Physiological Adaptations
The aim of hypoxic training is to increase oxygen utilisation by the muscles to delay the switch from aerobic respiration of muscle to anaerobic respiration where lactic acid is produced and accumulates in muscles causing fatigue.
Hypoxic training is the only practice that leads to significant improvements in all 3 stages of oxygen transport.
- Extraction of oxygen from the air in the lungs to the blood.
- Combination of the oxygen with haemoglobin on the red blood cells (RBCs) to transport the oxygen to the working muscles.
- Uptake and utilisation of oxygen by the muscle.
On return to racing in normoxic conditions, the 'extra' oxygen is then made available for energy metabolism and performance. Exposure to hypoxia stimulates up-regulation of Hypoxia Inducible Factor (HIF-1), which promotes an improvement of the body’s oxygen utilisation system at every link in the chain. Initially, pulmonary oxygen absorption is enhanced to allow more oxygen to enter the system. At the same time the kidneys signal for an increase in Erythropoietin Hormone (EPO) which stimulates the production of Red Blood Cells (RBCs) providing increased transportation for the extra oxygen throughout the body. At the next level, certain growth factors (VEGF) trigger increased capillarisation, enabling increased blood flow to tissues, muscles and brain. Finally, hypoxic training causes a boost in production and rejuvenation of mitochondria (the body’s principle oxygen sink and the location of aerobic energy production) and mitochondrial enzymes, allowing more efficient use of oxygen for energy production and enhanced enzymatic anti-oxidative defence.
Aside from these primary systemic changes, exposure to hypoxia is known to have the following beneficial physiological effects:
- Decreased average Heart Rate and Blood Pressure
- Increased production and release of Growth Hormone
- Stimulation of fat burning metabolism
- Decreased oxidative stress from Free Radicals (Reactive Oxygen Species “ROS”)
- Increased immune system response and improved cellular function and repair
Hypoxic training has revolutionised human athletic performance and it has the potential to allow greater improvements in equine and canine performance than we can otherwise produce through improved genetics alone - whilst at the same time also improving horse and dog welfare.
It is an increasingly accepted training method that will soon be in widespread use by forward–thinking trainers worldwide. Those trainers who embrace the possibilities offered by this new equipment will establish themselves at the forefront of performance sports in the future.
Passive Hypoxic Conditioning
Often known as 'Sleep High, Train Low (SHTL)', this regime only requires the horse to breathe hypoxic air whilst at rest, including when asleep. Just breathing hypoxic air lowers the oxygen level in the blood to much less than is possible even when exercising at maximum effort. Therefore, despite the fact that the horse is not undertaking any physical activity, or feeling in any way uncomfortable, the hypoxic stress stimulates a cascade of physiological events which improve the entire oxygen delivery system. Many studies have shown that 8-12 hours of exposure per day or night for a period of three weeks will create sustainable benefits.
Beyond SHTL, Active Hypoxic Training (Train High - breathing hypoxic air whilst on a treadmill or walker) can be used to build on the base benefits achieved using SHTL. The most effective regimes depend on the individual horse and the type of race it will be running. Leading stables already utilising hypoxic training to achieve performance benefits have reported help with:
- Accelerating pre-season fitness training;
- Improved recovery;
- Improved ability to maintain high levels of fitness;
- Preventing or reducing bleeding into the airways;
- Maintaining cardio-vascular fitness in injured or “at risk” horses forced to reduce training intensity;
- The final preparation for racing
With the ability to train the cardio-vascular system in hypoxic conditions rather than relying solely on the gallops it is now possible to minimise the injury risk to valuable horses in training, ensuring that they will be more likely to compete in their target races. Overall, horse welfare is improved.
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