Fatigue is a Brain-Derived Emotion that Regulates the Exercise Behavior to Ensure the Protection of Whole Body Homeostasis

Abstract

An influential book written by A. Mosso in the late nineteenth century proposed that fatigue that “at first sight might appear an imperfection of our body, is on the contrary one of its most marvelous perfections. The fatigue increasing more rapidly than the amount of work done saves us from the injury which lesser sensibility would involve for the organism” so that “muscular fatigue also is at bottom an exhaustion of the nervous system.” It has taken more than a century to confirm Mosso’s idea that both the brain and the muscles alter their function during exercise and that fatigue is predominantly an emotion, part of a complex regulation, the goal of which is to protect the body from harm. Mosso’s ideas were supplanted in the English literature by those of A. V. Hill who believed that fatigue was the result of biochemical changes in the exercising limb muscles – “peripheral fatigue” – to which the central nervous system makes no contribution. The past decade has witnessed the growing realization that this brainless model cannot explain exercise performance. This article traces the evolution of our modern understanding of how the CNS regulates exercise specifically to insure that each exercise bout terminates whilst homeostasis is retained in all bodily systems. The brain uses the symptoms of fatigue as key regulators to insure that the exercise is completed before harm develops. These sensations of fatigue are unique to each individual and are illusionary since their generation is largely independent of the real biological state of the athlete at the time they develop. The model predicts that attempts to understand fatigue and to explain superior human athletic performance purely on the basis of the body’s known physiological and metabolic responses to exercise must fail since subconscious and conscious mental decisions made by winners and losers, in both training and competition, are the ultimate determinants of both fatigue and athletic performance.

Fatigue experiences in competitive soccer: development during matches and the impact of general performance capacity

“…To this end, a large-scale cross-sectional survey was distributed among (sub)elite soccer players. In line with recent literature, which proposes a central role for perceived effort and exertion in explaining the fatigue-performance relation [15,16], our study focused on the subjective experience of fatigue. It was hypothesized that fatigue increased during both halves and decreased during half time.…”

“…Fatigue experiences play an important role in performance decrements under highly demanding circumstances [15,16] and could indicate higher injury risks [27,28]. The current study aimed to provide insight in general experiences of match fatigue, to identify potential differences in fatigue between players' positions, and -based on effort-recovery theory [9] -to identify the contribution of general performance capacity to these fatigue experiences.…”

Physiological and Psychological Effects of Deception on Pacing Strategy and Performance: A Review

“…The RPE template has been shown to be set, not in accordance with the exercise intensity, but in relation to the exercise duration and to increase as a linear function of the percentage duration remaining [26,27] in such a way that the initial rate of increase can accurately predict the endpoint [28] .…”

Kinetic and Kinematic Changes during a 30-Repetition Bout of the Barbell Clean

“…During the initial circuits where the repetitions were high participants may have adopted less knee flexion at the bottom of the movement to ensure that the set could be completed. In contrast, towards the end of the program when the number of repetitions to be performed were lower, the participants would have to adopt less of an anticipatory behavior [21] and could produce the knee angle they would normally use when squatting.…”