The effects of training on ventilation and blood gases in exercising thoroughbreds.

The research investigates the impact of a 16-week training program on ventilation and blood gases during exercise in Thoroughbred horses. It finds that while the training doesn’t significantly affect ventilation and respiratory patterns, it does lower peak inspiratory flow rates during cantering and leads to decreased arterial oxygen tension, potentially suggesting minimal pulmonary adaptation despite improvements in cardiovascular and muscular functions.

Training Protocol and Initial Testing

• The study involved six Thoroughbred horses that were sufficiently detrailed. The horses underwent a 16-week training program, which embodied a common method used for racehorses in the U.K.
• Prior to and after the training program, the horses were subjected to standardized treadmill exercise tests. These tests included a two-minute canter at two different speeds (8 m/s and 10 m/s) and a two-minute gallop at a high speed (12 m/s).

Methodology and Sample Collection

• To measure respiratory flow rates, the researchers used ultrasound flow transducers. These devices were used to accurately measure the airflow during the horses’ respiration process.
• Blood samples were collected from the horses both from a transverse facial artery and the right atrium to detect and examine blood gases and other parameters.

Effect on Ventilation and Respiratory Pattern

• The research found that the 16-week training program did not significantly alter minute ventilation, respiratory frequency, or tidal volume in the horses. This suggests that the training regimen did not substantially change the basic respiratory characteristics of the horses.

Impact on Inspiratory Flow and Oxygen Tension

• Following the training, the horses exhibited a lower peak inspiratory flow rate during cantering at 8 m/s and 10 m/s. However, there was no change observed during gallop at 12 m/s.
• Arterial oxygen tension decreased during the trot and canter post-training. This signifies that the amount of oxygen reaching the arteries reduced following the training.

Alterations in Blood Lactate Concentration

• The blood lactate concentration following a high-speed gallop (G12) reduced from an average of 10.5 mmol/l before training to 7.7 mmol/l after training. This decrease in lactate concentration evidences improved metabolic response to the exertion caused by the gallop exercise.

Interpretation and Implications

• A significant takeaway from this research is that the training program raised the level of exercise-induced arterial hypoxaemia, suggesting a lack of pulmonary adaptation to training.
• This implies that despite the improved cardiovascular and muscular functions resulting from the training program, the pulmonary system may not have adapted as efficiently. This observation raises questions about the nature of training programs for horses, calling for more investigations to balance physical conditioning and pulmonary health.