Elevation Masks are STILL a Useless Torture Tool & Fashion Accessory for Gymrats, But Some Athletes May Benefit

The masks are no alternative for altitude training - that's quite certain.

It is more than one year ago that I've highlighted the results of Warren's study in the International Journal of Exercise Science in the SuppVersity Facebook News. In view of the fact that I still see people being confused by the producers of respective fashion gadgets (yes, that's what it is: it's cool to look like Bane, when you're training, but it's not effective), I do yet think that it's worth writing a short article about the myth that a mask that does nothing, but obstruct your breath would yield a training effect that was even remotely comparable to the effects of real hypoxia training, where you can breathe freely but don't get enough oxygen from the air you breathe from a tank or at high altitudes.
In the aforementioned study, the researchers from Texas A&M tried to figure out whether so-called "elevation training masks" (ETMs) would boost the VO2max of male Reserve Officers Training Corps (ROTC) cadets. For this purpose, Warren et al. recruited fourteen male ROTC cadets (age 20.00 ± 1.8 yrs, height 174.35 cm ± 3.1 cm, weight 76.75 kg ± 11.09 kg, body fat 13.88% ± 4.62%) who were then randomly assigned to either the control or experimental group, respectively. All participants did the standard ROTC program, the authors describe as follows:

"In conjunction with each training session, there was a warm-up and cool-down period. The first training session consisted of one moderate-distance run that was approximately 2 miles and was performed in an interval style with 60 seconds of slow jogging followed by a 10 second sprint. The second day had participants rotate through an 8-station body weight circuit. The longest run was always on the third training day, which required the cadets to run approximately 4 miles at a steady pace" (Warren. 2017).

The training period of the study was seven weeks. Each subject participating 3 days per week. Over the course of the seven-week training sequence, the breathing resistance on the "elevation mask" was increased from a resistance that was meant to simulate 3,000 feet above sea level in 3,000 feet intervals. Accordingly, the resistance at the beginning of week 4, after which no further increases were undertaken, was set to what the producers of the masks claim would simulate training at 12,000 feet (for Europeans: that's 3657.6 meters) above sea level.

Figure 1: Changes in VO2Max (left) for each subject and abs. VO2Max pre- vs. post data for all subjects (Warren 2017).

As Warren et al. point out, "[t]his specific progression was chosen due to its linear fashion over time" (Warren 2017). In theory, choosing a different progression regimen (e.g. progress by only 1,000 feet per week or in two 6,000 feet steps) could thus yield different training outcomes.

Figure 2: In a small-scale study by Laurel et al. the use of an elevation training mask did not augment the pre-post-test time-trial performance (not shown) and it messed with the subjects' resting heart rate, which improved in the control and deteriorated (albeit not significantly) in the experimental condition (Lauren 2015).

In view of the fact that a study from the University of Texas at Arlington in 18-35 year-old volunteers saw detrimental, not beneficial effects on their resting heart rate and thus one of the measured indices of adaptation when they used an Elevation Training Mask 2.0 to simulate high altitude train from the ranges of 3000 feet to 18,000 feet above sea level, either, I do yet have my doubts that the null result in Warren's study is a consequence of a suboptimal progression strategy.

If there's a chance that the masks are more than a fashion gimmick, ...

this has to be a 'side effect' of a potential training effect the masks could have on your inspiratory muscle (learn more about inspiratory muscle training aka "IMT"). Even though, the evidence that the musculature you use to suck in the air is a bottleneck for athletic performance is ambiguous and studies such as William et al. (2002) or Inbar et al. who had their well-trained endurance athletes use a special threshold inspiratory muscle trainer for 0.5 h x d(-1) six times a week for 10 weeks found no performance increases, in spite of significant increases in inspiratory muscle performance, there are also studies that suggest beneficial effects on exercise performance in noobs and pro-athletes:

• Chatham, et al. who report reduced levels of breathlessness, and increase in predicted (not measured) VO2 max in healthy, but untrained subjects after 10 weeks and 30 Tests of Incremental Respiratory Endurance (TIRE) set at 80% of peak.
• Volianitis et al. 2001 who found an increase in the distance those of the 14 female competitive rowers who had been randomly assigned to the active treatment covered in a 5 min all-out rowing test, as well as an increase in time-trial performance after 11 weeks of twice daily inspiratory muscle training on a specifically designed device.
• Romer et al. 2002 who observed that inspiratory muscle training attenuates the perceptual response to maximal incremental exercise and a marginally higher increase in 20 and 40km time-trial performance in 16 healthy trained male road cyclists.
• Enright et al. 2006 who observed non-specified (full text not available) increases "exercise capacity in people who are healthy", but previously untrained in response to an 8-week program of IMT set at 80% of maximal effort. 

Even though these studies would suggest that inspiratory muscle training could yield performance increments, it is by no means clear if these effects could be triggered by the use of an "elevation masks". The resistance of these devices is, after all, much lower than the one you'd experience with one of the specifically designed IMT devices. Moreover, if this 'side effect' of the failed alternative to altitude training existed, we should have seen some effects in the previously cited studies by Warren and Lauren, too. Personally, I would thus not put too much faith in a conceivable cross-over effect of wearing an "elevation mask" even the producers of such devices apparently haven't thought about yet.
References:

• Chatham, K., et al. "Inspiratory muscle training improves shuttle run performance in healthy subjects." Physiotherapy 85.12 (1999): 676-683.
• Enright, Stephanie J., et al. "Effect of high-intensity inspiratory muscle training on lung volumes, diaphragm thickness, and exercise capacity in subjects who are healthy." Physical therapy 86.3 (2006): 345.
• Inbar, Omri, et al. "Specific inspiratory muscle training in well-trained endurance athletes." Medicine and Science in Sports and Exercise 32.7 (2000): 1233-1237.
• Lauren, Bryan, et al. "Physiological Change Through Aerobic Exercise Under Hypoxic Conditions With An Elevation Mask." (2015).
• Romer, Lee M., Alison K. McConnell, and David A. Jones. "Effects of inspiratory muscle training on time-trial performance in trained cyclists." Journal of sports sciences 20.7 (2002): 547-590.
• Volianitis, Stefanos, et al. "Inspiratory muscle training improves rowing performance." (2001).
• Warren, Brian G., Frank Spaniol, and Randy Bonnette. "The effects of an elevation training mask on VO2Max of male reserve officers training corps cadets." International Journal of Exercise Science 10.1 (2017): 4.
• Williams, James S., et al. "Inspiratory muscle training fails to improve endurance capacity in athletes." Medicine and Science in Sports and Exercise 34.7 (2002): 1194-1198.