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Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Do multiple ionic interactions contribute to skeletal muscle fatigue?
1Institute of Sport and Recreation Research New Zealand, Faculty of Health and Environmental Sciences, AUT University, Auckland 1020, New Zealand. simeon.cairns@aut.ac.nz
The Journal of Physiology
|July 2, 2008
Summary
During intense exercise, potassium shifts contribute to muscle fatigue by altering ion gradients. However, moderate potassium increases can enhance performance and blood flow, with other ions and metabolites interacting with these effects.
Area of Science:
- Muscle physiology
- Exercise science
- Cellular biophysics
Background:
- Intense exercise causes simultaneous ion concentration changes in skeletal muscle compartments.
- Understanding these multiple ionic shifts together is crucial for explaining functional effects.
Purpose of the Study:
- To investigate the role of ion gradients, particularly potassium, in skeletal muscle fatigue during intense exercise.
- To explore interactions between different ions and metabolites in modulating muscle force and performance.
Main Methods:
- The study reviews existing literature and theoretical models on ion dynamics in skeletal muscle.
- It analyzes the effects of varying extracellular potassium concentrations ([K(+)](o)) on muscle force and blood flow.
- It considers the interplay of sodium (Na(+)), calcium (Ca(2+)), chloride (Cl(-)), and hydrogen ions (H(+)) with potassium effects.
Main Results:
- Diminished transsarcolemmal K(+) gradient can reduce maximal force, suggesting K(+) contributes to fatigue, but requires large shifts.
- Moderate increases in extracellular [K(+)](o) can potentiate contractions, enhance blood flow, and aid exercise performance.
- Other ion gradients (Na(+), Ca(2+), Cl(-), H(+)) interact with K(+) effects, influencing force production and fatigue resistance.
Conclusions:
- A rundown of the transsarcolemmal K(+) gradient is hypothesized as the dominant cellular process in high-intensity exercise fatigue.
- Interactions with other ions and metabolites modulate the detrimental effects of K(+) shifts.
- Understanding these complex ionic and metabolic interactions is key to comprehending muscle fatigue during strenuous activity.
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