Squats and deadlifts load the spine with heavy axial loads. When you lift a 140 kg barbell on your back, this weight is transferred straight through the spine to the pelvis and legs. The spine by itself is an articulated column of bones and discs. Without muscular support and internal pressure, it would buckle under a load of just 20 kg. The Valsalva maneuver is the mechanism that turns the soft tissue of the torso into a rigid support cylinder.

This technique involves taking a deep breath, closing the airway, and actively bracing the core muscles before beginning the repetition. This is not simply holding your breath. It is a process of generating high internal pressure that protects the intervertebral discs and ensures optimal power transfer from the lower body to the barbell. We explain the mechanics, application, and safety limits of this technique below.

Mechanics of intra-abdominal pressure and core stability

Intra-abdominal pressure (IAP) is the hydrostatic pressure that builds up inside the abdominal cavity. This cavity is defined by specific anatomical boundaries: the diaphragm at the top, the pelvic floor at the base, the transversus abdominis and oblique muscles at the sides, and the multifidus muscles along with the thoracolumbar fascia at the back. When these tissues contract simultaneously around a fixed volume of air, space is restricted and internal pressure rises.

To understand the mechanism, think of an unopened soda can filled with liquid and carbonation. If you step on it, it supports the weight of an adult without deforming. But if you open the tab and empty the contents, the thin aluminum crumples immediately under minimal pressure. The body works the same way. The air trapped in the lungs and the tightening of the abdominal walls create a rigid structural pillar in front of the lumbar spine. This pressure chamber relieves the L4 and L5 vertebrae of a large portion of shear forces.

The difference in pressure values between normal breathing and a proper Valsalva during maximal effort is measurable in a laboratory setting. The measurements below show the change in loads:

The increase in intra-abdominal pressure reduces the need for the lower back muscles (such as the active vitality spinae) to produce all the extension torque on their own. This means these muscles fatigue less quickly and the spine remains in its neutral anatomical position throughout the lift.

Closing the glottis during bracing

The glottis is the anatomical opening between the vocal cords in the larynx. When you swallow or prepare to lift a heavy load, the glottis closes tightly. This closure seals the trachea and prevents air from escaping the lungs, regardless of how forcefully the expiratory muscles of the chest and abdomen contract.

There is a fundamental difference between simply holding your breath with your mouth closed and using the active Valsalva technique. If you merely close your lips, air moves into the oral cavity, puffs out the cheeks, and creates unwanted pressure in the blood vessels of the head. In a proper Valsalva, the seal happens deep in the throat, at the glottis. The mouth can remain slightly open, but air cannot pass upward or downward.

Once the glottis locks, bracing is engaged. You do not suck your stomach inward. Instead, you push your abdominal walls outward and to the sides, as if preparing to take a punch to the stomach. The diaphragm pushes down on the viscera, the glottis keeps the rib cage stable, and the abdominal muscles compress the entire system from the outside. This locking mechanism allows the body to act as a single, solid unit.

Adjusting the weightlifting belt in relation to breathing

A weightlifting belt does not passively support the lower back like a medical brace. Its role is to serve as a rigid external wall for the abdominal muscles to push against. Without a belt, the abdominal walls can expand slightly as intra-abdominal pressure rises. With a belt, this expansion is restricted. The result is that the same amount of muscular contraction and air produces roughly 28% to 42% higher intra-abdominal pressure compared to lifting without a belt.

To use the belt properly in combination with the Valsalva maneuver, its fit must follow specific criteria:

• Clearance check: The belt should not be so tight that it prevents a full inhalation. You should be able to slide your palm between the belt and your abdomen before taking in air. If you need to forcefully suck in your stomach to fasten the belt, it is too tight.
• Height placement: For squats, most lifters wear the belt just above the iliac crests, covering the navel. For deadlifts, many prefer wearing it 2 to 4 cm higher, so it does not restrict hip flexion in the starting position.
• Breathing direction: Do not breathe by lifting your chest and shoulders. Air must be directed low into the abdomen and ribs. The goal is to brace against the belt 360 degrees: in the front, at the sides, and in the back above the lower back.

If the belt is too tight, the volume of air you can inhale is drastically reduced. A smaller air volume means lower force production from the diaphragm, which negates the advantage of the belt.

Timing the exhalation at the completion of the repetition

The timing of the air release determines whether you maintain stability at the critical point of the lift. The most common error is premature exhalation. If you let the air out the moment the bar starts moving, intra-abdominal pressure drops instantly, the torso loses its rigidity, and the spine is exposed to dangerous flexion forces.

