The study was carried out to investigate the effect of prolong
submaximal exercise on heart rate reflecting the performance of endurance horses after covering distances of 40 and 80 km races. This study was conducted in Malaysia to determine the post-race
heart rates of endurance horses based on distances for the eliminated horses and those that completed the races with good
performance. Heart rates of competing endurance horses were examined at pre and post-race. Thirty-four endurance horses were sampled; N = 9 (40 km) and N = 9 (80 km) were the good performance horses while, N = 3 (40 km) and N = 13 (80 km) were the poor performance horses
eliminated from the race. The mean heart rate of the good performance horses in the 40 km category was 53 ± 8 bpm and that of
the 80 km in the good performance category was 56 ± 7 bpm, while the eliminated horses of the 40 km group had 74 ± 17 bpm and those in the 80 km group had 78 ± 7 bpm. The study showed that eliminated
horses in the 40 and 80 km categories both exhibited high heart rates compared to the good performance horses that were in the same racing category. Thus, the heart rates of horses during training may be used to predict performance based on distances covered in endurance races.

Exercise-induced changes of pro-oxidant generating substances and muscle fibre damaging enzymes are the possible causes of reduced performance in endurance horses. Therefore, this study aims to investigate on the performance of different age and gender using biochemical profile of endurance horses during 120 km endurance race. One hundred and eighty four Arabian endurance horses were physically examined and blood samples were collected post-race.&#xD;After physical examination, the MD (F, n= 44; G, n = 86) and SC (F, n = 20; G, n = 34) were identified. T-test and pairwise correlation were used for the analysis. There were significant differences in&#xD;CK, uric acid, lactate and age (P<0.0001) respectively between the gender in the MD and SC. There were significant differences in AST (P<0.0029) and GGT (P<0.0039) respectively between the gender in the&#xD;MD and SC. In conclusion age and gender significantly affect performance of endurance horses in relation to biochemical profile during 120 km endurance race. Therefore, further studies are required to determine if age, gender and biochemical profile could be used to assess performance in endurance horses.