Increase stamina and improve endurance (aerobic performance)
Using the ETM has shown to cause arterial hypoxemia, but in a different way compared to real altitude training. Using the mask causes inadequate ventilation, resulting in an imbalance between oxygen uptake and CO2 removal, and can, therefore, lead to hyperventilation. This, in turn, causes the ETM to increase the perceived exertion while training .
Furthermore, when attempting to use the ETM in order to increase an individual’s VO2max, studies have shown inconclusive results. For example, some studies have found no significant difference in VO2max by wearing the mask [4, 12]. On the other hand, another study found an increase in VO2max in subjects wearing the mask, but importantly, it also found improvements in those who did not wear the ETM .
It has also been stated that the ETM does not elicit a response for improving cardiorespiratory fitness . In line with this, as the ETM does not simulate an altitude environment, the desired effects of high-altitude training (e.g. increase in red blood cells) will not exist . As a result, wearing the ETM in training settings with the purpose of increasing stamina and improving endurance is not supported with conclusive evidence.
Increases strength and power (anaerobic performance)
Finally, ETM is claimed to help athletes achieve better performance during high-intensity interval training and strength training, under the assumption that oxygen restriction may result in adaptations relating to an enhanced buffering capacity .
This is also currently inconclusive and more research is needed to know if the ETM would compromise the ability to train at intensities high enough to elicit such adaptations . Moreover, its use does appear to negatively influence peak velocity during both the back squat and the bench press exercises, which may attenuate training outcomes over time .
Whether strength training under hypoxic conditions can improve performance has recently been studied with promising results in terms of hypertrophy and muscular power [2, 3, 13]. Additionally, resistance training during hypoxic exposure has been shown to contribute to advanced fibre-type recruitment that may contribute to greater increases in maximal strength .
However, in terms of the ETM and strength training, limited research is available regarding adaptations in strength and power performance when using the ETM. A study published in 2017 suggested that wearing the ETM while performing a strength training session appears to not only hinder the ability to maintain working velocity during the bouts, but also affect the athlete’s ratings of alertness and focus for the task .