Diaphragmatic Breathing: The Complete Guide

How to do it, what your diaphragm is actually doing, and an honest read of the evidence — including the central question about this technique that no study has answered.

Jay Newmark 7 min read Last updated August 2026
by
Key Points
  • Diaphragmatic breathing means letting the diaphragm, rather than the chest and shoulders, drive the breath. The mechanics are not in dispute and the muscle really does move the abdominal wall outward
  • Breathing slowly has a well-measured acute effect: vagal tone rises, the baroreflex sharpens, blood pressure falls during the session
  • What has never been tested is whether the diaphragmatic part is the active ingredient, or whether it is simply a reliable way to get someone to breathe slowly
  • The best-designed trial in the field put slow breathing against a matched breathing placebo in 400 people and found no advantage at all
  • About a third of beginners drop their carbon dioxide into the clinically low range on day one. That is the lightheadedness, and it resolves within a week

What Diaphragmatic Breathing Is

The diaphragm is a dome of muscle and tendon separating the chest from the abdomen. When it contracts it flattens downward, the chest cavity gets bigger, pressure drops, and air moves in. It also presses on the organs below it, which have nowhere to go but forward — so the abdominal wall moves out. When it relaxes it domes back up and the wall settles.

That much is not controversial. The two-compartment model of the chest wall that describes it was established in 1967 and has underpinned respiratory measurement ever since.1 “Belly breathing” is not a metaphor. The belly moves, and it moves because the diaphragm pushed on it. Chest breathing is the alternative pattern: the ribcage and the muscles of the neck and upper chest do more of the lifting, and the abdominal wall stays comparatively still.

Two things follow, and they shape the rest of this page. The first is that diaphragmatic breathing belongs to a family — slow-paced breathing — and almost all the research cited for it was done on the family rather than on the abdominal mechanics. The second is that the mechanics are the one thing genuinely distinguishing it, and nobody has ever tested them against the obvious control.

How Much of a Breath Is the Diaphragm

You will read almost everywhere that the diaphragm does 70 to 80 percent of the work of breathing. We cannot find a measurement behind that number. What the measurement literature actually reports is lower, and far more variable between people.

SourceAbdominal share of a quiet breathWhat it measured
Konno and Mead, 19671Strongly posture-dependentThe original two-compartment method. Established that the split shifts with position and varies widely between individuals
Jakobson and Ivarsson, 1977264 percent, range 39 to 76Ten healthy men, semi-recumbent. The range is the finding, not the average
Romagnoli et al., 2008363 percent, plus or minus 11Optoelectronic plethysmography, a considerably more precise method. Healthy subjects

So the diaphragm does most of the work, and the general point stands. But the spread between individuals runs from under 40 percent to over 75, and the share falls when you sit or stand rather than lie down. Anyone telling you there is one correct percentage, or that yours is wrong, is working from a number that does not exist.

How to Do Diaphragmatic Breathing

  1. Lie down, at least at first. On your back, knees bent, feet flat. Gravity makes the abdominal movement easier to feel. A supported chair works once you know what you are looking for.
  2. One hand on the chest, one on the abdomen. Just below the navel. This is the entire feedback system and it is better than any app.
  3. Exhale everything first. Through the mouth, until the breath ends on its own. Do not force the bottom of it.
  4. Inhale through the nose for four. Aim the breath low. The lower hand should move first and move more; the upper hand should stay nearly still. If the chest rises first, reset and start the breath again.
  5. Pause a second at the top, then exhale for five or six. Through the nose or slightly pursed lips, whichever you control better. Steady the whole way out.
  6. Repeat for five to ten minutes. That lands at roughly five or six breaths a minute, which is where the cardiovascular effects below are most reliably produced.

The most common beginner error is not breathing wrong, it is breathing too big. Slowing the rate while enlarging every breath means you ventilate more than usual and blow off carbon dioxide, which is what produces the lightheadedness.4 Slow the rate, keep the breath comfortable. The timer in the sidebar paces it for you, and the coherent breathing pacer runs 5.5 seconds in and 5.5 out.

