Physiological and biochemical parameters were evaluated in Quarter Horse during three-barrel training, in three times: T0 (before warm-up), T1 (after warm-up), T2 (after completing the exercise, performing only one course), T3 (after resting for 20 minutes of the course), and T4 (after resting for 40 minutes of the course). The parameters evaluated were: heart rate (HR), respiratory rate (RR), rectal temperature (RT) and capillary filling time (ECT); Serum concentrations of sodium, potassium, chloride, total calcium, BUN, creatinine, osmolarity, creatine kinase, aspartate transaminase; Plasma concentrations of total protein (PT), glucose, and lactate. HR, RR and RT increased shortly after the course (T2) but were restored after 40 minutes of rest. Lactate concentration increased after conditioning, but at low concentrations, but high levels occurred after the course (T2), and although decreased after 20 (T3) and 40 minutes (T4) of the course, it was still above normal limits. There were no significant changes in the other parameters. At the end of a single course of three-barrel, the exercise of maximum intensity did not cause significant biochemical variations in horses, except for lactate, which increased to levels of hyperlactatemia, and was not restored until 40 minutes of rest, even with the physical parameters already recovered.
equine; exercise; training; biochemist; barrel