When stress rises quickly, breathing is one of the few physiological processes people can consciously influence almost immediately. That has made techniques such as box breathing and prolonged-exhalation breathing increasingly popular among people looking for a fast way to manage pressure.
Now, new research from Texas State University offers experimental evidence that these techniques may do more than simply create a subjective feeling of calm.
A randomized controlled trial published in Comprehensive Psychoneuroendocrinology in June 2026 tested box breathing and prolonged-exhalation breathing immediately before and during a standardized psychological stress challenge. The study included 66 adults, divided equally among normal breathing, box breathing, and prolonged-exhalation groups. Researchers measured heart rate, state anxiety, heart-rate variability, salivary alpha-amylase, secretory immunoglobulin A, cortisol, and cognitive performance.
The results were notable but not universal. Both breathing techniques reduced several markers of acute stress compared with normal breathing. Heart rate, state anxiety, and salivary alpha-amylase showed the clearest differences. However, cortisol, heart-rate variability, and cognitive performance did not significantly differ between the groups.
That makes the study more interesting than a simple claim that “box breathing works.” It suggests that brief breathing exercises may influence some components of the body’s acute stress response while leaving others unchanged.
Why Researchers Are Testing Breathing Under Stress
Stress is not a single physiological event.
When someone encounters a threatening or demanding situation, the body can increase heart rate, alter breathing, mobilize energy, change attention, and activate multiple hormonal and immune pathways. These responses can be useful in the short term, but repeated or prolonged activation is associated with broader health risks.
This is why researchers increasingly study stress through several measurements at once.
A person may say they feel anxious while their heart rate rises. Salivary alpha-amylase may increase as sympathetic activity changes. Cortisol may respond on a different timeline. Heart-rate variability can provide another perspective on autonomic regulation.
The Texas State University study was designed around precisely this problem.
The research team included Matthew J. McAllister, M. Hunter Martaindale, Nate Sutton, and Judith P. Andersen, with McAllister, Martaindale, and Sutton affiliated with Texas State University’s Department of Health and Human Performance and Andersen affiliated with the University of Toronto Mississauga.
Rather than asking participants whether breathing exercises felt relaxing during an ordinary day, the researchers placed them in a controlled psychological stress situation and then examined how their bodies responded.
That distinction matters for stress management, because an intervention that feels relaxing in a quiet room may behave differently when someone is facing an actual stressor.
How the Experiment Worked
The study recruited 66 participants between 18 and 39 years old. They were randomly assigned to three groups:
| Group | Participants | Breathing Protocol |
|---|---|---|
| Normal breathing | 22 | Normal breathing |
| Box breathing | 22 | 4-second inhale, 4-second hold, 4-second exhale, 4-second hold |
| Prolonged exhalation | 22 | 3-second nasal inhale followed by a 6-second controlled exhale |
The participants completed the breathing intervention for five minutes immediately before the stress test and for another one minute during the test, after the presentation portion and before the cognitive challenge.
The study was registered as NCT06986135, with Texas State University listed as the sponsor. ClinicalTrials.gov describes the project as an investigation of breathing interventions and their effects on stress biomarkers and cognitive performance following a Trier Social Stress Test.
The researchers used a modified virtual version of the Trier Social Stress Test, a widely used laboratory method for inducing psychological stress.
Participants prepared a five-minute presentation arguing that they were strong candidates for a job. They then delivered the presentation virtually in front of a prerecorded panel of two neutral-looking judges. Afterward, they completed a Stroop color-word challenge and mental arithmetic.
It was deliberately uncomfortable.
The purpose was to create enough psychological pressure to produce measurable physiological changes.
What Box Breathing Actually Meant in the Study
“Box breathing” can refer to several slightly different breathing patterns in popular wellness content.
In this experiment, the protocol was precise: four seconds inhaling, four seconds holding, four seconds exhaling, and four seconds holding. The cycle was then repeated.
This is important because research results cannot automatically be applied to every breathing exercise marketed under the name box breathing.
The researchers provided participants with a visual timer indicating when to inhale, hold, and exhale. The intervention was intentionally brief, making it potentially relevant to situations where people cannot spend 20 or 30 minutes practicing.
The prolonged-exhalation group followed a different pattern.
Participants took a deep nasal inhalation for approximately three seconds, followed by a controlled six-second exhalation through pursed lips. This breath was performed approximately once every 30 seconds, with normal breathing between repetitions.
The comparison is valuable because it separates two commonly promoted approaches: equal-ratio breathing with breath holds versus breathing that emphasizes a longer exhalation.
The Stress Test Worked
Before looking at the breathing techniques, the researchers first needed to establish that the stress challenge actually produced a stress response.
It did.
The virtual Trier Social Stress Test significantly increased heart rate, state anxiety, salivary alpha-amylase, and secretory immunoglobulin A across the experiment.
That is important because a stress intervention cannot be evaluated properly if the experimental stressor fails to produce measurable stress.