What the Evidence Actually Shows

Diaphragmatic breathing is well studied as a member of the slow-breathing family and barely studied on its own. The broadest pooled estimate available is a meta-analysis of breathwork trials generally, which found small-to-medium benefits for stress, anxiety and depression while warning against “a miscalibration between hype and evidence.”5 Below, each claim is rated against research that tested that claim.

Claim Verdict What the Research Actually Says
The diaphragm descends and pushes the abdominal wall outward Supported The two-compartment model of the chest wall, established in 1967 and the basis of respiratory measurement since, describes exactly this: diaphragmatic contraction displaces the abdominal contents caudally and the abdominal wall moves outward.1
The abdomen moves most of the air in a quiet breath Qualified Measured at 64 percent in ten semi-recumbent men, with individuals ranging from 39 to 76 percent,2 and at 63 percent plus or minus 11 by optoelectronic plethysmography.3 It falls further when upright. The widely repeated 70 to 80 percent figure is not traceable to a measurement.
Breathing at about six a minute raises heart rate variability while you do it Supported A systematic review and meta-analysis covering 223 studies found consistent increases in vagally mediated heart rate variability during slow breathing and immediately after it.6 This is a state change measured while you practice, not evidence about resting physiology.
Slow breathing improves baroreflex sensitivity and lowers blood pressure during a session Supported Fifteen minutes of paced breathing at six a minute raised baroreflex sensitivity from 5.8 to 10.3 ms/mmHg in hypertensive adults and from 10.9 to 16.0 in controls, with systolic pressure falling about 9 mmHg during the session.7
Practicing it reduces measured stress markers compared with no practice Qualified In 40 healthy adults doing twenty coached, device-guided sessions over eight weeks at about 3.5 breaths a minute, salivary cortisol fell significantly while controls did not move.8 The control group was passive, with no sham breathing, and the authors state there is no reference criterion establishing the cortisol change is clinically meaningful. The systematic review built on it grades the physiological evidence LOW across three studies.9
It beats another breathing pattern delivered with equal care Not Shown Four hundred participants, four weeks, ten minutes a day. The active arm breathed at 5.5 a minute; the placebo arm did a matched breathwork practice at 12 a minute with identical guidance, duration and ratio, rated equally credible by participants. On the primary stress outcome, F(1,377) = 0.089, p = 0.765. No difference on anxiety, depression, wellbeing or sleep.10
The diaphragmatic emphasis, rather than the slow rate, is the active ingredient Not Shown Testing this requires comparing abdominal-led against thoracic breathing at matched rate, volume and ratio. No such trial exists. The dedicated systematic review found only three eligible studies in the whole literature and noted that they do not even define the technique consistently;9 a narrative review makes the same complaint about standardization.11
A longer exhale than inhale is necessary for the heart rate variability effect Not Shown Two within-subject studies compared 1:1 against 1:2 inhale-to-exhale at a matched six breaths a minute and found no difference on any time- or frequency-domain HRV metric. The authors recommend clinicians simplify to 1:1.12
Your individual resonance frequency works better than a fixed six a minute Not Shown A four-week randomized comparison of individually tuned resonance frequency against a fixed 0.1 Hz found no meaningful difference between them on stress, anxiety or depression — and no improvement in resting HRV in any arm, including the group practicing daily.13
It durably lowers blood pressure Not Shown A meta-analysis of 15 trials found pooled reductions of 7.06 mmHg systolic,14 which is the figure usually quoted. But a much larger analysis restricted to hypertensive patients — 22 studies, over 17,000 participants — found device-guided slow breathing did not significantly beat usual care: systolic difference −2.13 mmHg, 95% CI −12.71 to +8.44, heterogeneity 93 percent.15 Durability after practice stops is unaddressed. The narrative review most often cited here performs no meta-analysis at all.16
Practicing it improves athletic performance Not Shown The athletic literature is about inspiratory muscle training — breathing against calibrated resistance, or sustained voluntary hyperpnea — which is strength training for the inhalation muscles, not slow diaphragmatic practice. Even there, a meta-analysis of 21 trials found no effect on VO₂max across 13 studies, and no differences against sham or placebo comparisons.17
Practice changes how you breathe when you are not thinking about it Not Shown Never measured in healthy adults. The only randomized trial to test whether training carries over into natural, uncued breathing studied COPD patients, whose starting mechanics are abnormal enough that the result does not transfer.18 Specific timelines like four to eight weeks have no evidential basis we can find.

