Central and Peripheral Fatigue in Physical Exercise Explained: A Narrative Review

Abstract

The study of the origin and implications of fatigue in exercise has been widely investigated, but not completely understood given the complex multifactorial mechanisms involved. Then, it is essential to understand the fatigue mechanism to help trainers and physicians to prescribe an adequate training load. The present narrative review aims to analyze the multifactorial factors of fatigue in physical exercise. To reach this aim, a consensus and critical review were performed using both primary sources, such as scientific articles, and secondary ones, such as bibliographic indexes, web pages, and databases. The main search engines were PubMed, SciELO, and Google Scholar. Central and peripheral fatigue are two unison constructs part of the Integrative Governor theory, in which both psychological and physiological drives and requirements are underpinned by homeostatic principles. The relative activity of each one is regulated by dynamic negative feedback activity, as the fundamental general operational controller. Fatigue is conditioned by factors such as gender, affecting men and women differently. Sleep deprivation or psychological disturbances caused, for example, by stress, can affect neural activation patterns, realigning them and slowing down simple mental operations in the context of fatigue. Then, fatigue can have different origins not only related with physiological factors. Therefore, all these prisms must be considered for future approaches from sport and clinical perspectives.

Temporal effects of two interferential current applications on peripheral circulation in children with hemiplegic cerebral palsy

“…The cholinergic sympathetic nerve fibers cause vasodilatation during muscular exercises, which increase blood supply to the muscle and accelerates chemical reactions, leading to proper contraction, delayed fatigue, and early recovery from fatigue. 26 , 27 …”

Efficacy and safety of fermented Prunus mume vinegar on fatigue improvement in adults with unexplained fatigue: A randomized controlled trial

“…The sample size was calculated using nQuery Advisor software v. 7.0 (Statsols, Cork, Ireland). The difference in pre-and post-treatment changes in the total score of the FSS between the PV and placebo groups was set at 0.64 based on a previous similar study ( 30 ). The estimated sample size was 32 participants per group for 80% power to detect a difference of 0.64, assuming a standard deviation of 0.9 in the primary outcome variable and an alpha error of 5%.…”

Influence of iron supplementation on fatigue, mood states and sweating profiles of healthy non-anemic athletes during a training exercise: A double-blind, randomized, placebo-controlled, parallel-group study

“…In particular, women have an increased risk of low iron status as a result of exercise-related iron loss combined with iron loss due to menstruation [ 1 , 3 , 11 , 23 , 24 ]. Also, iron insufficiency can have a negative impact on physical performance, and athletes may suffer from non-specific symptoms such as fatigue, weakness, and lethargy [ 13 , 25 , 26 ]. The mechanisms that cause iron loss during exercise are hemolysis due to mechanical forces and oxidative stress, gastrointestinal and urinary tract bleeding due to microscopic lesions, and extreme sweating, which can result in iron deficiency [ 13 ].…”