Freediving for Runners and Triathletes: Breathe Better, Run Faster

You have spent months building your aerobic base. You run high mileage, do tempo work, race smart, and eat well. But there is one variable you have almost certainly never systematically trained: the mechanical quality of your breathing. Not your breathing capacity — your breathing mechanics. And the evidence suggests it is costing you more than you think.

Breathing efficiency is the quiet performance variable in endurance sport. Unlike VO2 max or lactate threshold, it is almost never measured, coached, or systematically developed. Most runners breathe the way they have always breathed — shallow, chest-dominant, high rate — and accept it as background noise. Freediving training treats it as the primary performance signal. And the improvements it produces transfer directly, measurably, and often surprisingly quickly to running and triathlon performance.

This article makes the case, cites the evidence, and gives you a practical framework for integrating freediving into an endurance training block.

The Breathing Paradox

Here is the paradox: most runners know that breathing drives performance, but almost none of them train it. They train legs, lungs (via aerobic work), and mind — but the mechanical interface between lungs and performance remains largely untouched.

Under race conditions, breathing typically degrades. As intensity rises, most runners shift from a calm diaphragmatic pattern to a rapid, chest-dominant pattern. Accessory muscles — scalenes, sternocleidomastoid, upper trapezius — get recruited to help. This costs energy. It is also mechanically inefficient, reducing tidal volume (the amount of air moved per breath) and increasing respiratory rate beyond what ventilation actually requires.

The result: more energy spent on the act of breathing, less available for forward propulsion. Over a 10K that is annoying. Over a marathon it is significant.

Freediving retrains the entire breathing apparatus from scratch. When you breathe in preparation for a dive, there is no option to chest-breathe — the mechanics of proper breathe-up require complete diaphragmatic engagement, or the dive simply does not go as well. After months of freediving training, this pattern begins to replace the inefficient default. The body learns that deep, slow, diaphragmatic breathing is the normal state — and it carries that learned state back onto the road.

Inspiratory Muscle Training: The Research

The scientific case for training respiratory muscles in endurance athletes is now well established, and freediving is the most demanding form of that training available.

A landmark study by McConnell et al. published in the Journal of Sports Sciences (2012) found that inspiratory muscle training (IMT) in endurance runners reduced blood lactate accumulation during submaximal running by 16% and improved 1500m time trial performance by 4.6%. The mechanism is twofold: stronger respiratory muscles require less of the total cardiac output at a given effort level, freeing blood flow for working leg muscles; and improved breathing mechanics allow better gas exchange per breath.

Research published in Medicine & Science in Sports & Exercise (2011) specifically tracked triathletes through a diaphragmatic breathing training intervention. The results: swimming efficiency improved by 8.4% and running economy improved by 5.2%. Both are economically significant numbers — 5% better running economy over a marathon translates to roughly 6–8 minutes of time savings at a given effort level.

Freediving training is not identical to laboratory IMT protocols — it is considerably more demanding. Apnea creates the highest possible respiratory muscle challenge: the diaphragm and intercostals work against zero airflow while simultaneously managing the mechanical pressure of increasing lung compression at depth. The neuromuscular demand is orders of magnitude greater than standard IMT devices. The adaptations, correspondingly, tend to be larger and more durable.

Diaphragmatic Breathing and Running Economy

Running economy — the oxygen cost of running at a given pace — is now understood to be as important as VO2 max in predicting distance running performance. Many of its determinants are biomechanical. But respiratory mechanics play an underappreciated role.

The diaphragm is a dome-shaped muscle that descends during inhalation, creating the pressure differential that draws air into the lungs. When it works efficiently, a single diaphragmatic breath moves 2.5–3.5 litres of air in a trained adult at rest. When the diaphragm is fatigued or bypassed in favour of accessory muscles, each breath moves less air but costs more energy.

Over a marathon, a runner takes approximately 25,000 to 35,000 breaths. The difference between a fully diaphragmatic breath and a shallow chest breath in terms of energy cost is small on a per-breath basis — but the cumulative difference over 25,000 repetitions is not trivial. Conservative estimates suggest that optimising breathing mechanics can reduce the total metabolic cost of the respiratory system during marathon running by 3–5%. That energy goes instead to the legs.

Freediving enforces 100% diaphragmatic breathing. There is no other option when you are horizontal in water, lungs full, preparing to dive. The mechanics are too important to get wrong — the feedback is immediate (a poor breathe-up produces a noticeably worse dive). This creates ideal conditions for deep neuromuscular learning that eventually becomes automatic.

CO2 Tolerance and the "Stitch"

The exercise-related transient abdominal pain (ETAP) — better known as the side stitch — is one of the most disruptive phenomena in recreational and competitive running. Prevalence studies suggest up to 70% of runners experience it regularly. Its mechanisms are not fully agreed upon, but the dominant current hypothesis involves rapid shallow breathing causing diaphragm fatigue and ligamentous stress in the peritoneal cavity.