The seventh row is the one worth sitting with, because it is the premise of the entire technique. Every breathing parameter that has been isolated and tested has come back null. The one parameter nobody has isolated is the diaphragmatic one.

Why It Works, and What That Does Not Prove

The mechanism is not mysterious. Breathing at around six a minute puts the respiratory rhythm in phase with the natural oscillation of the baroreflex, the loop adjusting heart rate in response to blood pressure. At that frequency heart rate and blood pressure oscillate roughly 180 degrees out of phase and the swings in heart rate get very large — the resonance effect.19 In a three-arm experiment with 95 participants, those breathing at their resonance frequency had better mood and lower systolic pressure under a stress task than a quiet-sitting group, or a group breathing just one breath a minute faster.20

Teaching Cue Is Not Active Ingredient

Putting a hand on your abdomen is a reliable, tactile way to get someone breathing slowly without hauling on their neck muscles. That is genuinely useful. It is a different claim from the diaphragmatic mechanics being what produces the benefit, and that second claim has never been tested against a rate-matched control.911 A review of 58 studies of breathing practices for stress concluded that once fast-breathing protocols are excluded, specific breath pace was not associated with effectiveness at all.21 Most breathing content treats the cue and the mechanism as the same thing, which is how a plausible story gets sold as a proven result.

There is a second wrinkle. The individual resonance frequency is not a stable personal constant — retesting people a week later found it had moved in two thirds of them.22 Which is one reason a fixed six a minute works about as well as a tailored figure, and why the personalization sold with some devices is doing less than it appears.

When Something Else Is the Better Choice

Diaphragmatic breathing is a good default and a poor universal. Three situations where the research points elsewhere:

  • You want a structure you will actually remember. Box breathing is symmetrical and easy to pace without a device. Diaphragmatic breathing gives you mechanics but no count, and a lot of people drift without one.
  • You want the rate the literature converges on. Coherence breathing at 5.5 a minute targets the one parameter with direct experimental support, and drops the scaffolding entirely.
  • You need to perform a task well immediately afterward. A systematic review of brief interventions for state anxiety found breathing-based approaches performed worst and most inconsistently of the categories compared, behind embodiment techniques and cognitive reappraisal.23

Where diaphragmatic breathing genuinely earns its place is as the foundation the others assume. Box breathing and 4-7-8 both take the mechanics for granted and add timing on top. Learning the mechanics first is why the count works when you get to it.

Safety and What to Expect Early On

The First Week Is the Worst

Sixteen people did ten minutes a day of paced breathing at six a minute. On day one, 37.5 percent dropped their end-tidal carbon dioxide below 30 mmHg — the clinical threshold for hypocapnia — during nothing more exotic than standard paced breathing. By day seven essentially none did, with no instruction given about it. They simply got better at the task.4

So expect lightheadedness, tingling in the hands or around the mouth, or a vague unease. If it happens, breathe less deeply rather than stopping altogether — the fix is smaller breaths, not a faster rate.

Separately: some people, particularly those with an anxiety disorder, get more anxious attempting to relax deliberately. This is documented, has its own literature going back to the 1980s, and slowed diaphragmatic breathing is among the techniques that provoke it.24 It is a known reaction, not a personal failing, and it is a reason to change approach rather than push through.

Worth knowing how rarely any of this gets measured. A systematic review of adverse events across meditation and breath-focused practices found a pooled rate of 8.3 percent in trials, rising to 33 percent in observational studies that actually asked participants.25 A nine-fold gap between the two mostly tells you that trials are not asking.