The normal-breathing group showed the expected increases in several measures after the stress challenge.
This gave researchers a baseline against which they could compare the two breathing interventions.
The breathing groups did not eliminate the stress response altogether. Instead, several of their responses were smaller.
That distinction is central to interpreting the findings.
Both Techniques Reduced Heart-Rate Responses
Heart rate was one of the clearest physiological outcomes.
The normal-breathing group experienced an increase in heart rate following the stress challenge. The box-breathing and prolonged-exhalation groups showed attenuated responses. According to the researchers, both slow-breathing interventions reduced the post-stressor increase in heart rate compared with normal breathing.
This provides a straightforward physiological signal that the breathing interventions changed the body’s reaction to the stressor.
However, it does not establish why.
Several mechanisms could contribute. Slow breathing can influence respiratory-cardiac interactions and autonomic activity, while deliberately controlling respiration may also change how participants interpret and respond to a stressful situation.
The study was not designed to determine which mechanism was responsible.
Instead, its value lies in showing that a very short intervention was associated with a measurable difference in cardiovascular stress reactivity.
Anxiety Responses Also Changed
The researchers measured state anxiety using the State Anxiety Inventory.
The normal-breathing group showed a significant increase in anxiety from before to after the stress test. The two breathing groups did not demonstrate the same increase. Pairwise comparisons showed that the breathing interventions attenuated the post-stressor anxiety response relative to normal breathing.
This is important because the result connects the physiological findings with a subjective psychological measure.
Participants were not simply showing different heart-rate patterns while reporting identical experiences.
Their reported momentary anxiety also responded differently.
That does not prove that breathing exercises can treat an anxiety disorder. The experiment examined acute state anxiety in healthy adults during a laboratory stress challenge, not long-term anxiety symptoms or clinical diagnoses.
Still, the alignment between heart rate and state anxiety makes the findings more compelling than a study relying on only one measurement.
Salivary Alpha-Amylase Added Another Layer
The study also measured salivary alpha-amylase, or sAA, a biomarker commonly used in research involving sympathetic nervous-system activity and acute stress.
The normal-breathing group showed a post-stressor increase in sAA. Both box breathing and prolonged exhalation attenuated this increase.
This creates an interesting three-part pattern:
subjective anxiety changed, heart rate changed, and a salivary stress marker changed.
That is one reason the researchers describe their findings as evidence that brief breathing techniques can buffer several peripheral and subjective markers of acute stress.
It also illustrates why physiological research can be more informative than simply asking whether meditation or breathing “feels good.”
A participant’s perception matters, but the body provides additional information.
Not Every Stress Marker Responded
The most important limitation may be what didn’t change.
Cortisol did not show a significant stress response across the groups. The researchers suggest that the modified virtual stress test may have been too brief or interrupted to produce the sustained hypothalamic-pituitary-adrenal response normally associated with a strong cortisol increase.
This means the study cannot be interpreted as evidence that box breathing or prolonged exhalation reduces cortisol.
That would be an overstatement.
The same caution applies to heart-rate variability. Despite the physiological effects observed in heart rate and other measures, the researchers did not find significant differences in HRV across the breathing conditions.
This is particularly interesting because HRV is frequently used in popular wellness discussions as a supposed measure of nervous-system balance.
The study demonstrates why individual biomarkers should not be treated as universal indicators of stress regulation.
One physiological measure can change while another remains unchanged.
Cognitive Performance Did Not Improve
The researchers also wanted to know whether breathing techniques would preserve or improve performance during the stressful cognitive tasks.
The answer was more limited.
There were no significant treatment effects on cognitive performance. The only notable effect was a small overall change in Stroop response time, which the researchers interpreted as potentially reflecting practice or familiarization rather than a breathing-specific benefit.
This matters because breathing exercises are sometimes promoted as a way to immediately sharpen concentration under pressure.
The Texas State study does not provide strong evidence for that claim.
The interventions appeared more useful for certain measures of stress reactivity than for the participants’ actual performance on the cognitive challenges.
For people interested in mindful breathing, that distinction is worth keeping in mind: feeling less physiologically activated does not necessarily mean performing better on a demanding mental task.
Box Breathing Was Not Clearly Better Than Prolonged Exhalation
The study’s design also addresses a popular question: Which technique works better?
The answer is not obvious from these results.
Both box breathing and prolonged exhalation attenuated several stress responses compared with normal breathing. But the researchers did not establish a broad, statistically significant superiority of one technique over the other across the measured outcomes.
That means the article should not be interpreted as evidence that box breathing is universally better than prolonged exhalation—or vice versa.
Instead, the study supports a more general finding:
brief, structured slow-breathing interventions can influence several markers of acute stress.
The exact breathing pattern may matter in future research, but this experiment was not large enough to establish a definitive winner.
Why the Six-Minute Intervention Is Interesting
One of the study’s most practical characteristics is the intervention length.
Participants practiced their assigned technique for five minutes before the stress test and another minute during the test. That means the researchers were testing an intervention that could realistically fit into a short break, pre-performance routine, or high-pressure transition.
