Fatigue

This volume describes the current state of our knowledge on the neurobiology of muscle fatigue, with consideration also given to selected integrative cardiorespiratory mechanisms. Our charge to the authors of the various chapters was twofold: to provide a systematic review of the topic that could serve as a balanced reference text for practicing health-care professionals, teaching faculty, and pre-and postdoctoral trainees in the biomedi cal sciences; and to stimulate further experimental and theoretical work on neurobiology. Key issues are addressed in nine interrelated areas: fatigue of single muscle fibers, fatigue at the neuromuscular junction, fatigue of single motor units, metabolic fatigue studied with nuclear magnetic resonance, fatigue of the segmental motor system, fatigue involving suprasegmental mechanisms, the task dependency of fatigue mechanisms, integrative (largely cardiorespiratory) systems issues, and fatigue of adapted systems (due to aging, under-and overuse, and pathophysiology). The product is a volume that provides compre of processes that operate from the forebrain to the contractile proteins.

Zusammenfassung
Proceedings based in part on the symposium on Neural and Neuromuscular Aspects of Muscular Fatigue held in Miami, Florida, November 10-13, 1994

Inhalt
Looking Back.- The Scientific Contributions of Brenda Bigland-Ritchie.- Section I: Fatigue of Single Muscle Fibers.- 1. Myofibrillar Fatigue versus Failure of Activation.- 2. Mechanisms of Excitation-Contraction Coupling Relevant to Skeletal Muscle Fatigue.- 3. The Role of Intracellular Acidosis in Muscle Fatigue.- 4. Role of Interstitial Potassium.- Section II: Fatigue at the Neuromuscular Junction.- 5. Fatigue at the Neuromuscular Junction: Branch Point vs. Presynaptic vs. Postsynaptic Mechanisms.- 6. The Role of the Sarcolemma Action Potential in Fatigue.- 7. Single Fiber Electromyography in Studies of Neuromuscular Function.- Section III: Fatigue of Single Motor Units.- 8. Intrinsic Properties of Motoneurons: Implications for Muscle Fatigue.- 9. Neuromuscular Frequency Coding and Fatigue.- 10. Human Motor Units Studied by Spike-Triggered Averaging and Intraneural Motor Axon Stimulation.- 11. Human Motor Units Studied by Intramuscular Microstimulation.- Section IV: Fatigue Studied with NMR Techniques.- 12. Bioenergetics and Muscle Cell Types.- 13. Metabolic Correlates of Fatigue from Different Types of Exercise in Man.- 14. Mechanisms of Human Muscle Fatigue: Quantitating the Contribution of Metabolic Factors and Activation Impairment.- 15. Emerging Opportunities with NMR.- Section V: The Case for Segmental Motor Mechanisms.- 16. Variable-Frequency Stimulation Patterns for the Optimization of Force during Muscle Fatigue: Muscle Wisdom and the Catch-like Property.- 17. Overview: Potential Role of Segmental Motor Circuitry in Muscle Fatigue.- 18. The Fusimotor System: Its Role in Fatigue.- 19. Role of Muscle Afferents in the Inhibition of Motoneurons during Fatigue.- Section VI: The Case for Central Fatigue.- 20. Central Fatigue: Critical Issues, Quantification and Practical Implications.- 21. Single-Trial Readiness Potentials and Fatigue.- 22. The Senses of Effort and Force during Fatiguing Contractions.- 23. Tryptophan, 5-Hydroxytryptamine and a Possible Explanation for Central Fatigue.- Section VII: Task Dependency of Fatigue Mechanisms.- 24. The Significance of Motor Unit Variability in Sustaining Mechanical Output of Muscle.- 25. Intramuscular Pressures for Monitoring Different Tasks and Muscle Conditions.- 26. Task-Dependent Nature of Fatigue in Single Motor Units.- 27. Task-Dependent Factors in Fatigue of Human Voluntary Contractions.- Section VIII: Integrative Systems Issues.- 28. Fatigue and the Design of the Respiratory System.- 29. An Integrative View of Limitations to Muscular Performance.- 30. Respiratory Muscle Fatigue.- 31. Fatigue of Jaw Muscles and Speech Mechanisms.- Section IX: Fatigue of Adapted Systems: Overuse, Underuse, and Pathophysiology.- 32. Fatigue in Adapted Systems: Overuse and Underuse Paradigms.- 33. Associations between Muscle Soreness, Damage, and Fatigue.- 34. Muscle Fatigue in Old Animals: Unique Aspects of Fatigue in Elderly Humans.- 35. Historical Perspective: A Framework for Interpreting Pathobiological Ideas on Human Muscle Fatigue.- 36. Fatigue Brought on by Malfunction of the Central and Peripheral Nervous Systems.- Epilogue.- 37. Neurobiology of Muscle Fatigue: Advances and Issues.- Contributors.