High-intensity training in normobaric hypoxia enhances exercise performance and aerobic capacity in Thoroughbred horses: A randomized crossover study.

This study investigates whether high-intensity training under hypoxic conditions (reduced oxygen) can improve aerobic capacity and performance in horses. The findings indicate that such training gives superior results compared to normal oxygen conditions, though the reduced oxygen may pose challenges for animals not adapted to hypoxic training.

Research Design and Methods

The research conducted involved eight untrained horses participating in a controlled, randomized crossover experimental design. Several parameters were considered:

• The hypoxic group: Where horses were trained under hypoxic conditions (15.0% Oxygen)
• The normoxic group: Where horses were trained under normoxic conditions (normal atmospheric oxygen at 20.9%)
• Both training procedures were carried out three days a week for a four-week period

Before and after each training session, incremental treadmill exercises were performed in a normoxic environment to test their impact. Each training session consisted of one minute of cantering at 7 m/s and two minutes of galloping at maximum oxygen consumption speed.

Key Findings

Here, various physiological parameters were observed to measure improvement in aerobic capacity and performance of the horses. The values are significantly higher under hypoxia than normoxia:

• Run time to exhaustion: +28.4% in hypoxia vs. +10.4% in normoxia
• Maximum oxygen consumption: +12.1% in hypoxia vs. +2.6% in normoxia
• Cardiac output: +11.3% in hypoxia vs. -1.7% in normoxia
• Stroke volume at exhaustion: +5.4% in hypoxia vs. -5.5% in normoxia

Implications of the Study

From the results, the study concludes that high-intensity training in hypoxia leads to a greater enhancement in the exercise performance and aerobic capacity of the horses when compared to normoxic training.

Another crucial observation was found concerning arterial oxygen saturation during exercise in hypoxia. There was a positive correlation between this parameter and changes in run time, cardiac output, and stroke volume after hypoxic training, indicating that how an individual horse responds to hypoxia could affect the benefits it receives from such training. However, there was no observed correlation between these parameters in normoxia.

Lastly, they point out that the severity of hypoxia-induced hypoxemia (limited oxygen supply in the body) during exercise could potentially be too stressful for horses that are poor responders to hypoxic training.