Box breathing does not have consistent evidence behind it as a recovery booster after hard training. A 2025 study in PLOS ONE found the technique performed no better — and by some measures worse — than slower paced breathing after high-intensity intervals in physically active young adults. A 2026 study in military cadets found the opposite for one recovery marker. The evidence disagrees, and the population studied matters.
What box breathing actually is
Box breathing is a paced-breathing pattern: inhale for a slow count, hold, exhale for the same count, hold again, then repeat. The most common version uses a four-count for each of the four phases, which is where the "box" name comes from. It's a form of what the National Institutes of Health's National Center for Complementary and Integrative Health calls diaphragmatic or paced breathing — slow, deliberate breaths meant to shift the nervous system out of a stressed state. Per that agency, a 2019 research review found diaphragmatic breathing exercises "may help to reduce stress," with measurable changes in cortisol and blood pressure in some studies. That's a general stress-reduction finding, not a workout-recovery one — which is where the newer sports-science research comes in.
What happens to recovery after a hard workout?
After intense exercise, the body needs the parasympathetic ("rest and digest") branch of the nervous system to reassert itself over the sympathetic ("fight or flight") branch that dominated during the effort. Researchers track this shift with heart rate recovery — how fast heart rate drops in the minutes after exercise stops — and with heart rate variability (HRV), a measure of the variation between heartbeats that tends to rise as the parasympathetic system regains control. Slower, paced breathing is a plausible lever for speeding that shift along, which is why both studies below tested it directly after strenuous exercise rather than at rest.
The case against: the PLOS ONE 2025 study
Researchers Murat Kasap and Gökhan Recep Aydin had 40 physically active university students complete 15-minute high-intensity cycling intervals, then recover using one of three breathing patterns: normal spontaneous breathing, box breathing on a 4-4-4-4 count, or a slower six-breaths-per-minute pattern. The six-breaths-per-minute group came out ahead. Box breathing left participants with significantly higher post-exercise heart rates (about 165 beats per minute versus about 155) and higher perceived exertion scores than the six-breaths-per-minute group. Time to full recovery didn't differ significantly between any of the three groups. The authors' interpretation: at that pace, the breath-holds built into box breathing may add a mild physiological load right when the body is trying to calm down, making it a less efficient recovery tool than simply breathing slowly without the holds.
The case for: the tactical-athlete study
A separate study, led by Mark Jones and colleagues and set for publication in Medicine & Science in Sports & Exercise in 2026, tells a different story for a different group. It tested 62 military cadets after maximal exertion, comparing box breathing, a related technique called cyclic sighing, and spontaneous breathing as a control. Both structured breathing methods produced significantly greater increases in a marker of parasympathetic recovery (high-frequency HRV) than the control group. Heart rate recovery itself improved for everyone over the three minutes after exercise, with no significant difference between groups on that specific measure. The authors framed both techniques as "field-ready" tools for a population — cadets under sustained physical and operational stress — that's meaningfully different from recreational exercisers doing cardio intervals.
Why the findings disagree
Neither study is wrong; they measured different things in different people. The PLOS ONE study compared box breathing against another active breathing protocol and focused on heart rate and perceived exertion in recreational exercisers. The tactical-athlete study compared box breathing against doing nothing structured and focused on an HRV submeasure in a younger, highly conditioned military population. Put together, the honest read is: box breathing isn't proven to out-recover simple slow breathing without holds, but it may still beat not doing any structured breathing at all — and neither study has been replicated at scale. Anyone selling box breathing as a guaranteed recovery hack is outrunning what these two studies actually show.
What about stress, not just recovery?
Recovery from a single workout is a narrower question than stress management. Per the agency, slow breathing exercises more broadly have modestly better-supported evidence for lowering blood pressure — a 2019 review of 17 studies covering 1,165 people found a modest blood-pressure reduction from slow breathing, enough that it calls slow breathing "a reasonable first treatment" for people with prehypertension or low-risk high blood pressure. That's a separate claim from workout recovery, and it's worth keeping the two apart: the case for paced breathing as everyday stress management is on firmer ground than the case for box breathing specifically as a post-workout recovery tool.
How to try it after a workout
- Sit or stand tall, feet flat, shoulders relaxed, once the workout itself is finished.
- Inhale through the nose for a slow count of four.
- Hold the breath, without straining, for a count of four.
- Exhale slowly through the nose or pursed lips for a count of four.
- Hold again for a count of four, then repeat for two to five minutes.
If the four-count holds feel effortful rather than calming — which is roughly what the PLOS ONE participants reported — drop the holds and simply breathe in and out slowly on a five-second count each way. That pattern is closer to what performed best in the recovery study.
When to see a professional
Breath-holding is generally safe for healthy adults, but relaxation techniques that involve altered breathing carry rare reports of problems for people with epilepsy, certain psychiatric conditions, or a trauma history, per the same NIH agency's guidance. Anyone with a diagnosed heart or lung condition, or who feels dizzy or short of breath during paced breathing, should check with a doctor before making it a regular practice. This article is informational and not a substitute for medical advice.
For a related nutrition perspective, read How Much Protein Do Active Adults Actually Need?.
For more context, read Complete Guide to Building a Sustainable Wellness Routine.
For more context, read Does the post-workout anabolic window actually exist?.
For more context, read Skin Cycling, Explained by the Dermatologist Who Named It.