Nasal breathing during training offers several performance and health benefits that can improve conditioning, recovery, and mental focus. Here's the rub - It’s hard at first. Nasal-only training takes patience and consistency, and it often feels uncomfortable in the beginning. But over time, your body will adapt to this new stress and take your fitness levels to another level.
It's a simple, no-cost way to enhance breathing efficiency, build aerobic capacity, and sharpen mental toughness. Unlike mouth breathing, nasal breathing filters, warms, and humidifies the air before it enters the lungs. This reduces irritation and improves oxygen uptake efficiency (Niinimaa et al., 1980) and helps to suppress the sympathetic neural drive associated with mouth breathing. The slower, more controlled breathing pattern through the nose encourages better diaphragmatic activation, which helps stabilize the core and improve posture (McKeown, 2015).
From a metabolic standpoint, nasal breathing helps athletes stay in an aerobic state longer. This is important for endurance and conditioning work, where staying below the anaerobic threshold delays fatigue. It also promotes better carbon dioxide tolerance, which improves VO₂ max and endurance over time (Dallam et al., 2018). Research has shown that trained individuals using nasal-only breathing can maintain similar work output with lower heart and respiratory rates than when mouth breathing (Morton et al., 1995).
Nasal breathing also supports parasympathetic nervous system activation, leading to better calm and focus during training. This helps reduce stress hormones like cortisol and supports faster recovery between sessions (Jerath et al., 2006). Athletes report feeling more in control and less “gassed” once nasal breathing becomes natural. While it may feel like you are taking a step backwards in the early stages of nasal breathing only during exercise, the long term benefits will far outweigh the short term drawbacks.
Sources:
Dallam, G. M., Jonas, S., & Miller, T. (2018). Effect of nasal versus oral breathing on VO2max and running performance in competitive runners. International Journal of Kinesiology and Sports Science, 6(2), 22–27.
Jerath, R., Edry, J. W., Barnes, V. A., & Jerath, V. (2006). Physiology of long pranayamic breathing: Neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical Hypotheses, 67(3), 566–571.
McKeown, P. (2015). The Oxygen Advantage. HarperOne.
Morton, A. R., King, K., Papalia, S., Goodman, C., Turley, K. R., & Wilmore, J. H. (1995). Comparison of maximal oxygen consumption with oral and nasal breathing. Australian Journal of Science and Medicine in Sport, 27(3), 51–55.
Niinimaa, V., Cole, P., Mintz, S., & Shephard, R. J. (1980). Oronasal distribution of respiratory airflow. Respiration Physiology, 42(1), 25–32.