Abstract
We investigated the effects of low intensity exercise during the breaking period on cardiorespiratory function in twelve Thoroughbred yearlings. The horses were broken to handling and riding according to typical breaking program, and breaking was defined as a period of about 8 weeks covering bitting, saddling, longeing exercise and track exercise at trot and slow canter. Each horse performed an incremental exercise test on a treadmill before (pre-test) and after (post-test) the breaking period. Vo2max was increased significantly after the breaking period (pre-test: 134.8 ± 8.9 ml/kg/min, post-test: 151.3 ± 7.9 ml/kg/min). There were no significant difference between the peak HR and La values before and after breaking. Breaking also caused no change in the relationship between speed and HR or La. The peak PCV value was significantly higher after breaking period. These results suggest that Thoroughbreds already have considerably high cardiorespiratory function at the early stage of their lives before breaking, and also suggest that cardiorespiratory function is enhanced through the breaking period, which is necessarily experienced by young racehorses.
