Muscle fatigue: what, why and how it influences muscle function

Area of Science:

• Exercise Physiology
• Muscle Physiology
• Motor Control

Background:

• Muscle fatigue arises from diverse physiological impairments, including metabolite accumulation and altered motor commands.
• No single mechanism explains all muscle fatigue; causes are task-dependent.
• Muscle fatigue is typically measured as reduced maximal force or power, allowing sustained submaximal contractions.

Purpose of the Study:

• To review experimental approaches identifying mechanisms limiting task failure.
• To differentiate between causes of muscle fatigue and factors limiting task performance duration.
• To provide insights into rate-limiting adjustments constraining muscle function during fatiguing contractions.

Main Methods:

• Review of experimental approaches focusing on task-failure mechanisms.
• Comparison of tasks, individuals, and interventions using a task-failure framework.
• Analysis of rate-limiting adjustments during fatiguing contractions.

Main Results:

• Muscle fatigue mechanisms are highly specific to the performed task.
• Task duration may be limited by factors other than fatigue in principal muscles.
• The task-failure approach offers a framework to understand performance limitations.

Conclusions:

• Understanding task-failure mechanisms is crucial for identifying performance limits.
• Task-specific analyses provide deeper insights into muscle function constraints.
• Future research should leverage task-failure approaches to elucidate fatigue.