A New Study "Disproves" hypopressives reduces intra-abdominal pressure. Here's why that doesn't surprise me and what I already knew and teach!

I've tried to break this down and explain it as simply as possible but it's not a simple one to explain! Lols

It is a long one, so grab a tea, have a read and let me know what you think. 

A new study has just been published challenging one of the most widely taught theories behind hypopressives- that the practice reduces intra-abdominal pressure (IAP). Across the hypopressives world, some teachers are rattled. 

My reaction? Not surprised- we already knew this wasn't the purpose of the practice. And here's why.

At the IHC UK, we never built our teacher training around IAP reduction as the primary mechanism. When we developed our course, we went back to basics - we questioned the existing explanations and looked at the actual physics of what happens in the body during a hypopressive practice. What we found was far more interesting than the soundbite that had been circulating for years.

It was never about reducing IAP. It was always about managing it.

This is the distinction that matters - and it's one that the study actually supports rather than undermines.

Hypopressives don't work by reducing intra-abdominal pressure. They work by training the body to manage and distribute pressure more effectively - so that the inevitable increases in IAP that happen during daily life, exercise, coughing, and lifting don't disproportionately load the pelvic floor and its surrounding structures.

That's a more sophisticated goal. And it's a more clinically meaningful one for the clients we work with.

The physics of what actually happens

Let's break down what the physics tells us.

During the hypopressive apnea, we close the mouth and nose, hold the air out and expand the ribs.

When the system is closed and we expand the ribs, we increase volume (make more space) This causes intrathoracic pressure to drop. This is boyles law. 

The expansion of the ribs often draws the abdomen in, which actually maintains or increases pressure in the abdominal cavity- because we're reducing volume in that space. Now you have lower pressure above and higher pressure below - a pressure gradient between the thoracic and abdominal/pelvic cavities.

In any system where a pressure gradient exists, contents move from the high pressure zone toward the low pressure zone. In this case - upward. This is the vacuum, the lift, the suction effect that practitioners and clients can feel. It's not magic. It's physics.

This pressure gradient also helps explain levator ani activation - the lift we observe in the pelvic floor muscles is consistent with the upward bias created by this pressure dynamic.

Pascales and newtons third law further explain what's happening but I shall save that for another day. 

How Hypopressives Actually Manages IAP

So if it doesn't reduce IAP, how does the practice help clients with pelvic floor dysfunction, prolapse, or core rehabilitation? Here's what the evidence and anatomy tell us:

Transversus Abdominis Activation - Ultrasound studies show thickening of the transversus abdominis (TrA) during hypopressives, indicating activation of this deep abdominal muscle. The TrA functions like a corset around the abdominal canister - creating circumferential tension that regulates and distributes pressure rather than simply increasing or decreasing it. This is pressure management at a muscular level.

The Deep Canister System - The TrA doesn't work in isolation. It functions as part of the deep canister system alongside the diaphragm, pelvic floor, core and multifidus. What hypopressives trains is the coordination and timing of this entire system - so that when pressure increases, the canister responds as a unit rather than allowing that pressure to be directed disproportionately downward.

Postural Organisation - Postural alignment is a foundational component of hypopressives that is often underestimated. The specific postural principles of the practice - axial elongation, cervical positioning, rib cage organisation - create tension through the deep myofascial chains. This further supports the canister system and contributes to how pressure is distributed throughout the body.

Pelvic floor activation- The recent study showed levator ani muscles were active during the HEs performed both in supine and in standing. 

• They're involuntarily activating - engaging during the practice rather than being overwhelmed by an increase in pressure

• They're demonstrating the anticipatory activation response that is the hallmark of a well-functioning pressure management system

• They're activating as part of a whole system response alongside TrA, diaphragm elevation and postural organisation - not in isolation

The external anal sphincter muscle activation- The recent study also showed EAS activated.

