Adaptações fisiológicas e metabólicas ao exercício físico agudo e crônico erelações com o padrão de expressão de miRNAs circulantes em homens saudáveis

Abstract

The mechanisms of adaptation and acute responses caused by physical exercise are not fully understood. Serum concentrations of specific biomarkers signal adaptive responses. The expression of circulating miRNAs (c-miRNAs), intracellular mediating molecules essential for numerous biological processes, can be used to understand the changes induced by exercise. The present study aimed to determine the variations of biochemical and physiological biomarkers related to tissue damage and the inflammatory process, and the expression of c-miRNAs of healthy men (18.5 ± 0.5 years), conditioned and not physically conditioned, after performing acute resistance exercise (RE) and chronic training. Participants were classified as unconditioned (n = 10) or physically conditioned (n = 10), according to the Cooper test. Blood samples were collected at three times: baseline, 1h, 24h-post RE (maximum repetitions of arm flexion, alternating and without intervals, with maximum repetitions of squats) and after 12 weeks of chronic training (continuous running) , in addition, scapular strength, lower limbs and lumbar spine tests were performed. After acute RE, both groups showed the same behavior as biochemical markers (increased serum creatine kinase concentration after 1h and 24h (P <0.05) and maintenance of serum interleukin-6 concentration), however the expression of c-miRNAs were dynamic and distinct between groups, in the unconditioned group a reduction in the expression pattern of c-miRNAs mediating muscle function was observed (c-miR-1-3p post- 1h; c-miR-133a post-24h ) and in the conditioned group reduced expression of the mediator of the inflammatory process (c-miR-21-3p). After chronic exercise, systemic adaptations were observed, such as increased VO2max in the unconditioned group and strength in both groups. There was a reduction in the expression of c-miR-21-3p and -133a in the non-conditioned group, which can be considered as a modification due to the increase in physical conditioning, generated by chronic training. Our results, taken together, point to the importance of physical conditioning in the study of c-miRNAs. The increase in physical conditioning, possibly, influenced the expression profile of specific c-miRNAs of tissue damage and inflammatory process. C-miRNAs can be promising biomarkers capable of indicating the response or adaptation process caused by physical exercise.