Building the Habit

Ten minutes a day is a reasonable target, and it is worth being clear that this is a practical recommendation rather than an evidence-based one — the largest meta-analysis found no dose-response relationship for duration, frequency or number of sessions.5 Nobody knows the right dose.

Start lying down, move to sitting once the movement is easy to feel, then to standing. Slow the rate before you deepen the breath. And do not expect it to rewrite how you breathe the rest of the day — you will get noticeably better at the exercise within a week or two, but whether that carries into unconscious resting breathing has never been measured in healthy people.18

Common Questions


Is diaphragmatic breathing the same as deep breathing?

No, and conflating them is what causes the lightheadedness. Deep breathing describes the volume of each breath. Diaphragmatic breathing describes which muscles move the air. You can breathe diaphragmatically at completely ordinary volume, and that is usually what you want — deliberately large breaths at a slow rate increase your total ventilation and drop your carbon dioxide.4


Why is this page rated Qualified rather than Well Supported?

Because the rating applies to the claim the page makes, not to the general idea of breathing slowly. The mechanics are solid and the acute cardiovascular physiology is solid. But the specific claim that the diaphragmatic emphasis is what produces the benefit has never been tested against a rate-matched control, and the outcome claims mostly fail against an active comparator. Qualified is the ceiling until someone runs that trial.


If the placebo trial was null, why do this at all?

Because “no better than a well-designed breathwork placebo” is not the same as “does nothing” — both arms of that trial improved.10 Ten minutes of sitting quietly with a structured task you believe in is a real intervention, even if the mechanism is not the one on the label. It is free, the downside is small and well characterized, and it does not require believing anything untrue about your diaphragm.


Belly breathing, abdominal breathing, diaphragmatic breathing — what is the difference?

Nothing. Two of those names describe what you can see and one describes what is causing it. The inconsistency is not harmless, though: the systematic review on this technique specifically flagged that studies do not define it the same way, which is part of why the evidence base is so thin.9


Can I do it while exercising?

At low to moderate intensity, yes. As intensity rises the accessory muscles necessarily engage, because demand exceeds what the diaphragm can supply alone. That is normal physiology rather than a technique failure. Note that breathing training marketed to athletes is usually inspiratory muscle training, which is a different intervention entirely.17


Does it help during a panic attack?

It can slow the hyperventilation component, which is a real part of the experience, and it is far more useful as something already practiced than as something attempted for the first time mid-episode. Be aware that some people find deliberate relaxation increases anxiety rather than reducing it, and that this is more common in people with anxiety disorders.24 Anyone getting recurrent panic attacks should be talking to a clinician rather than managing alone.


Is there better evidence for heart rate variability biofeedback?

Somewhat, but less than its reputation suggests. The most recent meta-analysis of remote HRV biofeedback, covering 18 studies and 1,352 participants, found a significant effect on depression but no significant effect on stress.26 The earlier and much-quoted large effect sizes came from a smaller literature with mostly inactive controls.


The Short Answer

Diaphragmatic breathing is a good way to learn to breathe slowly. The mechanism is real, the acute effect on your cardiovascular system is real and measurable, and a hand on the abdomen is the most reliable teaching cue anyone has found. What it is not is a proven intervention with a known dose, a known timeline and a demonstrated mechanism. The parameter that matters appears to be the rate. The diaphragmatic part has never been isolated and tested, and the best-controlled trial in the field found no advantage over a credible placebo.

Ten minutes a day, slower rather than deeper, on the understanding that some of what it does is sitting quietly for ten minutes. That is a fair trade, and an honest description of it.

Practice It

Slow breathing at 5.5 a minute, paced for you. Free, no account, nothing saved.

