5 Scientific Reasons Breath Holding Enhances Performance and Builds Resilience
Breath holding, also known as voluntary apnoea, the practice of intentionally holding the breath after inhalation or exhalation, is gaining attention well beyond the freediving world. Emerging research and applied training demonstrate that strategic breath-hold practices can significantly enhance sports performance and foster greater physical and mental resilience.
After guiding thousands of people through breathing workshops and trainings, and working with On's top sponsored global athletes, we have witnessed the profound impact of this practice firsthand. Breath holding is not only a powerful tool for building physical resilience and improving performance, but also a possible pathway to deeper self-awareness. It enhances the communication between mind and body, helping individuals shift out of overthinking and reconnect with their inner state.
By intentionally holding the breath, we offer the nervous system a reset, very often allowing people to emerge from the practice feeling calmer, more grounded, and mentally clearer, while also supporting faster recovery and a renewed sense of vitality and energy.
The practice of breath holding offers a range of potential benefits, including improved physiological function, enhanced stress adaptation, and greater overall resilience across a wide range of individuals, including both professional and recreational athletes. And it's accessible to anyone — yet few practices offer so much in return.
It is important to note that there are various breath-holding techniques, and selecting the appropriate method depends on factors such as the desired outcome, individual health status, and CO₂ tolerance. As a general recommendation for initial practice, we advise starting with breath-holding techniques that do not involve controlled hyperventilation. It is important to build the practice gradually, allowing the body and nervous system to adapt safely over time.
What Happens in the Body
When you intentionally hold your breath, several physiological shifts unfold at once. CO₂ begins to rise. Oxygen saturation falls gradually. The spleen contracts. The autonomic nervous system moves through a sympathetic activation followed by a parasympathetic rebound. The diaphragm — your largest involuntary muscle — meets a load it can adapt to. Done with intention and care, this short, controlled stress becomes a training stimulus, much like cold exposure or a heavy lift. The body learns. The mind learns. And very often we observe people gaining more access to their emotions, finding ways to use them as fuel rather than suppressing them, creating a space to feel.
The five sections that follow break down the most relevant of these adaptations, anchored in current peer-reviewed research.
1. Boosted Red Blood Cell Availability
Breath holding initiates a two-phase adaptation to enhance red blood cell availability and oxygen transport:
First, spleen contraction occurs as a response to apnoea-induced hypoxia, mediated by sympathetic nervous system activation. The spleen releases a reserve of red blood cells into circulation, leading to a temporary increase in haemoglobin concentration and improved oxygen-carrying capacity (Bakovic et al., 2003; Bouten et al., 2024). The response is graded — the deeper the drop in oxygen saturation, the stronger the contraction, with rising CO₂ and the cessation of breathing itself contributing as additional stimuli (Lodin-Sundström & Schagatay, 2010). For elite freedivers, baseline spleen volume is also higher than in the general population, suggesting a long-term structural adaptation to regular practice (Schagatay et al., 2012).
Second, repeated and sufficiently intense breath-hold exposure can stimulate the release of erythropoietin (EPO), a hormone produced by the kidneys in response to low oxygen levels. EPO acts on the bone marrow, promoting the production and release of new red blood cells. This longer-term adaptation may improve aerobic performance by increasing the blood's overall oxygen-carrying capacity. However, current evidence suggests that a significant EPO response requires a sufficiently high hypoxic dose and is more consistently observed in experienced breath-hold practitioners (de Bruijn et al., 2008; Bouten et al., 2024).
2. Improved Anaerobic Performance and Lactate Tolerance
Breath-hold training has been shown to enhance the body's ability to perform under anaerobic conditions, meaning when oxygen demand exceeds supply. A 2022 systematic review and meta-analysis published in Frontiers in Physiology found that apnoea training significantly increased peak blood lactate concentration compared to normal breathing, indicating an improved capacity to sustain high-intensity efforts before fatigue sets in (Fernández et al., 2022).
This adaptation is particularly relevant for athletes engaged in repeated sprint efforts, interval training, or sports requiring sustained explosive output. More recent work on repeated-sprint training combined with voluntary hypoventilation has shown moderate but meaningful improvements in sprint-fatigue resistance among trained athletes, with a stronger glycolytic stimulus than conventional training alone (Trincat et al., 2017). Notably, these same studies generally show no significant change in VO₂max, suggesting that breath-hold training is best understood as a complement to aerobic training rather than a replacement for it.
