Breathing exercises blunt the body’s physical reaction to acute stress

Short breathing exercises can prevent spikes in heart rate and anxiety when people face high-pressure situations. In a study published in Comprehensive Psychoneuroendocrinology, researchers found that just a few minutes of controlled breathing kept physiological stress markers from rising during an intimidating public speaking task. These routines offer a highly accessible way for individuals in high-stress occupations to manage their bodily responses in real time.

Acute psychological stress triggers a physiological reaction commonly known as the fight or flight response. Heart rate climbs, respiratory rate quickens, and metabolic activity shifts so the body prepares for immediate physical action. This reaction is generally an evolutionary advantage, allowing individuals to meet sudden environmental demands with heightened physical and cognitive energy. The nervous system coordinates these rapid changes to ensure survival in the face of an immediate threat.

However, modern stressors often provoke this bodily reaction even when physical action is not required. When a person remains in this heightened state, it can impair cognitive function and physical performance. Repeated activation of these bodily systems can also contribute to inflammation and increase the risk of heart disease. For people in professions that regularly deal with intense situations, like firefighters, military personnel, and police officers, managing this bodily reaction is a matter of occupational safety.

Identifying accessible, low-cost ways to moderate the nervous system is an active area of public health research. Researchers have tested various interventions to help individuals regulate their stress, including specialized exposure training and nutritional supplements like caffeine. While some of these approaches show modest benefits for cognitive focus, they often fail to lower the physical toll of stress. Short breathing exercises offer a highly practical alternative because they require no equipment and can be performed almost anywhere.

Lead author Matthew J. McAllister, a researcher at Texas State University, along with colleagues, wanted to test two ultra-short breathing interventions. Prior research suggests that pacing one’s breath at a slower rate can manipulate the autonomic nervous system to promote calmness. Many techniques exist, but it is not always obvious which methods work best during a brief window of time before a high-pressure event. First responders and military personnel often need a method that takes only a few minutes to apply.

To evaluate practical options, the team focused on box breathing and prolonged exhalation. Box breathing, sometimes called tactical breathing, is popular among law enforcement and military personnel. It involves inhaling, holding the breath, exhaling, and holding the breath again in equal four-second intervals. Prolonged exhalation, sometimes referred to as a reset breath, involves taking a deep breath and letting it out very slowly to mimic a physiological sigh.

The research team recruited sixty-six university students for the study. To ensure a clean baseline, the participants had to arrive at the laboratory with an empty stomach, fasting for at least four hours prior to the session. The researchers randomly divided the volunteers into three evenly matched groups: normal breathing, box breathing, and prolonged exhalation. Participants first rested in the laboratory for ten minutes before providing their baseline measurements.

These initial readings included a measure of their resting heart rate and a self-reported anxiety questionnaire. They also provided a saliva sample by passively drooling into a small vial. Saliva contains alpha-amylase, an enzyme that reliably spikes in response to nervous system activation, as well as proteins related to immune function. The researchers then informed the participants that they had to deliver a five-minute speech.

The volunteers were instructed to prepare a presentation convincing a panel of judges that they were the best candidate for a specific job. They were given just five minutes to take notes and organize their thoughts. Before starting the speech, participants spent five minutes practicing their assigned breathing routine. Researchers monitored the participants in real time with a respiration belt to verify they maintained the correct breathing rhythm.

The box breathing group followed a visual timer on a screen to match the four-second inhaling and exhaling intervals. The prolonged exhalation group took a three-second deep breath through the nose, followed by a six-second exhale through pursed lips. They did this specific breath once every thirty seconds, simply breathing normally in the intervals between the prompted deep breaths. The control group received no special instructions and simply breathed as they normally would.

Participants then delivered their speech over a video call to a pre-recorded video of two professionally dressed judges. The judges in the video maintained neutral facial expressions and appeared to be taking notes. The participants were told beforehand that the judges would not respond to questions or interact in any way. Immediately after the five-minute presentation ended, the participants performed one more minute of their assigned breathing technique.

Finally, the participants completed two rapid cognitive tests on a computer. The first was a color-word matching game where the name of a color appeared in a conflicting font color, requiring the user to quickly identify the text color. The second assessment involved a series of mental math problems, giving the participant just ten seconds to solve addition and subtraction equations. The researchers collected follow-up heart rate data, anxiety questionnaires, and saliva samples immediately after the tasks and again twenty-five minutes later.

The public speaking task successfully induced a physiological response in the control group. Participants who breathed normally experienced increases in their heart rate, self-reported anxiety, and salivary alpha-amylase levels. These increases demonstrated that the virtual speaking scenario effectively simulated a stressful social evaluation. In contrast, the participants who practiced either of the two controlled breathing techniques did not show these spikes.

Box breathing and prolonged exhalation both prevented the typical surge in anxiety and physiological stress markers. The researchers noted that preventing this physiological spike could be highly beneficial in real-world scenarios where rapid recovery is required. The study found no differences between the three groups regarding cognitive performance. Participants in all groups scored similarly on the mental math and color-word matching tests, suggesting the breathing exercises neither helped nor hindered their immediate cognitive speed.

The researchers also measured the stress hormone cortisol from the saliva samples, but levels actually declined across all groups. Cortisol typically follows a natural daily rhythm, dropping as the day goes on. The researchers suggest the modified speech task, which included breaks for breathing exercises, might not have been continuous enough to trigger a true cortisol response. A standard version of this psychological stress test usually involves ten solid minutes of uninterrupted social evaluation to activate the body’s hormone production.

Using a pre-recorded video of judges instead of a live panel introduces a limitation to the experimental design. If participants realized the judges were a recording, they might have felt less threatened by the evaluation. The researchers did not formally ask the participants if they noticed the deception after the experiment concluded. However, the task still elevated stress markers in the control group, suggesting it functioned adequately as a mild stressor.

The study also relied on resting measurements for heart rate variability, which tracks the tiny time differences between heartbeats. The team took these readings before and after the tasks rather than during the actual breathing exercises. This timing prevents researchers from seeing exactly how the breathing routines acutely alter nervous system activity in the exact moment of practice. The baseline measurements for heart rate variability were also relatively high across all groups, which is typical for a young, healthy sample.

This high baseline might limit the ability of the measurements to detect subtle stress-related changes. Additionally, the sample size restricted the researchers’ ability to analyze differences in how males and females might respond to the interventions. Prior research shows that men and women often exhibit different hormonal responses to psychological stress. Future research could explore how different demographic groups benefit from various breathing patterns during longer evaluations.

The study, “Box breathing and prolonged exhalation reduces markers of physiological stress reactivity in response to a virtual Trier Social Stress Test,” was authored by Matthew J. McAllister, M. Hunter Martaindale, Nate Sutton, and Judith P. Andersen. The researchers conducted their work at Texas State University and the University of Toronto Mississauga.