Fadiga acumulada pelo exercício e uso do extrato de chá verde (Camellia sinensis) na prevenção de seus efeitos

Abstract

Muscle fatigue is a physiological and transient phenomenon that generates loss of strength and endurance, with consequences for muscle damage, oxidative stress and inflammation. For the recovery of the muscle involved in fatigue, it is necessary to allow the homeostasis repair process to occur, which can take up to 96 h. There are situations, such as in the accelerated rehabilitation of injuries or in sports competitions, in which a process of fatigue is imposed on the muscle for consecutive days of exercises, without allowing adequate time for recovery, which can lead to a condition of cumulative fatigue. It is in the interest of therapists, coaches and athletes to better understand how to quantify this condition in order to avoid or reduce the effects of cumulative fatigue. However, both the quantification of cumulative fatigue (such as through markers of performance and stress during exercise) and strategies for its prevention and treatment (such as nutritional interventions with green tea extract, found in Camellia sinensis), are challenging. With a combination of experiments carried out during the period of the coronavirus pandemic (2020-2023), the objective of this thesis was to investigate indicators of cumulative fatigue and its effects on performance in high-level sports competitions, to determine the reliability of techniques to monitor muscle fatigue, and to evaluate the potential of green tea extract as a low-cost intervention to minimize the effects of cumulative fatigue. We interpret our main results as indicating that (1) competitions involving many consecutive days of exercise lead to cumulative fatigue; (2) cumulative fatigue can be identified from volume and intensity information monitored during exercise; (3) performance losses due to fatigue accumulation are influenced by the choice of rest days throughout the competition; (4) skin temperature measurements using infrared thermography can help identify markers of cumulative fatigue in laboratory tests; (5) administration of green tea extract prior to exposure to the condition of cumulative fatigue is associated with a reduction in markers of muscle damage and oxidative stress; (6) administration of green tea extract prior to exposure to the cumulative fatigue condition minimizes reductions in neuromechanical variables associated with force production in the cumulative fatigue condition. We consider that the information included in this thesis contributes to the advancement of knowledge on the subject, with an integrative approach to concepts and tools from different areas, helping to better understand the processes involved in the mechanism of cumulative fatigue, its better quantification and monitoring, and ways of prevention.