Please use this identifier to cite or link to this item: https://hdl.handle.net/10216/121416
Author(s): Francisco António da Silva Leite
Title: Recurrent Exercise-Induced Muscle Damage and Overtraining Syndrome: Is There Any Relationship?
Issue Date: 2019-07-15
Abstract: Strenuous and unusual physical exercise, with predominance of eccentric contractions, constitutes a vehicle that potentially induces muscular damage. It is believed that this successive muscle damage accumulation due to the training overload is the origin of a chronic condition designated by overtraining syndrome (OTS). However, there is no scientific direct evidences associating the chronic structural muscle damage induced by training overload with the occurrence of OTS. Thus, this study aim is to test the assumption that successive muscle damage accumulation due to the training overload is in the origin of the OTS, using the soleus (SOL) and tibialis anterior (TA) muscles of Wistar rats exposed to a demanding exercise training protocol. Animals were randomized distributed to a control group (CG, n=5) or to an exercised training group (EE, n=10), which performed a treadmill running training (-20º; from 25m/min, with progressive increase of 1.25m/min per day; 60 min) for 6 times/week being animals sacrificed 1 (EE1, n=5) and 3 weeks (EE3, n=5) after the beginning of the training program. Body weight, food intake, hair appearance, ability to perform work, and animals' behavior were measured during the protocol. After sacrifice, SOL and TA muscles were collected for histological analysis. Both showed muscle damage signs in EE1 and EE3 through the increase of cell degeneration, tissue necrosis, and inflammatory activity. However, the exercise training protocol was not able to induce OTS. In parallel to the occurrence of muscle injury, adaptative signs in the exercised muscles were found, such as enhanced collagen content and cross-sectional area were also observed. In conclusion, the great amount of chronic muscular damage in SOL and TA is not associated with the OTS in the short and medium-term. Further, muscle damage demonstrates different behaviors according to the type of work that each muscle performs, questioning the use of systemic markers of muscle damage as reliable methods to study the relationship between skeletal muscle damage and OTS.
Description: O exercício físico extenuante e inabitual, com predominância de contrações excêntricas, constitui um veículo indutor de dano muscular. Assume-se que a sucessiva acumulação deste dano esteja na origem de uma condição crónica designada de síndrome de sobretreino (OTS). Contudo, não existem evidencias científicas diretas que associem o dano estrutural crónico muscular com a ocorrência de OTS. Assim, o objetivo deste estudo é testar o pressuposto de que a sucessiva acumulação de dano muscular induzido pela sobrecarga do treino esta na origem da OTS, usando os músculos soleus (SOL) e tibialis anterior (TA) de ratos Wistar expostos a um protocolo exigente de treino. Os animais foram aleatoriamente distribuídos pelos grupos de controlo (CG, n=5) ou de treino (EE, n=10). O grupo EE realizou corrida em tapete rolante (-20º; a partir dos 25m/min, aumento progressivo de 1.25m/min/dia; 60 min) 6 vezes/semana, sendo os animais sacrificados 1 (EE1, n=5) e 3 semanas (EE3, n=5) após o início do programa de treino. O peso corporal, a ingestão de comida, a aparência do pelo, a capacidade de realizar trabalho e o comportamento dos animais foram mensurados durante o protocolo. O SOL e o TA foram coletados para analise histológica, após sacrifício. Ambos os músculos exibiram sinais de dano muscular nos subgrupos EE1 e EE3 pelo aumento da degeneração celular, da necrose tecidual e da atividade inflamatória. Porém, o protocolo de treino não foi capaz de induzir OTS. Paralelamente à ocorrência de lesão muscular, foram encontrados sinais adaptativos nos músculos exercitados, como melhorias no conteúdo de colagénio e na área de secção transversal. Em suma, a grande quantidade de dano muscular no SOL e no TA não está associada com a OTS a curto e médio-termo. Ademais, o dano muscular apresenta diferentes comportamentos de acordo com o tipo de trabalho desempenhado pelo músculo, questionando o uso de marcadores sistémicos de dano muscular como métodos fiáveis no estudo da relação ente o dano muscular e a OTS.
Subject: Outras ciências sociais
Other social sciences
Scientific areas: Ciências sociais::Outras ciências sociais
Social sciences::Other social sciences
TID identifier: 202266745
URI: https://hdl.handle.net/10216/121416
Document Type: Dissertação
Rights: embargoedAccess
Embargo End Date: 2020-07-14
Appears in Collections:FADEUP - Dissertação

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