3. Building CO₂ Tolerance
The urge to breathe is primarily driven by rising CO₂ levels in the blood, not by falling oxygen levels. Breath holding gradually builds the body's tolerance to higher concentrations of CO₂, leading to improved control over the respiratory drive, better acid-base balance, and greater resilience under both physical and psychological stress. Over time, this practice serves as a physiological training method to slow down breathing patterns naturally, supporting more efficient and calmer respiration at rest and during effort.
Trained breath-holders show a measurably blunted ventilatory response to hypercapnia, meaning they remain composed at CO₂ levels that would prompt panic-breathing in untrained individuals (Delapille et al., 2001; Roecker et al., 2014). Building CO₂ tolerance is valuable not only for athletic and endurance performance but also for enhancing stress management, emotional regulation, and overall resilience in daily life, in part because the same chemoreceptor pathways that drive air hunger are deeply connected to the brain's threat and arousal systems (Fincham et al., 2023; McKeown, 2021; Bouten et al., 2024).
4. Increasing Diaphragm Strength and Respiratory Efficiency
Breath-hold training serves as a unique form of isometric exercise for the diaphragm and accessory respiratory muscles. Over time, this practice can lead to improved respiratory efficiency, stronger inspiratory and expiratory muscles, and enhanced breath control during both exercise and recovery phases.
Research has shown that breath-hold training can significantly improve respiratory muscle strength, measured as maximal inspiratory and expiratory pressure, and breath economy, particularly in competitive athletes (Cross et al., 2013; Carvajal-Tello et al., 2024). It's worth noting that while breathing muscles become demonstrably stronger, changes in static lung volumes (such as forced vital capacity) tend to be more modest in already-trained adults, the primary benefit lies in how efficiently and powerfully the existing capacity is used. As the diaphragm strengthens and becomes more available, athletes often describe a felt sense of "more room" in their breathing, with knock-on effects for posture, ribcage mobility, and overall ease under load.
5. A Calmer, More Focused, and Resilient Mind
Beyond physical adaptations, breath holding has profound effects on the nervous system. It often activates the parasympathetic nervous system after an initial sympathetic spike, leading to increased heart rate variability (HRV), improved emotional regulation, and sharper mental clarity (Andersson et al., 2004; Bouten et al., 2024).
This biphasic autonomic response, moving deliberately into stress and back out again, is itself a form of resilience training. Resilience is not the absence of stress but the body's capacity to enter a stress state, hold it without panic, and return to baseline cleanly. Breath holding rehearses precisely this arc, and trained practitioners show greater HRV shifts and faster autonomic recovery over time.
Practitioners often report feeling more centered, clear-headed, and present after breath-hold sessions — effects that extend into training, competition, and daily life. By improving emotional regulation and nervous system balance, breath holding also contributes to building greater psychological resilience, helping individuals remain composed and focused under pressure. A 2023 meta-analysis of randomised controlled trials found that breathwork practices, including those that incorporate breath retention, were associated with meaningful reductions in self-reported stress and improvements in mood (Fincham et al., 2023).
A Note on Safety
Because breath holding is a form of physiological stress, two safety principles deserve emphasis. Never combine breath-holding with water — shallow-water blackout can be fatal and disproportionately affects fit, healthy individuals. And avoid hyperventilation before a breath-hold without the supervision of a qualified breathwork instructor, as it suppresses the natural CO₂ trigger to breathe and allows oxygen to fall to dangerous levels with no warning. Those who are pregnant, have uncontrolled cardiovascular disease, a history of seizures, or severe respiratory conditions should consult a qualified professional before practising. Always practise dry, seated or supine, and build gradually.
Conclusion
Breath-hold training, once mainly associated with freediving, is now emerging as a powerful tool for enhancing physical performance, accelerating recovery, and building greater resilience — both mentally and physically. Research shows how strategic breath holds improve oxygen transport, sharpen anaerobic capacity, build CO₂ tolerance, strengthen the respiratory system, and deepen the mind-body connection.
Yet beyond the science, what we witness time and time again in our keur breathwork teacher trainings and workshops is something deeper: a shift. Participants leave not only breathing differently but living differently, with a calmer presence, more clarity under pressure, and a renewed sense of inner strength.
In a world that often pulls us outward, breath-hold training invites us back into ourselves — steady, focused, and alive. If you're curious to learn more, we've just launched our new Sports Performance + Resilience Workshop, designed for professional and recreational athletes, sports teams, and anyone ready to explore deeper.