Central fatigue theory and endurance exercise: Toward an interoceptive model

Area of Science:

• Neuroscience
• Exercise Physiology
• Cognitive Science

Background:

• Central fatigue during exercise is complex, involving sensory and motivational factors.
• The neural underpinnings of exercise-induced fatigue are not fully understood.
• Interoception plays a crucial role in bodily awareness and decision-making.

Purpose of the Study:

• To propose a neurocognitive model of exercise-induced central fatigue.
• To elucidate the roles of interoception and motivation in perceived fatigue.
• To map the neural pathways involved in fatigue perception and decision-making during exercise.

Main Methods:

• A neurocognitive model integrating interoception, motivation, and brain function is proposed.
• Key brain regions discussed include the dorsolateral (DL) prefrontal cortex (PFC), anterior insula cortex (AIC), anterior cingulate cortex (ACC), and ventromedial (VM)PFC.
• Involvement of neuromodulatory systems, including dopamine (DA) and norepinephrine (NE), is considered.

Main Results:

• The model posits that the DL-PFC predicts sensory feedback, compared against actual feedback by the AIC.
• This comparison generates an awareness state influencing decisions made by the LPFC, modulated by DA and NE systems.
• Perceived fatigue arises when the ACC and VMPFC signal that rewards are insufficient for the perceived cost, leading to tonic NE activity.

Conclusions:

• Exercise-induced fatigue perception is a result of integrated sensory, cognitive, and motivational processes.
• The interplay between prediction error signaling, neuromodulation, and cost-benefit analysis in specific brain circuits underlies fatigue.
• This model provides a framework for understanding how the brain regulates effort and endurance during physical exertion.