Open the Coherent Breathing Pacer ›
References
  1. Konno, K., and Mead, J. (1967). Measurement of the separate volume changes of rib cage and abdomen during breathing. Journal of Applied Physiology, 22(3), 407–422. doi:10.1152/jappl.1967.22.3.407
  2. Jakobson, S., and Ivarsson, I. (1977). Thoraco-abdominal perimetry for partitioning of the tidal volume into fractions due to rib cage expansion and diaphragmatic descent. Upsala Journal of Medical Sciences, 82(1), 31–37. doi:10.3109/03009737709179056
  3. Romagnoli, I., Lanini, B., Binazzi, B., et al. (2008). Optoelectronic plethysmography has improved our knowledge of respiratory physiology and pathophysiology. Sensors, 8(12), 7951–7972. doi:10.3390/s8127951
  4. Szulczewski, M. T. (2019). Training of paced breathing at 0.1 Hz improves CO2 homeostasis and relaxation during a paced breathing task. PLoS One, 14(6), e0218550. doi:10.1371/journal.pone.0218550
  5. Fincham, G. W., Strauss, C., Montero-Marin, J., and Cavanagh, K. (2023). Effect of breathwork on stress and mental health: a meta-analysis of randomised-controlled trials. Scientific Reports, 13, 432. doi:10.1038/s41598-022-27247-y
  6. Laborde, S., Allen, M. S., Borges, U., et al. (2022). Effects of voluntary slow breathing on heart rate and heart rate variability: a systematic review and a meta-analysis. Neuroscience and Biobehavioral Reviews, 138, 104711. doi:10.1016/j.neubiorev.2022.104711
  7. Joseph, C. N., Porta, C., Casucci, G., et al. (2005). Slow breathing improves arterial baroreflex sensitivity and decreases blood pressure in essential hypertension. Hypertension, 46(4), 714–718. doi:10.1161/01.HYP.0000179581.68566.7d
  8. Ma, X., Yue, Z.-Q., Gong, Z.-Q., et al. (2017). The effect of diaphragmatic breathing on attention, negative affect and stress in healthy adults. Frontiers in Psychology, 8, 874. doi:10.3389/fpsyg.2017.00874
  9. Hopper, S. I., Murray, S. L., Ferrara, L. R., and Singleton, J. K. (2019). Effectiveness of diaphragmatic breathing for reducing physiological and psychological stress in adults: a quantitative systematic review. JBI Database of Systematic Reviews and Implementation Reports, 17(9), 1855–1876. doi:10.11124/JBISRIR-2017-003848 — three included studies, only one randomized, and GRADE certainty is low for every physiological outcome.
  10. Fincham, G. W., Strauss, C., and Cavanagh, K. (2023). Effect of coherent breathing on mental health and wellbeing: a randomised placebo-controlled trial. Scientific Reports, 13, 22141. doi:10.1038/s41598-023-49279-8
  11. Hamasaki, H. (2020). Effects of diaphragmatic breathing on health: a narrative review. Medicines, 7(10), 65. doi:10.3390/medicines7100065
  12. Meehan, Z. M., and Shaffer, F. (2024). Do longer exhalations increase HRV during slow-paced breathing? Applied Psychophysiology and Biofeedback, 49(3), 407–417. doi:10.1007/s10484-024-09637-2
  13. Sumińska, S., Rynkiewicz, A., and Szulczewski, M. (2026). Resonance frequency versus fixed 0.1 Hz breathing in HRV biofeedback: a four-week randomized comparison. Scientific Reports, 16(1), 22630. doi:10.1038/s41598-026-53333-6
  14. Garg, P., Mendiratta, A., Banga, A., et al. (2024). Effect of breathing exercises on blood pressure and heart rate: a systematic review and meta-analysis. International Journal of Cardiology Cardiovascular Risk and Prevention, 20, 200232. doi:10.1016/j.ijcrp.2023.200232
  15. de Freitas Gonçalves, K. S., Queiroz Godoy Daniel, A. C., Tatagiba Lamas, J. L., et al. (2022). Device and nondevice-guided slow breathing to reduce blood pressure in hypertensive patients: a systematic review and meta-analysis. Health Science Reports, 5(3), e636. doi:10.1002/hsr2.636
