Int J Sports Med 1983; 04(3): 177-183
DOI: 10.1055/s-2008-1026031
© Georg Thieme Verlag Stuttgart · New York

Adaptive Response in Human Skeletal Muscle Subjected to Prolonged Eccentric Training

J. Fridén, J. Seger, M. Sjöström, B. Ekblom
  • Departments of Anatomy and Neurology (JF and MS), University of Umeå, S-901 87 Umeå, Sweden, and
    Department of Physiology III (JS and BE), Karolinska Institutet, Lidingövägen 1, S-114 33 Stockholm, Sweden
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Publication History

Publication Date:
14 March 2008 (online)

Abstract

The peripheral adaptation process associated with repeating eccentric training over a longer period of time was studied in m. vastus lateralis of eleven healthy males aged 24 ± 4 years. The maximal dynamic concentric muscle strength was only slightly improved after 8 weeks of training. However, eccentric work capacity was dramatically increased (375%). A maximal eccentric stint immediately after fulfilled 8 weeks of training caused a selective glycogen depletion from the type 2B fibers. An increased number of type 2C fibers was observed. The ultrastructural analysis showed an essentially well-preserved fine structure. Volume density of mitochondria was somewhat higher in all fiber types after training. Z-band widths were not affected by eccentric training. It is concluded that skeletal musculature adapts itself in a functional manner to the extreme tension demands put on them. Improved coordination and reorganization of the contractile apparatus of muscle fibers are the determining mechanisms of this adaptation.

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