Document Detail

Changes in calpain activity, muscle structure, and function after eccentric exercise.
MedLine Citation:
PMID:  20010126     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The aim of this study was to investigate changes in muscle function, muscle structure, and calpain activity after high-force eccentric exercise. METHODS: Eleven healthy males performed 300 maximal voluntary eccentric actions with knee extensors in one leg. Maximal force-generating capacity was measured before exercise and regularly during the next 7 d. Biopsies from musculus vastus lateralis were taken in both control and exercised legs 0.5, 4, 8, 24, 96, and 168 h after exercise for evaluation of myofibrillar structure, extracellular matrix proteins, and calpain activity. RESULTS: In the exercised leg, peak torque was reduced by 47 +/- 5% during exercise and was still 22 +/- 5% lower than baseline 4 d after the exercise. Calpain activity was three times higher in the exercised leg compared with the control leg 30 min after exercise. Myofibrillar disruptions were observed in 36 +/- 6% of all fibers in exercised muscle and in 2 +/- 1% of fibers in control muscle. The individual reductions in peak torque correlated with the proportion of fibers with myofibrillar disruptions (r = 0.89). The increase in calpain activity was not correlated to the proportion of fibers with myofibrillar disruptions. Nevertheless, the characteristics of the myofibrillar disruptions mimicked calpain-mediated degradation of myofibrils. Tenascin-C and the N-terminal propeptide of procollagen type III showed increased staining intensity on cross-sections 4-7 d after the exercise. CONCLUSIONS: Myofibrillar disruptions seem to be a main cause for the long-lasting reduction in force-generating capacity after high-force eccentric exercise. The increase in calpain activity, but the lack of a relationship between calpain activity and the amount of muscle damage, suggests multiple roles of calpain in the damage and repair process.
Truls Raastad; Simen Gylterud Owe; G?ran Paulsen; Deborah Enns; Kristian Overgaard; Regina Crameri; Steinar Kiil; Angelo Belcastro; Linda Bergersen; Jostein Hall?n
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  42     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-17     Completed Date:  2010-03-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  86-95     Citation Subset:  IM; S    
Norwegian School of Sport Sciences, Oslo, Norway.
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MeSH Terms
Analysis of Variance
Calpain / metabolism*
Exercise / physiology*
Leg / physiology
Muscle Contraction / physiology
Muscle Fatigue / physiology
Muscle, Skeletal / anatomy & histology*,  physiology*
Myofibrils / physiology
Reg. No./Substance:
EC 3.4.22.-/Calpain

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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