Respect the Stimulus
Breath hold training works because it creates real stress. Oxygen levels fall, CO2 rises, and the body has to cope.
Used well, it is one of the most effective repeated sprint tools in the research. Used carelessly, particularly anywhere near water, it can be lethal.
That is exactly why it has to be done properly. Coaches and team doctors are right to ask about safety first, so here is a straight answer.
Land Versus Water
Two Very Different Activities
The phrase breath hold training covers two activities that carry very different risks.
Breath hold sprint training on land. This is what the performance research has tested. Athletes breathe out normally, hold at low lung volume for a short sprint, then breathe freely during the recovery. Each hold lasts seconds, on solid ground, under supervision.
Long breath holds in water. Underwater swimming challenges, static holds in a pool, freediving without training and supervision. This is where people die.
Vincere Protocol teaches the first. We never teach, recommend or condone the second.
Mixing the two up is the most dangerous mistake an athlete can make. A drill that is controlled on a training field becomes a drowning risk the moment it moves into a pool, because there is no safe place to lose consciousness underwater.
Shallow Water Blackout: The Absolute Rule
Pearn, Franklin and Peden (2015) describe hypoxic blackout as a distinct and preventable cause of drowning. Victims are often young, fit and usually male.
The mechanism is simple and brutal. Overbreathing before going under drives CO2 down. CO2 is the body's main signal to breathe, so the urge is delayed while oxygen keeps falling. The swimmer can lose consciousness underwater with no warning.
Deaths have occurred in pools and in the sea, including among people training for underwater hockey, synchronised swimming and freediving, and in submersion endurance challenges. The authors identify awareness of the risk as the key to prevention.
So the rule is absolute: no breath hold training in or near water. Ever. That includes pool recovery sessions, ice baths and swimming squads. For swimmers, all breath hold work stays on land.
And no one should ever hyperventilate before a breath hold, in or out of the water.
What the Studies Report
What Happens in the Body During Breath Hold Sprints
The studies measured the stimulus, and it is real.
In highly trained rugby players, Fornasier Santos et al. (2018) recorded a mean oxygen saturation of 90.1% across breath hold sprint sessions, compared with 95.5% when sprinting with normal breathing.
In trained female soccer players, Ait Ali Braham et al. (2024) recorded 92.1% at the end of breath hold sprints at low lung volume, against about 97% with normal breathing or holds at high lung volume.
Woorons et al. (2019) looked at the brain. In 10 highly trained jiu jitsu fighters doing repeated shuttle sprints, oxygenation in the front of the brain fell more with breath holds than with normal breathing, a mean drop of 6.1 versus 1.5 on near infrared spectroscopy. Sprint times were not impaired, which the authors attributed to higher oxygen uptake during recovery.
That is the point of the method. A controlled drop in oxygen during short sprints is the training stimulus. It is also why the method needs structure, supervision and screening.
What the Research Tells Us About Tolerability
The published programs were completed by trained athletes across rugby, soccer, basketball, ice hockey, judo, cycling, swimming and triathlon.
The 2025 meta analysis by Précart et al. pooled 10 studies with 199 trained athletes. The main finding was better fatigue resistance in repeated sprints, with no effect on best sprint time.
Here is the honest limit. These trials were small, they included only healthy, trained participants, and they were designed to measure performance. They were not built to detect rare adverse events, so they cannot prove the method is risk free for everyone.
It is also worth remembering that a hold during a 6 second sprint is a very different dose from a long static hold. The sprint studies used short holds with free breathing in every recovery, which is a large part of why the stimulus stays controlled.
No published trial we rely on studied children, pregnant women or people with medical conditions. That is why screening is not optional.
Who Needs Medical Clearance
Get clearance from a doctor before starting breath hold training if any of the following apply:
Pregnancy.
Any heart condition, including known rhythm problems or a history of unexplained fainting.
Any lung condition, including asthma that is not well controlled.
High or low blood pressure, or blood pressure medication.
Any other condition where a drop in oxygen could be a concern, or if you are unsure.
Team doctors should own this screening, not the breathing coach. Build it into the preseason medical so every athlete is cleared before the first session.
For junior athletes, the published research in trained adults does not transfer automatically. Keep breath hold sprint work for adults unless a medical professional advises otherwise.
The Rules We Coach
Land only. Never in or near water.
Never alone. Always supervised by a coach who knows the method.
Never while driving or operating anything where a lapse matters.
No overbreathing. A normal exhale, then the hold. No power breathing beforehand.
Stop if dizzy. Lightheadedness, tingling, vision changes or confusion means the session ends.
Progress gradually. Start with short holds over a few strides before moving to full sprints.
Breathe freely in recovery. Every recovery between sprints is normal breathing. Never chain holds back to back.
Report symptoms. Athletes should feel free to tell staff about any unusual symptom, and staff should log it.
FOR ELITE ATHLETES, THIS CAN HELP YOU
✔ Train repeated sprint ability with a method tested in healthy trained athletes
✔ Understand the real oxygen drop involved, so the stimulus is respected
✔ Know the screening steps before starting
✔ Avoid the overbreathing and water risks linked to hypoxic blackout
Performance takeawayOn land, supervised and screened, breath hold sprint training is a controlled stimulus. In water, it can kill.
Control your breath. Control the result.
Want this in your program? Enquire about Vincere Protocol for your team.
