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The myofibrillar complex and fatigue: a review
1Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, 48190, USA.
Summary
Metabolites like ADP, Pi, and H+, and reactive oxygen species (ROS) can impair skeletal muscle myosin motor function, reducing muscle power. Further research is needed to clarify these effects in human muscle at physiological temperatures.
Area of Science:
- Muscle physiology
- Skeletal muscle biomechanics
- Cellular energy metabolism
Background:
- Biological movement relies on motor proteins converting chemical to mechanical energy.
- Skeletal muscle utilizes myosin II, which interacts with actin, driven by ATP hydrolysis.
- Muscle contraction is regulated by calcium ions (Ca2+).
Purpose of the Study:
- To investigate the influence of ATP-hydrolysis products and reactive oxygen species (ROS) on human skeletal muscle myofibrillar protein function.
- To clarify the effects of metabolite accumulation on muscle function at physiological temperatures.
Main Methods:
- Studies on single muscle fibers at sub-physiological temperatures have identified inhibitory effects of ADP, Pi, H+, and ROS on myosin motor function.
- Previous research utilized low temperatures, necessitating studies at more physiological conditions.
Main Results:
- Accumulation of ATP-hydrolysis products (ADP, Pi, H+) and ROS inhibits myosin motor function.
- Metabolic impairments reduce maximal Ca2+ activated force, Ca2+ sensitivity of force, and unloaded shortening velocity.
- Previous findings were based on experiments at room temperature or lower.
Conclusions:
- Metabolite and ROS accumulation can cause myofibrillar fatigue by inhibiting myosin motor function.
- The precise impact of these factors on human skeletal muscle at physiological temperatures requires further investigation.
- Understanding these mechanisms is crucial for comprehending muscle fatigue during intense activity.