities and fiber composition. One of the subject's legs was trained using 10 repeated 6-s maximal work bouts, while the other leg performed repeated 30-s maximal knee extension exercise. The total work accomplished by each leg was constant. Training 4 times/wk achieved similar gains in peak torque for both legs at the training velocity (3.14 rad/s) and at slower speeds. Fatigability of the knee extensor muscles, as measured by a 60-s exercise test, was similar in both legs after training. Biopsy specimens showed significant changes in the % of the muscle area composed of type I and IIa fibers as a result of both strength training programs. In terms of muscle enzymes, only the 30 s exercise program resulted in elevated glycolytic, ATP-CP and mitochondrial activities. Despite these changes, none of the parameters measured were found to be related to the gains in either muscle strength or fatigability during maximal isokinetic contractions.

Original languageEnglish (US)
Pages (from-to)96-99
Number of pages4
JournalUnknown Journal
Issue number1
StatePublished - 1979

ASJC Scopus subject areas

  • Physiology
  • Endocrinology

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