ISSN:
1432-2013
Keywords:
Slow Muscle Fibers
;
Fast Muscle Fibers
;
Plasma FFA
;
Blood Lactate
;
Metabolism during Exercise
;
Fiber Recruitment
;
Fiber Types
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The glycogen depletion pattern in human muscle fibers was followed throughout the course of prolonged exercise at a work load requiring 67% of the subjects' maximal aerobic power. Biopsy samples were taken from the vastus lateralis muscle at rest and after 20, 60, 120, and 180 (or when unable to continue at the prescribed load) min of exercise. Muscle fibers were identified as fast twitch (FT) or slow twitch (ST) on the basis of myofibrillar ATPase activity. The glycogen content of muscle samples was determined biochemically. At the end of the exercise total muscle glycogen content was very low. Glycogen was also estimated in the fibers with the PAS stain. ST fibers were the first to become depleted of their glycogen but as the exercise progressed, the FT fibers were also depleted. These data may suggest a preferential utilization of ST fibers during prolonged, intense exercise, with a secondary recruitment of FT occuring as the ST fibers became depleted of their glycogen stores.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00587437
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