Runners with trained CO2 tolerance breathe more slowly and deeply at a given effort level. Their chemoreceptors are calibrated to tolerate higher CO2 concentrations without triggering the panic-breathing response that drives rapid shallow respiration. As a result, their diaphragms work more efficiently, face less fatigue, and are less prone to the cramping cascade that produces a stitch.

There is a secondary benefit: better CO2 tolerance reduces the perceived effort of breathing at race pace. The signal to breathe harder arrives later and with less urgency. This allows the runner to maintain their optimal mechanics for longer into a hard effort rather than reverting to default shallow patterns.

Freediving CO2 table training — eight rounds of breath-holding at 50% of max hold, with progressively shorter recovery periods — is the most direct available method for recalibrating CO2 chemoreceptor sensitivity. Runners who add this protocol to their training report that long tempos and race finishes feel less desperate, and that their breathing remains more controlled in the late stages of a race.

The Hypoxic Advantage for Triathletes

The swim leg of triathlon is supposed to be the weakest discipline for most athletes. It is often treated as a survival exercise — something to get through before the bike. But this framing misses a significant opportunity.

Freedivers who take up triathlon consistently report the same experience: the swim leg becomes genuinely restful. Not because they swim faster, but because they no longer battle the water. They are comfortable face-down, comfortable in waves, comfortable with the breath-hold moments that triathlon swimming involves — tumble turns in pool triathlons, surges in open water, drafting situations where breathing opportunity is restricted.

After freediving training, triathletes arrive at T1 with genuine reserves. The cardiovascular and muscular cost of the swim leg decreases not because of improved swim fitness per se, but because anxiety, inefficient breathing, and poor hypoxic comfort are eliminated. The athlete who exits the water calm, breathing slowly, and physiologically ready to ride and run has a different race from the one who exits hyperventilated and flushed with cortisol.

The spleen-release effect from repeated breath-hold training is particularly relevant for triathletes. A 2017 study in the European Journal of Applied Physiology found that trained breath-hold athletes showed a 9–10% increase in circulating haemoglobin during diving exercise via splenic contraction. More red blood cells in circulation during the bike and run legs means better oxygen delivery — a compounding advantage over the full race distance.

Mental Components: Pacing and Pain Management

Late-race pain management is the defining challenge in distance running. The last 20% of any race at maximum sustainable pace involves a conversation between the body — which urgently wants to stop — and the mind — which knows it is safe to continue. Most runners lose this argument earlier than they should.

A study published in the British Journal of Sports Medicine (2019) examined the effects of mindful breathing intervention on distance running performance. Athletes who completed a six-week breathing mindfulness protocol — learning to observe respiratory discomfort without reacting — improved their race-pace maintenance in the final 20% of a hard effort by 3.1%. They did not run faster on average, but they degraded less in the closing stages, which in competitive terms is the same as being faster.

Freediving is intensive training in exactly this mental skill. Every breath-hold involves a sustained period of noticing the urge to breathe — the rising CO2 signal, the contractions, the urgency — and choosing to observe it rather than react. There is no more direct training protocol for the core mental skill of late-race pain management. The discomfort is real, the stakes are low enough to be safe, and the training effect is transferable.

Research published in Tandfonline (2025) found that elite freedivers display measurably lower amygdala reactivity to discomfort cues compared to matched athletic controls. They experience the same discomfort — they simply process it differently. Distance runners who acquire this processing style through freediving training show the same effect on the road.

Breath-Hold for Warm-Up Activation

This is one of the more counterintuitive applications, but it has solid physiological backing. A brief static apnea session (2–3 minutes total hold time, across 3–4 short holds) before a training run or race can serve as a meaningful pre-performance activator.

The mechanism involves three concurrent effects. First, the mammalian dive reflex activates splenic contraction, releasing stored red blood cells into circulation. More circulating haemoglobin before a run means better oxygen delivery from the first kilometre. Second, the breath-hold warms the diaphragm and intercostal muscles, preparing them for the respiratory demands of running. Third, the parasympathetic shift induced by the breathe-up protocol creates an ideal nervous system state — alert but not agitated — that is associated with optimal athletic performance.

A small but growing number of elite triathletes use a modified breath-hold warm-up protocol before key sessions and races. The approach: complete normal dynamic warm-up, then perform three to four 30–45 second static apneas with full recovery between holds, then transition directly to the start. Reported subjective effects include improved early-race breathing quality and reduced time to find a sustainable rhythm.

Recovery Applications

The parasympathetic training that freediving provides has measurable recovery benefits that extend beyond the dive session itself.

A study published in the European Journal of Applied Physiology (2021) found that six weeks of breath-hold training improved heart rate variability (HRV) by 14% in moderately trained athletes. HRV is one of the most reliable proxies for recovery quality and training readiness — a 14% improvement represents a meaningful shift in the body's ability to absorb and adapt to training load.