Application to the Squat

In the squat, the process follows specific movement phases:

1. In the standing position, take a deep diaphragmatic breath (to about 80% to 85% of your maximum capacity) and close the glottis.
2. Begin the descent while holding your breath and maintaining consistent pressure down to the bottom of the squat.
3. As you ascend and pass the "sticking point", usually when the thighs form a 90-degree angle with the knees, you can start a very controlled, slow release of air through nearly closed lips ("tss" sound).
4. Complete exhalation is permitted only once you have locked out the hips and knees in the standing position.

Application to the Deadlift

The deadlift differs because it starts from a dead stop without a preceding eccentric phase:

1. Set your feet and hands on the bar while on the floor.
2. Before pulling, draw air into your belly, lock the glottis, and engage your back muscles to pull the slack out of the bar.
3. Keep your breath locked throughout the entire path of the bar from the floor to the knees.
4. Once past the knees and the hips drive forward, you can exhale gradually as you complete the lockout of the shoulders and pelvis.
5. If performing multiple repetitions without letting go of the bar, take the new breath at the top of the movement before lowering the bar, or on the floor between reps. For heavy sets, resetting and taking a new breath on the floor is the safest option.

Contraindications for individuals with cardiovascular wellness

The Valsalva technique produces exceptional mechanical stability, but it carries a significant cost for the cardiovascular system. During the straining phase with a closed glottis, pressure inside the thoracic cavity rises dramatically. This compresses the large veins, particularly the superior and inferior vena cava, temporarily reducing venous return to the heart. Immediately after, to overcome this resistance, the heart contracts with greater force.

In healthy athletes, systolic blood pressure can momentarily rise from a normal 120 mmHg to values above 260 or even 320 mmHg during a maximal squat. This acute response is normal and well tolerated by a healthy vascular system. However, for individuals with diagnosed arterial cardiovascular wellness, the condition is dangerous.

The following medical conditions represent absolute or relative contraindications to using a full Valsalva maneuver:

• Stage 2 or uncontrolled cardiovascular wellness: The sudden pressure spike strains vascular walls and increases the risk of an acute cardiovascular event.
• History of aneurysm: Whether a cerebral aneurysm or an aortic aneurysm, the sudden spike in arterial and intracranial pressure increases the risk of rupture.
• Ophthalmic conditions (glaucoma, retinal detachment): Increased intrathoracic pressure is transmitted through the venous system to the capillaries of the eyes, causing subconjunctival hemorrhages or worsening intraocular pressure.
• Hernias (inguinal hernia, umbilical hernia): Extreme intra-abdominal pressure can push internal organs through weakened spots in the abdominal wall, aggravating an existing hernia.

If you have a history of cardiovascular problems, lifting maximal loads with a full Valsalva maneuver should be avoided. In these cases, training should be performed with lighter loads (under 70% of maximum) and continuous, rhythmic breathing. Consult your attending physician or a cardiologist before using closed-glottis techniques under resistance.

Common technique mistakes

Applying the Valsalva maneuver seems simple in theory, but in practice, specific mistakes are made that reduce its effectiveness:

• Chest breathing instead of diaphragmatic breathing: The lifter takes in air by lifting the ribs and shoulders upward. This fills only the upper part of the lungs, leaves the abdomen without pressure, and alters the position of the upper spine.
• Inhaling an excessive volume of air: Filling your lungs to full capacity causes overexpansion, makes abdominal contraction difficult, and sharply increases the risk of dizziness. An air intake around 80% is ideal.
• Stomach hollowing: Instead of pushing the abdominal wall outward against the belt, the lifter pulls the navel inward. This movement reduces the base of support and destabilizes the pelvis.
• Releasing air at the bottom of the movement: Losing air at the lowest point of the squat leads to a loss of torso tension, "rounding" of the lower back, and an inability to drive out of the hole.

Practical implementation steps for training

To integrate the Valsalva maneuver properly into your next workout, follow these specific preparation steps:

Unweighted floor drill: Lie on your back with your knees bent. Place your hands on the sides of your waist, right below your ribs. Inhale through your nose and direct the air straight into your fingers, causing them to push apart. Tighten your abdominals without changing the position of your lower back on the floor. This is the feeling of proper bracing.

Practice during warm-ups: Do not wait until you reach heavy working sets to use the technique. Apply the Valsalva maneuver from your first warm-up sets with the empty 20 kg barbell. Coordinating your breath and movement must become automatic before heavy loads are added.

Managing post-set dizziness: Once you rack the bar, do not sit down immediately and do not walk away quickly. Take three or four deep, rhythmic breaths while resting your hands on your knees or the rack. This allows cardiovascular function and heart rate to normalize smoothly, preventing orthostatic dizziness and fainting.