Altitude training

At UCRISE we use a system constructed by Altitude Training Systems, a Sydney company that specialises in altitude training facilities. To simulate a high altitude environment, a series of compressors and blowers pumps nitrogen into the environmental chamber (nitrogen dilution).  As the nitrogen in the chamber builds up, the composition of the air in the room changes and the oxygen availability decreases from normal ambient levels (~20.93%) to a level that simulates the availability of oxygen in high altitude environments (14-16%). 

Simulated altitude is different to natural altitude in that at natural altitude, the composition of the air doesn't change (oxygen stays at 20.93%, carbon dioxide ~0.04%, nitrogen~78%). Instead, as altitude increases, the partial pressure of all gases, including oxygen, decreases. By changing the composition of gas within the environmental chamber, altitude simulation reduces the oxygen availability to the same degree as natural altitude, thus creating a hypoxic (low oxygen) environment.

Altitude or hypoxic (low oxygen) training is used by athletes, sport scientists and coaches for four reasons: 

• to evoke additional physiological adaptation, 
• to increase or maintain physiological/metabolic training load while maintaining or decreasing mechanical load, 
• to pre-acclimate to hypoxic conditions before competing at high altitude, 
• to maintain fitness when injured or unable to complete normal/prescribed training.

During hypoxic training sessions at UCRISE you will train at a simulated altitude of 1800-3000 m. This is the optimal range to evoke beneficial adaptation and increase training load without unduly compromising the exercise intensity that can be sustained during training sessions. Additionally, exposure to altitude greater than 3000 m above sea-level greatly increases the risk of hypoxic illness and as such, any training sessions at UCRISE with a hypoxic dose in excess of 3000 m above sea-level require clearance from the University of Canberra Human Research Ethics Committee.

Due to the reduction in oxygen availability and the manner in which the hypoxic environment in the chamber is generated you may notice some slight changes to the way you feel while exercising. These changes include feeling slightly more breathless and having a slightly elevated heart rate compared to when exercising at the same intensity at sea-level. Additionally, as the nitrogen rich air being pumped through the chamber to simulate high altitude is dry and you will be breathing more, you may notice that your mouth is slightly drier, and you are thirstier than usual. However, these changes are normal responses to the hypoxic environment and apart from taking a more considered approach to fluid intake to mitigate the drier air (e.g. drinking a little bit more during training sessions), they don't require any specific attention.

The changes most people associate with altitude and altitude training, relate to haematological adaptations that improve the oxygen carrying capacity of the blood. However, such adaptations require a larger hypoxic dose (14+ hours per day for at least two weeks) than that provided by intermittent hypoxic training sessions (1-2 hours per day, 1-7 sessions per week). Instead, the additional training stimulus provided by hypoxic training is likely to evoke peripheral adaptation within the muscle and surrounding vasculature. These adaptations are directly influenced by the type of training done in a hypoxic environment and include:

• Increased mitochondrial density
• Increased capillary density
• Increased oxidative enzyme activity
• Improved blood perfusion of working muscle (more blood flow)
• Increased glycolytic enzyme activity
• Up-regulation of factors involved in mitochondrial biogenesis

Such adaptations have been associated with:

• Increased VO2 max
• Increased anaerobic power output
• Improved repeat sprint ability and fatigue resistance
• Improved time-trial performance
• Improved running economy
• Increased VO2 max and exercise performance at high altitude

To optimise the adaptive and performance response, clients should aim to complete two sessions of hypoxic training per week over 4-6 weeks. However, one hypoxic session per week can be sufficient if the primary aim of hypoxic training is to increase/maintain training load while maintaining/decreasing mechanical load.

The time course of any adaptations or performance changes occurring as a result of hypoxic training will be variable between individuals. Research indicates the adaptation and performance change arising as a result of altitude training can occur after as few as 10 hypoxic training sessions over 10 days. However, a more moderate dose (2-4 sessions per week) over a sustained period of time (4+ weeks) is recommended to increase the likelihood of physiological adaptation and performance improvements. Clients can expect any changes to last for the equivalent time of their hypoxic training exposure, however the time course of change will vary between individuals and be highly dependent on training completed once the hypoxic training block ceases. However, if the aim of simulated altitude training is to acclimate for competition or exercise at high altitude, sessions should not finish until immediately before departure to the high altitude location as the acclimation benefits are likely to dissipate rapidly once simulated altitude exposure ends.

Any adjustment to training sessions should be minimal and will depend on the intended purpose of the hypoxic training and the overall volume and intensity of other training sessions.

If the overall aim of hypoxic training is to induce further training load without increasing mechanical load or training duration, then no adjustments should be made to other training sessions and hypoxic training should simply replace an equivalent session at sea-level. Alternatively, hypoxic training sessions could be added to an existing training program to further increase training load.

If the overall aim of hypoxic training is to evoke further adaptation arising as a result of the hypoxic dose, then hypoxic training sessions should be the focal point of each weekly training cycle. Therefore, to ensure training during hypoxic sessions is of good quality, schedule rest or easy training on the day before your session so you are recovered and fresh. During these hypoxic training sessions, consider using a training protocol consisting of high intensity interval training (above lactate threshold) or repeated sprints.

Training in a low oxygen environment is very safe and the risk of an adverse reaction is minimal. To ensure client safety, hypoxic training sessions are monitored by UCRISE staff members who are completing post graduate studies in sport and exercise science. Additionally, all clients wear a pulse oximeter to ensure oxygen saturation remains at a safe level throughout hypoxic sessions.