Document Detail

The effect of pedaling frequency on glycogen depletion rates in type I and type II quadriceps muscle fibers during submaximal cycling exercise.
MedLine Citation:
PMID:  1385118     Owner:  NLM     Status:  MEDLINE    
This study was conducted to determine whether the pedaling frequency of cycling at a constant metabolic cost contributes to the pattern of fiber-type glycogen depletion. On 2 separate days, eight men cycled for 30 min at approximately 85% of individual aerobic capacity at pedaling frequencies of either 50 or 100 rev.min-1. Muscle biopsy samples (vastus lateralis) were taken immediately prior to and after exercise. Individual fibers were classified as type I (slow twitch), or type II (fast twitch), using a myosin adenosine triphosphatase stain, and their glycogen content immediately prior to and after exercise quantified via microphotometry of periodic acid-Schiff stain. The 30-min exercise bout resulted in a 46% decrease in the mean optical density (D) of type I fibers during the 50 rev.min-1 condition [0.52 (0.07) to 0.28 (0.04) D units; mean (SEM)] which was not different (P > 0.05) from the 35% decrease during the 100 rev.min-1 condition [0.48 (0.04) to 0.31 (0.05) D units]. In contrast, the mean D in type II fibers decreased 49% during the 50 rev.min-1 condition [0.53 (0.06) to 0.27 (0.04) units]. This decrease was greater (P < 0.05) than the 33% decrease observed in the 100 rev.min-1 condition [0.48 (0.04) to 0.32 (0.06) units). In conclusion, cycling at the same metabolic cost at 50 rather than 100 rev.min-1 results in greater type II fiber glycogen depletion. This is attributed to the increased muscle force required to meet the higher resistance per cycle at the lower pedal frequency.(ABSTRACT TRUNCATED AT 250 WORDS)
L E Ahlquist; D R Bassett; R Sufit; F J Nagle; D P Thomas
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of applied physiology and occupational physiology     Volume:  65     ISSN:  0301-5548     ISO Abbreviation:  Eur J Appl Physiol Occup Physiol     Publication Date:  1992  
Date Detail:
Created Date:  1992-12-14     Completed Date:  1992-12-14     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0410266     Medline TA:  Eur J Appl Physiol Occup Physiol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  360-4     Citation Subset:  IM; S    
Biodynamics Laboratory, University of Wisconsin, Madison 53706.
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MeSH Terms
Exercise / physiology*
Exercise Test
Glycogen / metabolism*
Muscles / cytology,  metabolism,  physiology*
Staining and Labeling
Reg. No./Substance:

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