Endurance athletes across the globe are always looking for a way to gain an edge on their opponents. Some methods that have been adopted by elite and amateur athletes alike are altitude and respiratory muscle training. Altitude training involves training at high altitudes where oxygen is more limited than at sea level. Respiratory muscle training involves strengthening the muscles that are required for breathing. Both types of training involve creating a hypoxic condition for the body, meaning that the tissues are not receiving an adequate supply of oxygen. Exposure to hypoxic conditions stimulates the production of erythropoietin in the kidneys, which increases production of red blood cells. This creates an increase in the oxygen carrying capacity of the blood and has been correlated to an increase in endurance performance [1].These training techniques are said to increase aerobic capacity (VO2max), endurance, lung function, and overall performance in athletes [2]. 

Respiratory muscle training can be done using an elevation mask, which is designed to simulate the conditions of training at altitude while training at sea level (figure 1). Elevation masks cover the nose and mouth, restricting air flow and making respiration more difficult for the athlete. They often have values that allow for adjustments to the amount of oxygen that enters the mask. The Elevation Mask 2.0 by Training Mask LLC is one type of mask that uses values and can simulate altitudes ranging from 914 m to 5486 m [2]. But the question is – do these masks really cause physiological changes in the body to improve stamina and endurance?

Figure 1. The Elevation Mask 2.0 (Training Mask LLC, Cadillac Michigan) that can be used by athletes during training in hopes of improving performance [2]. It consists of a silicone mask and neoprene head strap, with adjustable resistance caps to change the amount of air flow.

Many studies have attempted to test these masks and determine if respiratory muscle training is actually beneficial to endurance athletes. Acclimating to high altitude occurs as the body increases the amount of red blood cells, which has been shown to improve sea-level running performance [1]. However, this hematological effect has not been consistently shown in studies that used elevation training masks. In addition to the volume of red blood cells, significant changes have not been observed in blood lactate concentration in people wearing the mask during training. These trends indicate that elevation masks may work as respiratory muscle training devices but do not accurately simulate the physiological changes that occur in the body at high altitudes [2]. 

Increased aerobic capacity, or ability to pump oxygenated blood to the muscles during exercise, is one of the main goals of endurance training. By participating in any sort of endurance training program, VO2max can be improved as the body adapts to the demands being placed on it. However, the goal of altitude and respiratory muscle training is to further enhance this ability to reach peak performance levels. Studies have shown that increases in VO2max for groups wearing a mask compared to increases in control groups are not significant [2]. In contrast, ventilatory threshold, which refers to the point during exercise where the rate of ventilation increases faster than the rate of oxygen uptake, and power output show a significant increase in experimental groups wearing a mask compared to control groups [3]. These findings indicate that wearing the elevation mask may help improve the function of the cardiovascular system during exercise.

Ventilatory threshold (VT) has been shown to correlate to the amount of work the muscles can maintain without fatigue. When the VT is surpassed, the muscles do not receive the necessary amount of oxygen and fatigue begins to set in. Therefore, increasing the VT for an endurance athlete should result in better performance [4]. In addition to endurance based metrics, respiratory muscle training has been shown to improve deep breathing and increase ventilatory efficiency throughout exercise[3,5]. 

Although there seems to be trends present in studies involving elevation masks and endurance training, there are limitations to what can be concluded. Most of the studies evaluated had limited sample sizes and the duration and intensity of the exercise regimes varied between studies. However, the studies do seem to imply that elevation masks may be beneficial to endurance performance through respiratory muscle training. By making it more difficult for the athlete to inhale and exhale, the body does appear to undergo physiological changes to adapt to the lower levels of oxygen. This adaptation may result in increased VO2max, VT, and power output over time. It seems that using an elevation mask does not cause any of the hematological changes in the body that occur when a person actually reaches a higher altitude. So although endurance performance may increase as a result of using the mask, it does not directly mimic the conditions of elevation training.

Questions to Consider:

• Prior to reading this article, had you heard of professional athletes using altitude training or elevation masks to improve their performance? And if so, what sport did these athletes participate in?
• Do you think amateur athletes and non-athletes could benefit from using an elevation mask in daily life?
• Have you ever experienced altitude sickness? If so, what symptoms did you have?

References:

1. de Paula, P., Niebauer, J. (2012). Effects of high altitude training on exercise capacity: fact or myth. Sleep Breath 16, 233–239. https://doi.org/10.1007/s11325-010-0445-1
2. Porcari, J. P., Probst, L., Forrester, K., Doberstein, S., Foster, C., Cress, M. L., & Schmidt, K. (2016). Effect of Wearing the Elevation Training Mask on Aerobic Capacity, Lung Function, and Hematological Variables. Journal of sports science & medicine, 15(2), 379–386.
3. Kido, S., Nakajima, Y., Miyasaka, T., Maeda, Y., Tanaka, T., Yu, W., Maruoka, H., & Takayanagi, K. (2013). Effects of combined training with breathing resistance and sustained physical exertion to improve endurance capacity and respiratory muscle function in healthy young adults. Journal of physical therapy science 25(5), 605–610. https://doi.org/10.1589/jpts.25.605
4. Graef, J.L., Smith, A.E., Kendall, K.L. et al. (2008). The relationships among endurance performance measures as estimated from VO2PEAK, ventilatory threshold, and electromyographic fatigue threshold: a relationship design. Dyn Med 7(15). https://doi.org/10.1186/1476-5918-7-15
5. Granados, J., Gillum, T., Castillo, W., Christmas, K., Kuennen, M. (2016). “Functional” Respiratory Muscle Training During Endurance Exercise Causes Modest Hypoxemia but Overall is Well Tolerated. Journal of Strength & Conditioning Research 30(3), 755-762.