  16. Yau, K. K.-Y., and Loke, A. Y. (2021). Effects of diaphragmatic deep breathing exercises on prehypertensive or hypertensive adults: a literature review. Complementary Therapies in Clinical Practice, 43, 101315. doi:10.1016/j.ctcp.2021.101315 — a narrative review with no pooled effect. Any single millimetre figure attributed to it is wrong by construction.
  17. HajGhanbari, B., Yamabayashi, C., Buna, T. R., et al. (2013). Effects of respiratory muscle training on performance in athletes: a systematic review with meta-analyses. Journal of Strength and Conditioning Research, 27(6), 1643–1663. doi:10.1519/JSC.0b013e318269f73f
  18. Yamaguti, W. P., Claudino, R. C., Neto, A. P., et al. (2012). Diaphragmatic breathing training program improves abdominal motion during natural breathing in patients with chronic obstructive pulmonary disease: a randomized controlled trial. Archives of Physical Medicine and Rehabilitation, 93(4), 571–577. doi:10.1016/j.apmr.2011.11.026
  19. Lehrer, P. M., and Gevirtz, R. (2014). Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology, 5, 756. doi:10.3389/fpsyg.2014.00756
  20. Steffen, P. R., Austin, T., DeBarros, A., and Brown, T. (2017). The impact of resonance frequency breathing on measures of heart rate variability, blood pressure, and mood. Frontiers in Public Health, 5, 222. doi:10.3389/fpubh.2017.00222
  21. Bentley, T. G. K., D’Andrea-Penna, G., Rakic, M., et al. (2023). Breathing practices for stress and anxiety reduction: conceptual framework of implementation guidelines based on a systematic review of the published literature. Brain Sciences, 13(12), 1612. doi:10.3390/brainsci13121612
  22. Capdevila, L., Parrado, E., Ramos-Castro, J., Zapata-Lamana, R., and Lalanza, J. F. (2021). Resonance frequency is not always stable over time and could be related to the inter-beat interval. Scientific Reports, 11, 8400. doi:10.1038/s41598-021-87867-8
  23. Chin, P., Gorman, F., Beck, F., Russell, B. R., Stephan, K. E., and Harrison, O. K. (2024). A systematic review of brief respiratory, embodiment, cognitive, and mindfulness interventions to reduce state anxiety. Frontiers in Psychology, 15, 1412928. doi:10.3389/fpsyg.2024.1412928
  24. Newman, M. G., LaFreniere, L. S., and Jacobson, N. C. (2018). Relaxation-induced anxiety: effects of peak and trajectories of change on treatment outcome for generalized anxiety disorder. Psychotherapy Research, 28(4), 616–629. doi:10.1080/10503307.2016.1253891
  25. Farias, M., Maraldi, E., Wallenkampf, K. C., and Lucchetti, G. (2020). Adverse events in meditation practices and meditation-based therapies: a systematic review. Acta Psychiatrica Scandinavica, 142(5), 374–393. doi:10.1111/acps.13225
  26. Vann-Adibe, S., Tsui, H. K. H., Zhou, H. Q., Ciren, Z., Li, C., and Cha, S. K. W. (2025). Efficacy and methodology of remote heart rate variability biofeedback interventions for mental health: a systematic review and meta-analysis. Applied Psychophysiology and Biofeedback. doi:10.1007/s10484-025-09750-w — published online ahead of print, so no volume or page numbers yet.
  27. Finta, R., Nagy, E., and Bender, T. (2018). The effect of diaphragm training on lumbar stabilizer muscles: a new concept for improving segmental stability in the case of low back pain. Journal of Pain Research, 11, 3031–3045. doi:10.2147/JPR.S181610 — cited here for the correction above, not in support of any claim on this page.
JN
Jay Newmark

Jay Newmark is a health writer with a background in kinesiology and seven years covering sleep, stress, and performance science for digital health and fitness publications. He writes about breathwork from a science-first perspective.

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