Differences between Intra-abdominal pressure and Outer Abdominal Bracing

Intra-abdominal pressure holds important fundamental benefits by creating stability of the joints, visceral support and lifting/moving safely, which greatly reduces chances of injury.

In my experience, most of us who exercise (including me in the past) are unaware how to generate intra-abdominal pressure (IAP) and instead produce what I call, “outer abdominal bracing (OAB).

Before I explain the difference, I must state there are contrasting opinions on this topic. Perhaps, partly due to the body’s infinite and complex reverberations and expressions that speak to the individual based on their area of focus, underlying intentions and where one is within themself and their life journey. 

From my own experience and what I understand today is quite different to what I understood in the past; suffice to say this is my truth today that could possibly change tomorrow, however some of the basic mechanical principles and functions of the body will always remain the same.  I offer my view from from 23 years of assiduously healing my self, many hours of study, a big heart to learn and helping countless others heal themselves.

Intra-abdominal pressure, from an exercise perspective, is when the body creates an inner pressure from simultaneously engaging the inner and outer muscle units in movement.

The inner or deeper tonic muscles are called transversus abdominis (TVA),  partial fibres of internal obliques, multifidus, diaphragm and various muscles within the pelvic region.

The outer muscles, which are the more superficial phasic muscles and work in concert with those tonic muscles to produce IAP are the rectus abdominis (RA), partial fibres of internal obliques, external obliques, erector spinae, glutes, hamstrings and adductors.

The inner and outer units have different but equally important roles and functions. The inner unit creates joint stability, postural integrity in movement and the outer unit assists in moving the body through space. To keep it simple, I will remain with the TVA and RA muscles, as this article is more about understanding the elemental relationship exchange between them rather than the scientific musculoskeletal details. 

IAP also increases proprioceptive and kinesthetic feedback, which potentially creates a greater bodily awareness for greater functional development.

Firstly, Intra-abdominal pressure has some important fundamental benefits, by producing spinal and sacroiliac joint stability, as well as visceral protection and greatly enhances the potential for postural improvements and bio-motor development (balance, coordination, strength, stability, flexibility, agility). There are other esoteric benefits too, but that’s for another blog.

IAP is produced when the TVA is activated by drawing the navel inward towards the spine. The viscera then move up into the diaphragm and down into the pelvic floor. This reduces visceral stress, allows space for spinal stability and brings safety in lifting and movement which has a higher resistance. Movement that has a light resistance or minimal physical demand does not necessarily require IAP, as the body can safely maintain integrity without it.

AP is the fundamental principle for progress, as faulty or improper movement patterns usually lack this crucial piece of the healing puzzle and without it, there is limited awareness to feel, sense and discern how the body is moving or oriented in space.

The breath plays a crucial role, because upon inhaling correctly, it produces tension or a lift force within the diaphragm to produce the IAP for reduction of joint/disc stress by as much as 40% according to the findings of Rolf Wirhed in Athletic Ability and the Anatomy of Motion.

When performing a resistance movement, with inhalation the tongue is held in the roof of the mouth to optimize diaphragmatic response, especially within the stomach region and held throughout the resistance phase of the lift before being released through pursed lips when the lift is complete.

Some people make the mistake of exhaling when lifting through the resistance phase. This may be applicable with a lighter resistance or when performing martial art type movements, but for weight training and greater physical demands, the body is potentially  vulnerable to injury with inadequate or no inner integrity and protection of the joints. 

lack of IAP causes decreased bodily awareness to really define trueness of movement, thus the tonic muscles are needed to guide, support and teach the superficial muscles to move correctly from the inside out for optimal motor programming. 

Coming from years of teaching movement, IAP is the fundamental principle for progress, as faulty or improper movement patterns usually lack this crucial piece of the healing puzzle and without it, there is limited awareness to feel, sense and discern how the body is moving or oriented in space. Creating inner pressure in movement enables one to make new neuromusculoskeletal connections, establish a better mind/body cohesion and enhance biomotor abilities.

Remember, IAP also requires that the rectus abdominis and the other phasic muscles mentioned earlier create a counterbalancing effect with the inner muscles. Without this inner/outer muscle counterbalancing, good form principles, and breathing in rhythm with the movement, IPA is not possible, which leads me into the opposite effect or outcome of outer abdominal bracing (OAB).

(OAB) which is essentially contraction and distention from the superficial abdominal muscles without response of the inner muscles. As previously mentioned, lack of IAP causes decreased bodily awareness to really define trueness of movement, thus the tonic muscles are needed to guide, support and teach the superficial muscles to move correctly from the inside out for optimal motor programming. 

Richardson et al (2002) has demonstrated that specific low threshold recruitment of the transversus abdominus is more effective at stiffening the sacroiliac joint and potentially all joints) than merely bracing with the global trunk muscles.

Wearing a weight belt or back brace is usually an indication that back pain is present — Therefore, discovering your natural inner weight belt is the only real answer to healing the body.

To better explain OAB, if one is just pushing against the RA or six pack muscle and other phasic muscles, there is inadequate inner muscle recruitment, leaving the joints unstable and the viscera unprotected. One has to gently draw the navel into the spine to produce IAP which then brings reciprocity and co-activation of the inner and outer muscle to counterbalance one another. Ultimately, outer abdominal bracing produces inefficient weight transfer and inadequate attenuation from trunk and ground forces, to remain in balance and integrity whilst moving.

Take the example of using a weight belt or back brace, the body will automatically push or distend against the belt pressure, destabilizing the system even more, due to the unnatural or adverse muscular activity that a belt will cause.

Wearing a weight belt or back brace, whether at work, gym or general everyday living is usually an indication that back pain is present, as most wouldn’t feel the need for a belt unless that was the case.

Therefore, discovering your natural inner weight belt, consisting of the aforementioned co-activity of inner and outer muscles groups is the only real answer to healing the body.

This is a brief and simplified summary of a complex topic, so we will revisit this topic in more depth in an upcoming blog.

Author: EsoWD

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