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Effects of fatigue and training on sarcoplasmic reticulum Ca(2+) regulation in human skeletal muscle
journal contribution
posted on 2002-03-01, 00:00 authored by J L Li, X N Wang, Steve FraserSteve Fraser, M F Carey, T V Wrigley, M J McKennaLittle is known about fatigue and training effects on sarcoplasmic reticulum (SR) function in human muscle, and we therefore investigated this in eight untrained controls (UT), eight endurance-trained (ET), and eight resistance-trained athletes (RT). Muscle biopsies (vastus lateralis) taken at rest and after 50 maximal quadriceps contractions (180 degrees/s, 0.5 Hz) were analyzed for fiber composition, metabolites and maximal SR Ca(2+) release, Ca(2+) uptake, and Ca(2+)-ATPase activity. Fatigue reduced (P < 0.05) Ca(2+) release (42.1 +/- 3.8%, 43.4 +/- 3.9%, 31.3 +/- 6.1%), Ca(2+) uptake (43.0 +/- 5.2%, 34.1 +/- 4.6%, 28.4 +/- 2.8%), and Ca(2+)-ATPase activity (38.6 +/- 4.2%, 48.5 +/- 5.7%, 29.6 +/- 5.0%), in UT, RT, and ET, respectively. These decreases were correlated with fatigability and with type II fiber proportion (P < 0.05). Resting SR measures were correlated with type II proportion (r > or = 0.51, P < 0.05). ET had lower resting Ca(2+) release, Ca(2+) uptake, and Ca(2+)-ATPase (P < 0.05) than UT and RT (P < 0.05), probably because of their lower type II proportion; only minor effects were found in RT. Thus SR function is markedly depressed with fatigue in controls and in athletes, is dependent on fiber type, and appears to be minimally affected by chronic training status.
History
Journal
Journal of applied physiologyVolume
92Issue
3Pagination
912 - 922Publisher
American Physiological SocietyLocation
Bethesda, Md.Publisher DOI
ISSN
8750-7587Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2002, American Physiological SocietyUsage metrics
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No categories selectedKeywords
AdultCalciumCalcium-Transporting ATPasesHumansMuscle FatigueMuscle Fibers, Fast-TwitchMuscle Fibers, Slow-TwitchMuscle, SkeletalPhysical Education and TrainingPhysical EnduranceReference ValuesSarcoplasmic ReticulumWeight LiftingScience & TechnologyLife Sciences & BiomedicinePhysiologySport Sciencescalcium releasecalcium uptakecalcium-ATPasefiber typeexerciseLOW-FREQUENCY FATIGUECALCIUM-UPTAKECELLULAR MECHANISMSINTRACELLULAR CA2+CA-2+ RELEASEFIBERSFORCERATRELAXATION
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