OXIDATIVE STRESS IN STANDARDBRED HORSES DURING OFFICIAL RACES OF 1600 AND 2000 METERS

In thoroughbred race horses, as in other species subjected to physical activity, there is a rise in the imbalance between free radical production and antioxidant agents which leads to oxidative stress. This stress may produce damage in several bio-molecules creating metabolic alterations affecting physical performance. The aim of this study was to find possible relationships between physical exercise and oxidative stress in trained horses. In order to achieve this we reported the results obtained while studying the effect of a physical exercise test on two groups of standardbreds. In particular, the study assessed levels of creatine kinase (CK) and aspartate amino transferase (AST) to evaluate possible muscle-cell membrane damage; reactive oxygen species (ROS), thiol antioxidant barrier (SHp) and antioxidant barrier (Oxy-adsorbent) to evaluate oxidative stress. Two groups of healthy standard bred (Ga and Gb) trained for 1600 and 2000 meter races were used for the study. Blood samples from all horses were collected at rest, immediately after racing, and 30 and 6 hours after racing. The ANOVA for repeated measures showed the highly significant effects of training on some of the studied parameters in both groups (Ga and Gb). Our results seem to indicate that in trained standard breeds acute exercise generates free radicals but they are unable to cause possible muscle-cell membrane damage. However, in order to know whether the inhibition of oxidative processes during exercise benefits physical performance, it would be necessary to simultaneously measure parameters relating to work capacity such as blood lactate, heart rate and oxygen consumption, both in basal conditions and at different times after a standardized race.