The EAS is part of the pelvic floor complex. Its activation during hypopressives tells us:

• The pelvic floor is responding as a complete unit - not just the levator ani but the entire sphincteric and supportive system

• This is significant for clients with bowel dysfunction, anal incontinence or posterior compartment prolapse - the EAS is directly relevant to these conditions

• It reinforces the pressure management argument - the entire pelvic outlet is actively closing and resisting during the practice

 External abdominal oblique activation: And guess what the study found this too

• The obliques are part of the outer abdominal canister - they work alongside TrA to create abdominal wall tension

• Their activation suggests hypopressives recruits both the deep and superficial abdominal wall layers

• Together with TrA this creates a much more complete circumferential tensioning of the abdominal canister than TrA alone could achieve

• This multilayer activation means the canister walls are stiffer and more capable of containing and distributing pressure in all directions

So the study actually provides good evidence of IAP management :-)

Let's assess the study in more detail

The study measured IAP during hypopressive exercises in two positions - supine and standing. On average, IAP barely changed in either position, and the results were not statistically significant. But some did increase in IAP and some decreased - let's take a look at what would cause the difference....

During a hypopressive there are two things happening simultaneously that have opposing effects on IAP:

1. The abdominal vacuum  tends to INCREASE IAP - Drawing the abdominal wall inward reduces abdominal volume. By Boyle's Law - reduced volume increases pressure. So if someone's dominant action is pulling the abdomen in strongly, IAP is more likely to increase.

2. Rib cage expansion - tends to DECREASE IAP in the thoracic- Lateral rib cage expansion increases thoracic volume, drops intrathoracic pressure and creates the pressure gradient we discussed. If the diaphragm elevates sufficiently and thoracic expansion dominates, the pressure gradient effect pulls contents upward - potentially reducing IAP.

So individual outcomes depend on:

• Which action dominates in that person's technique - rib expansion or abdominal drawing in

• The ratio between how much abdominal volume decreases versus how much thoracic volume increases

• Anatomical differences - rib cage shape, diaphragm mobility, abdominal wall tone

• Skill and training level - a more experienced practitioner may have better rib cage dissociation and diaphragm control

• Body position - which explains why supine and standing produced different results

Neither outcome - slight IAP increase or slight IAP decrease - may actually matter as much as whether the deep canister is activating coordinately. The LAM, EAS and oblique activation findings suggest the system is responding regardless of which direction IAP moves. YAY!

So how do we manage Intra abdominal pressure? 

1. The deep canister needs to function as a unit - The diaphragm, TrA, pelvic floor and multifidus need to co-activate and co-ordinate - not just be strong individually. Timing matters as much as strength. If one part of the canister is weak, uncoordinated or unresponsive, pressure will find the path of least resistance - usually downward onto the pelvic floor.

2. The pelvic floor needs to be responsive, not just strong This is a really important clinical point. The pelvic floor needs to be able to:

• Pre-contract before a pressure challenge - anticipatory activation

• Yield and recoil appropriately under load

• Relax fully as well as contract

A hypertonic or overactive pelvic floor can manage pressure just as poorly as a weak one - it can't respond dynamically if it's already holding tension.

3. The TrA needs to create circumferential tension Not a bracing or bearing down response - but a gentle 360 degree tensioning that stiffens the canister walls so pressure is contained and distributed rather than directed downward.

4. The system needs to be automatic Ultimately pressure management has to happen reflexively - nobody consciously contracts their pelvic floor every time they cough. The goal of training is to restore automatic neuromuscular responses.

And hypopressives train this through....

➡️ Muscle chain activation

➡️ Fascial tensioning 

➡️ Diaphragm and pelvic floor synergy

➡️ Rib mobility and expansion

➡️ Postural alignment

➡️ Reduced abdominal gripping

➡️ Functional breathing 

➡️ Nerve flossing

What This Means for Your Practice and Your Training

If you've been teaching hypopressives and have felt uncertain about how to explain the science - this is actually a moment of opportunity. The oversimplified IAP reduction narrative was always a weak foundation. The real mechanisms are richer, more defensible, and more clinically relevant.

And if you're a women's health professional, physiotherapist, or pilates teacher who has been curious about hypopressives but hasn't yet trained - this is the conversation that should shape which training you choose. Not all hypopressives trainings are built on the same scientific foundation.

At the IHC UK, this is the level of understanding we bring to every aspect of our teacher training. We don't just teach you how to deliver the practice - we teach you how to understand it deeply enough to explain it, defend it, and apply it intelligently for every client in front of you.