If you visit a high-altitude location and try to perform your normal endurance exercise regimen, you’ll find it more challenging because the air you are breathing is different than sea-level air. Specifically, there is less oxygen contained in a given volume;
hence, your cardiovascular system must work harder to provide the oxygen necessary to support the exercise’s aerobic energy
requirement. Interestingly, this increased challenge provides a stimulus that forces your aerobic system to adapt to a higher level
of development; however, this training effect can be offset by the reduction in exercise work rate that the altered environment mandates.
“Live high, train low” is a training paradigm that has been investigated as a best-of-both-worlds solution. In theory, living at high altitude to enhance the body’s adaptive response while exercising at a lower one to maintain training work rate seems to be the perfect way to maximize training adaptations. However, applying this methodology in practice is logistically challenging.
Masks that are purported to simulate altitudes ranging from 914 to 5486 m are currently being marketed to circumvent this limitation; however, it is important to look to the research to determine whether “revolutionary” exercise products like these are legitimate before making an investment. A recent study in Journal of Sports Science and Medicine provides such insight regarding altitude-simulation masks.To determine the effect of altitude-simulated training, Porcari et al. assigned 25 moderately-trained subjects into one of two groups. Subjects in one group trained while wearing the Elevation Training Mask 2.0 while subjects in the other group performed the same exercise while breathing normally. Consequently, the latter group served as a control to rule out the influence of exercise training per se.
On the initial visit to the lab, participants performed a maximal cycling test to determine the highest power output they could produce, the highest rate at which they could consume oxygen (VO2max) and the highest rate at which their heart could beat. From gas-exchange data collected during this test, two “thresholds” that can be identified during incremental exercise (ventilatory threshold and respiratory compensation threshold) were also determined. Finally, subjects performed tests that provide information regarding pulmonary function and blood was drawn for analysis during this first testing session.
Following preliminary testing and familiarization to the exercise protocol, participants completed a six-week program comprising two weekly sessions of high-intensity interval cycling. Each session involved 10 repeat 30-second bouts at the peak power achieved on the initial test separated by 90 seconds of cycling at a low work rate for recovery.Training work rate was progressed over the course of the study to keep subjects challenged at the same perceived level of exertion and altitude simulation was increased every two weeks from 914 to 3658 m for the mask group. The same battery of tests was performed following the training intervention so that training-induced adaptations could be compared.
When results were tabulated, responses for the most part were similar regardless of whether the mask was worn. For example, no improvement in pulmonary function (forced vital capacity, forced expiratory volume in one second, the ratio of the latter to the former and maximal inspiratory pressure) or blood composition (hemoglobin and hematocrit) were observed in either group. Conversely, VO2max and peak power output were each increased, but the improvements were similar between groups. Indeed, the only measurements that improved in the mask group exclusively were ones that were related to the two thresholds that signal changes in the ventilatory response when exercise intensity is progressed from minimal to maximal effort.
In summary, the adaptive responses to exercise that have been demonstrated to be enhanced due to reduced oxygenation at a high-altitude environment were not facilitated by the addition of an altitude-simulation mask during high-intensity interval training. Specifically, VO2max, which is the criterion index of aerobic fitness, was increased to a similar extent regardless of whether the mask was worn. Consequently, it appears that the mask does not simulate a high-altitude environment. This conclusion was also supported by the fact that the oxygen saturation of the blood during exercise for the mask-wearing subjects was not lower than what would be expected under normal circumstances during this type of exercise. However, improvement in the ventilatory thresholds that only occurred for subjects in the mask group suggest that the mask did alter the stimulus that was applied during training. The authors suggest that this effect was simply a function of the increased resistance to breathing that was present when exercising with the mask. In this regard, a growing body of research suggests that regularly-performed “inspiratory muscle training” (IMT) reduces ventilatory-muscle fatigue and improves endurance performance independent of changes in cardiorespiratory function.
Importantly, most of these previous studies involve IMT done separately as a stand-alone workout utilizing a small resisted-breathing device. However, recent research indicates that this type of training can also be applied while performing conventional endurance exercise via use of a mask-like device with valves that provide inspiratory and expiratory resistance. But either way, the stimulus is related to resistance and, therefore, not associated with an alteration of the oxygen content of the air that is passing through the device.
Fred DiMenna is a two-time Natural Mr. United States and retired WNBF drugfree bodybuilder who has a PhD in exercise physiology from University of Exeter in the U.K. He is main or contributing author of over 30 articles listed on PubMed and serves as an adjunct professor at both Columbia Teachers College and Adelphi University. Visit him at www.freddimenna.com or e-mail at firstname.lastname@example.org.