Sarcomere disruptions of slow fibres resulting from mountain ultramarathon
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Objective: To investigate changes after a mountain ultramarathon (MUM) in the serum concentration of fast (FM) and slow (SM) myosin isoforms, which are fiber-type-specific sarcomere proteins. The changes were compared against creatine kinase (CK), a widely used fiber-sarcolemma-damage biomarker, and cardiac troponin I (cTnI), a widely used cardiac biomarker. Methods: Observational comparison of response in a single group of 8 endurance-trained amateur athletes. Time-related changes in serum levels of CK, cTnI, SM, and FM from competitors were analyzed before, 1 h after the MUM, and 24 and 48 h after the start of the MUM by 1-way ANOVA for repeated measures or Friedman and Wilcoxon tests. Pearson correlation coefficient was employed to examine associations between variables. Results: While SM was significantly (P = .009) increased in serum 24 h after the beginning of the MUM, FM and cTnI did not change significantly. Serum CK activity peak was observed 1 h after the MUM (P = .002). Moreover, serum peaks of CK and SM were highly correlated (r = .884, P = .004). Conclusions: Since there is evidence of muscle damage after prolonged mountain running, the increase in SM serum concentration after a MUM could be indirect evidence of slow- (type I) fiber-specific sarcomere disruptions.
CitationCarmona, G., Roca, E., Guerrero, M., Cussó, R., Irurtia-Amigo, A., Nescolarde Selva, Lexa, Brotons, D., Bedini, J., Cadefau, J. Sarcomere disruptions of slow fibres resulting from mountain ultramarathon. "International Journal of Sports Physiology and Performance", 02 Novembre 2015, vol. 10, núm. 8, p. 1041-1047.