miRNAS and target genes are regulated post-training in quarter horse athletes

• The physiological stress is associated with reduced athletic performance. • The hematological parameters of athletic horses showed variations proportional to the level of exercise effort. • The physiological, hematological, and molecular parameters become indicators of equine health. • The ALDOA and EGFR genes and miR-133b are associated with post-training recovery. • The miR-1260b was modulated after aerobic exercise, being reported for the first time. In the context of Brazilian equestrian sports, the Quarter Horse (QH) breed has the third largest population of registered horses and stands out for its numerous abilities in various disciplines. Studies on equine health and athletic performance parameters are scarce, especially involving molecular markers. This study aimed to investigate the differential expression of microRNAs and target genes involved in metabolic pathways of exercise and to assess hematological and clinical changes in 10 horses ( Equus caballus Linnaeus) of the QH breed under different physiological conditions. Horses of both sexes, aged 6 years, weighing between 400 and 513 kg (442,3kg Mean), with the same housing, feeding, and training management throughout the experiment. The horses were subjected to a race with obstacle deviation. The results of clinical, hematological, and molecular parameters showed significance (p