Introduction

Before we begin, it is important to clarify some of the common terminologies which will be present throughout this article:

• Hypoxia – is a state where the tissue demand of oxygen exceeds the supply of oxygen.
• Hypoxic – is described as breathing a gas mixture which contains less than 21% oxygen.
• Normobaric – is a state of normal barometric pressure equivalent to that at sea level.
• Hypobaric hypoxia – is a condition where low pressure and reduced oxygen availability is present (e.g. high-altitude).
• Normobaric hypoxia – is a condition where normal pressure but reduced oxygen availability is present at terrestrial altitude (e.g. simulated altitude).
• Elevation/altitude training – is a training method used in an environment with a reduced partial pressure of oxygen. The aim is for the body to produce a greater amount of erythropoietin (EPO), which increases the red blood cells produced in the body.

Exercising aerobically [1] and anaerobically [2, 3] at altitude has been proven to increase VO2max, as well as enhancing many other physiological adaptations (e.g. increased muscular power and hypertrophy). Several approaches and modalities have therefore been utilised to simulate altitude training, including normobaric hypoxia via nitrogen dilution (hypoxic department); supplemental oxygen; hypoxic sleeping devices; and intermittent hypoxic exposure [4]. Furthermore, simulated altitude training has become increasingly popular for its convenience as opposed to a cold environment, harsh terrain, and low-oxygen pressure that often accompanies high-altitude training [4].

In previous years, the various equipment used to induce hypoxia has been expensive, however, with the purpose of making this modality of training available to the broad public, new and more affordable devices have been introduced to simulate the same effects as elevation training in a more familiar environment [1]. Doing so makes it more convenient for athletes to get similar effects without having to travel to high-altitude environments [4].

One of these devices, the infamous Elevation Training Mask (ETM), is said to simulate altitude and to induce a normobaric hypoxic condition, or minimise the amount of air allowed to be consumed by an individual [1]. An ETM is a patented pulmonary resistance training device that is currently a pioneer on the market. This device covers the user’s mouth and restricts air intake into dual channels and has an additional vent for the discharge of exhaled air. Additionally, the mask includes a variety of adjustable resistance caps, as well as three adjustable flux valves. Furthermore, the individual can progressively increase the resistance to simulate from 900 to 5,400 meters above sea level [4].