Your Heaviest Rep Is Decided Before the Bar Moves
Every strength coach cues the brace. Big breath, tight trunk, drive. Very few coach the breath itself with the same precision they apply to bar path or foot position.
That is a gap. How an athlete breathes under a heavy load changes trunk pressure, blood pressure and how many quality reps they complete. It is a skill, and it can be trained.
Here is what the research shows about the Valsalva manoeuvre, where it helps, what it costs, and how we coach breathing in the weights room.
What the Valsalva Manoeuvre Actually Does
The Valsalva manoeuvre is a forced exhale against a closed airway. In the gym it looks like this: take a breath in, lock it in, brace hard and lift without letting air escape.
That effort raises pressure inside the abdomen and the chest. A stiffer, pressurised trunk is a more stable platform for transferring force from the legs and hips to the bar.
The pressure depends on the lift
Blazek and colleagues (2019) published a systematic review in Biology of Sport that pooled 16 studies measuring intra abdominal and intrathoracic pressure during high intensity resistance exercise.
Squats produced the highest intra abdominal pressure, above 200 mmHg. Deadlifts, rows and leg press sat in a range of roughly 161 to 176 mmHg. The bench press produced the lowest, at about 79 mmHg.
Intrathoracic pressure was highest in the leg press, deadlift and box lift, at around 105 to 130 mmHg. The authors concluded that body position and external load together determine how much pressure is generated.
Their practical advice was clear. Bench press and rows suit beginners and people with high blood pressure. Untrained lifters should hold off on heavy squats, deadlifts and cleans until they have adapted to high loads.
The Cost: Blood Pressure Under Load
The trunk pressure that helps you lift also loads the cardiovascular system. That is the trade off every S&C coach needs to understand.
MacDougall and colleagues (1985) measured blood pressure directly from the artery in five experienced bodybuilders during heavy lifts to failure, published in the Journal of Applied Physiology.
During the double leg press, average peak blood pressure reached 320/250 mmHg. One lifter exceeded 480/350 mmHg. Even a single arm curl to failure averaged 255/190 mmHg.
The researchers measured mouth pressures of 30 to 50 mmHg during the lifts, showing the Valsalva response was part of the rise. They concluded the extreme values came from three things combined: muscles squeezing the blood vessels, a strong pressor reflex, and the Valsalva itself.
Be clear about the limits. This was five trained men, decades ago, lifting to failure. It shows how high pressure can go. It does not show that heavy lifting is unsafe for healthy athletes, and it was not designed to.
What it does show is why the breath matters for anyone with a heart or blood pressure issue, and why long, maximal breath holds under load are not something to repeat carelessly.
Does Breathing Out Cost You Strength?
Coaches often worry that exhaling during a lift will leak pressure and cost performance. The evidence on breathing patterns during actual training sets is still thin.
Deniz and Erdemir (2025), in BMC Sports Science, Medicine and Rehabilitation, compared three strategies in 12 resistance trained men doing maximal bench press: breathing in during the lift, breathing out during the lift, and holding the breath.
The clearest finding was against inhaling during the effort. Breathing in on the lift produced fewer completed sets and less total training volume than the other strategies. Most blood pressure and heart rate variability measures did not differ between conditions.
The authors described their own results as preliminary, given the small sample and a single exercise. Treat this as an early signal, not a rule. It does support one simple point: do not breathe in while driving the bar.
How We Coach Breathing in the Weights Room
This is how Vincere Protocol applies the research with teams. The aim is not to ban the brace. It is to make breathing a deliberate, coachable part of every lift.
Match the breath to the load
Near maximal efforts: a short, deliberate brace for the hardest part of the rep, then release. Keep the hold as brief as the rep allows. No grinding through long sets on one breath.
Submaximal and volume work: breathe in during the lowering phase and out through the effort, keeping the trunk firm. That avoids inhaling on the drive, the pattern linked with fewer completed sets.
Athletes new to heavy loads: build trunk control on lower pressure lifts such as bench press and rows first, in line with the systematic review advice.
Control the breath between sets
Most athletes finish a heavy set and keep mouth breathing hard long after the effort is over. We coach the opposite: light, slow, deep nasal breathing with a long, relaxed exhale.
A 2022 meta analysis by Laborde and colleagues found that voluntary slow breathing increases heart rate variability measures linked to vagal activity. That study was not done in the weights room and did not test lifting performance, so we use it as a calm, repeatable reset, not a promise of faster recovery.
Keep the tools separate
The Valsalva is a breath hold at high lung volume with straining. Breath hold sprint training is a hold after a normal exhale, at low lung volume, used to build repeated sprint ability. They are different tools with different effects. Do not mix them in the same session or credit one with the results of the other.
Safety: never practise breath holds in or near water, never while driving, never alone, stop if dizzy, and get medical clearance first if pregnant or with heart, lung or blood pressure conditions.
FOR ELITE ATHLETES, THIS CAN HELP YOU
✔ Understand how bracing raises trunk pressure, and which lifts load it most
✔ Use a short, deliberate brace on near maximal reps instead of long, uncontrolled holds
✔ Avoid breathing in during the lift, the pattern linked with fewer completed sets in early research
✔ Respect the blood pressure cost of heavy lifting, especially with any cardiovascular history
✔ Settle your breathing between sets with light, slow nasal breathing
Performance takeawayThe brace is a tool, not a reflex.
Coach the breath like you coach the bar path.
Want this in your program? Enquire about Vincere Protocol for your team.
