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UBC Theses and Dissertations

Short-term resistance exercise training attenuates muscle damage and alters transcription of muscle extracellular matrix regulators in response to 300 eccentric contractions in young adults Li , Ching Wah Donna


A maximal eccentric (ECC) bout can confer protection by reducing exercise-induced muscle damage (EIMD) following a subsequent ECC bout, this is known as the repeated bout effect (RBE), a phenomenon that results in large non-specific translational and transcriptional responses. Resistance exercise training (RET) stimulates similar adaptations which becomes more refined with continuing training. It was hypothesized that RET and RBE may share a common mechanism involving remodeling of the extracellular matrix (ECM). Healthy young adults (6 female, 10 males; 20.9 4.1 years) performed 6 sessions of unilateral RET with the contralateral leg acting as a control prior to 2 bilateral bouts (B1, B2) of 300 eccentric knee extensions separated by 21 d. Bilateral muscle biopsies were obtained before and 48-hours after each bout. Muscle damage assessed as the area under the curve for isometric force loss over 72-hours following ECC, was attenuated in B1 by RET (42%±4.76, p=0.035). Protection conferred by B1, resulted in complete recovery of force loss by 48h. ECC elevated expression of Transforming Growth Factor-Beta (TGF𝛽, p=0.018) and Collagen Type IV (COL4A1, p=0.027) only in the RET leg after each bout, while Matrix Metalloproteinase-2 (MMP2) mRNA increased after ECC only in the control leg (p=0.049). These results collectively suggest that short-term RET modifies the transcriptional response of ECM regulators to bouts of high volume ECC exercise which may partially underpin the observed attenuation of ECC induced EIMD by prior RET. Further analysis is required to determine if altered transcription of ECM regulators is also reflected at the protein level.

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