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How Should I Breathe While Running?

Learn how to breathe efficiently while running, when to use nose vs mouth breathing, and how breathing affects performance and heart rate.

How should I breathe while running?

Breathing is one of the most common things runners worry about—and one of the most misunderstood. The good news is that you don’t need a complex technique or rigid rules. Your body is already very good at matching breathing to effort. The goal is simply to breathe deeply, relaxed, and in sync with your pace.

Understanding a few basic principles can help you feel more comfortable, delay fatigue, and avoid common problems like side stitches or early breathlessness.

Breathe deep, not shallow

When runners feel out of breath, it’s often because breathing becomes shallow and rapid, driven mostly by the upper chest. This limits how much air reaches the lungs and can increase the sensation of panic or tightness.

Instead, aim for diaphragmatic breathing, where the diaphragm and lower rib cage expand on the inhale. This allows more air to enter the lungs with less effort and improves ventilatory efficiency. Research shows that diaphragmatic breathing can reduce oxygen cost and improve breathing economy during exercise (Kiesel et al., 2018).

Simple cue: keep your shoulders relaxed and let your ribs expand outward as you inhale.

Nose vs mouth breathing: match it to intensity

There’s no single “correct” way to breathe through your nose or mouth—it depends on how hard you’re running.

  • Easy runs: Nasal breathing works well and naturally limits intensity. If you can breathe comfortably through your nose, you’re likely running at an aerobic, sustainable effort.
  • Moderate to hard runs: As intensity increases, your body needs more oxygen. Mouth or combined nose-mouth breathing allows higher ventilation and is more effective at higher workloads.

Studies comparing nasal and oral breathing show that mouth breathing supports greater oxygen uptake during intense exercise, which is why most runners switch instinctively (Dallam et al., 2018).

If forcing nose-only breathing makes you tense or dizzy, don’t fight it—open your mouth and stay relaxed.

Use rhythmic breathing to stay relaxed

Many runners find it helpful to synchronize breathing with their steps. This doesn’t improve oxygen delivery directly, but it promotes consistency and prevents breath-holding.

Common patterns include:

  • Easy pace: inhale for 3 steps, exhale for 3 steps (3:3)
  • Steady pace: 3:2
  • Hard efforts: 2:1 or 2:2

Longer exhales can also help reduce side stitches by relaxing the diaphragm and abdominal muscles.

Why breathing can feel like the limiter

During hard or prolonged running, the muscles responsible for breathing can fatigue just like your legs. Research shows that respiratory muscle fatigue can increase perceived effort and influence blood flow distribution during intense exercise (Harms et al., 1997).

In well-trained runners, very high-intensity efforts can even lead to a temporary drop in blood oxygen levels, known as exercise-induced arterial hypoxemia. This is normal in some athletes and helps explain why maximal efforts often feel limited by breathing rather than leg strength (Dempsey & Wagner, 1999).

Can you train your breathing?

Specific respiratory muscle training (such as inspiratory muscle trainers) has been shown in multiple studies to produce small but meaningful improvements in endurance performance and perceived effort. While not essential for most runners, it can be useful for those doing frequent high-intensity or long-distance training (Illi et al., 2012).

For most runners, however, the biggest gains come from:

  • Running at appropriate intensities
  • Staying relaxed
  • Letting breathing respond naturally to pace

Key takeaway

There’s no perfect breathing technique. Breathe deeply, stay relaxed, use your mouth when needed, and let your breathing reflect how hard you’re running. If breathing feels smooth, your pacing is probably right.

References

  • Dallam, G. M., et al. (2018). Effect of nasal versus oral breathing on exercise performance. Journal of Strength and Conditioning Research.
  • Dempsey, J. A., & Wagner, P. D. (1999). Exercise-induced arterial hypoxemia. Journal of Applied Physiology.
  • Harms, C. A., et al. (1997). Respiratory muscle work compromises leg blood flow during maximal exercise. Journal of Applied Physiology.
  • Illi, S. K., et al. (2012). Effect of respiratory muscle training on exercise performance in healthy individuals. Sports Medicine.
  • Kiesel, K., et al. (2018). Diaphragmatic breathing and functional movement. International Journal of Sports Physical Therapy.