Calcium exchange hypothesis of skeletal muscle fatigue: a brief review.
Skeletal muscle fatigue is often associated with diminished athletic performance and work productivity as well as increased susceptibility to injury. The exact cause of muscle fatigue probably involves a number of factors which influence force production in a manner dependent on muscle fiber type and activation pattern. However, a growing body of evidence implicates alterations in intracellular Ca2+ exchange as a major role in the fatigue process. These changes are thought to occur secondary to reductions in the rates of Ca2+ uptake and release by the sarcoplasmic reticulum (SR). This hypothesis is based on the finding that peak myoplasmic Ca2+ concentration ([Ca2+]i) is reduced as force declines during fatigue. In addition, direct measurements of Ca2+ uptake and release show that fatiguing activity causes intrinsic alterations in the functional properties of the SR. We also propose that fatigue-induced alterations in Ca2+ exchange may be beneficial, reducing the rate of energy utilization by the muscle fiber and preventing irreversible damage to the cell.
Williams
J H
JH
Department of Human Nutrition and Foods, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, USA.
Klug
G A
GA
D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009119:Muscle Contraction; D018763:Muscle Fatigue / Q000187:drug effects / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D005230:Fatty Acids, Nonesterified; D002110:Caffeine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006003:Glycogen; D000251:Adenosine Triphosphatases; D002118:Calcium