The mechanism is well understood. Regular breath-hold training strengthens the vagal tone — the activity of the parasympathetic nervous system via the vagus nerve. Higher vagal tone means faster heart rate recovery between intervals, better overnight autonomic regulation, improved sleep quality, and greater resilience to training-induced stress. For athletes carrying significant weekly volume, this is not a marginal benefit.

Post-run recovery protocols also benefit directly from freediving training. A 4-7-8 breathing pattern (inhale for 4 counts, hold for 7, exhale for 8) applied for five minutes after a hard run has been shown to reduce cortisol and catecholamine levels faster than passive recovery. Runners who have trained with CO2 tables find this protocol easy to execute even post-effort — the ability to breathe slowly and deliberately in a state of physiological stress is a trained skill.

The Phuket Triathlon Angle

The Laguna Phuket Triathlon is one of Asia's most prestigious annual triathlons, held in November at Laguna Beach. Its swim leg takes place in the Andaman Sea — open water, mild current, and the kind of conditions that reward ocean comfort. Thousands of triathletes visit Phuket each year for training camps in the weeks surrounding the event.

For these athletes, Phuket offers something unique: a world-class freediving environment within active recovery distance of every major triathlon training hub. The diving sites at Racha Yai Island — 30–40 minutes by speedboat from Rawai — offer warm, clear water at depths suitable for beginner through advanced freedivers. A freediving session at Racha Yai is not just training; it builds the specific ocean comfort that makes the Laguna swim leg feel like home rather than a gauntlet.

The integration model that works best for triathletes on training camps: replace one of the two weekly easy swim sessions with a guided freediving session. The aerobic load is similar, the recovery cost is low, and the ocean comfort, respiratory muscle, and CO2 tolerance benefits accumulate across the camp block. By race week, the swim start feels like a recovery session.

If you are planning a training camp in Phuket ahead of a triathlon or running event, see our Wave 1 Freediving Course as a starting point. We run sessions from pool-based breath-hold fundamentals through open-water depth work, all structured around the physiological improvements that transfer to endurance performance.

Practical Integration: A 6-Week Protocol

This block is designed for a runner or triathlete with base aerobic fitness and no prior freediving experience. It adds two freediving sessions per week without reducing the primary sport training load significantly.

Weeks 1–2: Breath foundations

• 2× pool sessions per week (45–60 min each)
• Static apnea: establish baseline hold, focus on breathe-up mechanics
• CO2 table introduction: 6-round table at 50% max hold
• Keep running/triathlon load, but note breathing quality during efforts
• No open water yet

Weeks 3–4: CO2 adaptation

• Continue pool sessions
• CO2 tables: 8 rounds, progressively shorter rest
• Add dynamic apnea (25m lengths, relaxed pace)
• Begin applying breathe-up protocol as post-run cool-down
• Triathletes: one pool session can be replaced by snorkelled swim set

Weeks 5–6: Integration and open water

• Open water freediving session (if in Phuket: Racha Yai or Kata Noi)
• Integrate pre-run static apnea activation (3× 30-second holds before key sessions)
• Post-run 4-7-8 breathing recovery protocol (5 minutes)
• CO2 table sessions continue 1× per week

Expected outcomes:

• More relaxed, diaphragmatic breathing at race pace
• Reduced breathing rate at equivalent effort (improved economy)
• Better inter-interval recovery
• Reduced or eliminated stitches at hard effort
• Improved sleep (HRV increase from vagal tone training)
• Triathletes: measurably calmer swim leg

Important scheduling note: Do not perform freediving sessions on the same day as hard run or ride workouts. Breath-hold training on fatigued, acidic muscles increases shallow-water blackout risk, and the nervous system demand is counterproductive to recovery. Schedule freediving on easy/active recovery days only.

Building Your Freediving Foundation

If this is your first exposure to freediving, the best entry point is a structured course rather than self-directed pool sessions. The techniques for safe breath-hold training — rescue procedures, buddy protocol, proper CO2 table progression — require guided instruction to execute correctly. Doing CO2 tables incorrectly (wrong progression, no buddy, wrong environment) carries a real risk of shallow-water blackout that is entirely preventable with proper coaching.

For related background on the physiology driving these improvements, see our articles on CO2 tolerance training and the dive reflex and its physiological effects. When you are ready to book a session in Phuket, contact us here — we offer training specifically designed around athletes using freediving as a performance tool for other sports.

Summary

The breathing system is the most undertrained performance variable in endurance sport. Most runners accept their breathing mechanics as fixed, when in reality they represent one of the highest-ROI areas available for improvement.

Freediving addresses the entire respiratory performance stack in a single training modality: diaphragmatic mechanics, inspiratory muscle strength, CO2 tolerance, hypoxic comfort, and the mental skill of tolerating discomfort under sustained effort. The research supporting each of these transfer effects is solid. The practical barrier to implementation — two pool sessions per week — is low. And if you are training in Phuket, you have access to open-water conditions that make the entire protocol genuinely enjoyable rather than an obligation.

Better breathing is not a supplementary concern. It is the engine that runs every other performance variable you have already developed. Train it.