That could be relevant for occupations in which stress occurs suddenly.
The researchers specifically discuss high-stress professions such as law enforcement, firefighting, and military service, where people may need techniques that require little equipment and can be deployed quickly.
The study does not prove that the techniques improve performance in those professions.
The participants were healthy adults in a laboratory setting.
But the short protocol provides a rationale for conducting future research in operational environments where stress is more realistic and consequences are more significant.
Why the Virtual Stress Test Matters
The use of a virtual Trier Social Stress Test was practical but also introduces an important limitation.
Traditional versions of the TSST generally involve live evaluators. This experiment used prerecorded judges presented through a virtual setup. The researchers selected that approach partly because maintaining consistent live judging across sessions would have required additional personnel.
The virtual test still produced significant increases in several stress markers.
However, the absence of a cortisol response suggests that it may not have generated the same endocrine response as a longer, uninterrupted social-evaluative stressor.
That creates an important methodological question for future studies.
Would the same breathing techniques produce similar effects during a live interview, emergency simulation, public performance, or other real-world stressor?
The current research cannot answer that.
What the Study Says About the Body’s Stress Response
The most useful interpretation is that breathing appears capable of influencing some layers of acute stress physiology without necessarily changing all of them.
The researchers observed reductions or attenuation in heart rate, state anxiety, and salivary alpha-amylase responses. Secretory immunoglobulin A also increased across the full sample, but the change did not differ significantly between breathing conditions. Cortisol, HRV, and cognitive performance likewise did not show significant breathing-specific effects.
That pattern is scientifically more valuable than a simple positive result.
It shows that the stress response is not one switch that breathing either turns on or off.
Different biological systems respond on different timelines and through different mechanisms.
A short breathing exercise may affect cardiovascular and subjective stress responses while leaving endocrine measures unchanged.
This is consistent with the broader view that stress is a coordinated but complex interaction between the brain, autonomic nervous system, cardiovascular system, endocrine signaling, and behavior.
Could Box Breathing Be Useful in Everyday Life?
The study provides a reasonable scientific basis for viewing brief breathing as a potential acute stress-management tool, but it does not establish a universal prescription.
For someone experiencing ordinary situational stress, a structured breathing pattern may provide a short period of attentional control and physiological regulation.
The strongest evidence from this particular experiment is that participants using box breathing or prolonged exhalation experienced smaller changes in several markers after an acute laboratory stressor compared with participants who breathed normally.
That is promising.
But it is not the same as proving that six minutes of box breathing will lower chronic stress, prevent anxiety disorders, reduce blood pressure over months, or improve long-term health.
Those questions require different studies.
Repeated interventions would need to be tested over weeks or months, ideally with larger and more diverse populations and real-world stress measurements.
What Researchers Should Test Next
The next stage of research should move beyond a single laboratory session.
A larger study could compare box breathing and prolonged exhalation over several weeks and examine whether repeated practice produces changes in resting cardiovascular measures, stress reactivity, sleep, anxiety, and recovery.
Researchers could also recruit people who regularly experience high occupational stress rather than healthy university participants.
The distinction between acute stress reduction and long-term stress resilience deserves particular attention.
The current study shows that a brief intervention can alter several responses to a single stressor. It does not establish that participants became more resilient to future stress.
Another useful direction would be direct comparison with other strategies, such as mindfulness meditation, progressive muscle relaxation, or brief cognitive interventions.
That could help determine whether breathing has a unique physiological effect or whether its benefits are primarily associated with structured attention and a temporary interruption of the stress cycle.
The Evidence Supports a Narrower Claim—and That Makes It Stronger
The new Texas State University research does not prove that box breathing is a cure for stress.
It does something more useful.
It provides controlled evidence that two very brief breathing techniques—4:4:4:4 box breathing and prolonged exhalation—can attenuate several physiological and psychological responses to an acute laboratory stressor.
The experiment included 66 adults and measured multiple systems simultaneously. Both breathing interventions reduced post-stressor increases in heart rate, state anxiety, and salivary alpha-amylase compared with normal breathing. But there were no significant group differences in HRV, cortisol, or cognitive performance.
That mixed pattern is exactly why the study deserves attention.
Stress is not a single number, and breathing does not appear to affect every part of the response in the same way.
For people interested in breathwork, the practical message is therefore fairly simple: brief, structured breathing may be a useful way to influence the body’s response to acute stress, particularly when the goal is immediate regulation rather than treatment of a chronic condition.
For researchers, the bigger question is whether these short-term changes can eventually translate into better recovery, resilience, and health when the practice is repeated consistently.
That answer will require longer studies, larger samples, and more realistic stress environments.
For now, the evidence suggests that the breath is more than a passive response to stress. Under controlled conditions, changing the way a person breathes for only a few minutes can alter several measurable components of the body’s reaction to pressure—while also reminding us that no single breathing technique can be expected to change every part of the stress response.