There is a strong belief in our western culture that a constant holding in of the belly keeps the abdominal muscles strong. This belief rides in tandem with the idea that a pulled-in abdomen, or "flat" stomach, looks better. Media, whether social, magazines, movies, or entertainment, still predominately feature slender, "tight bodied" people with small waists and visible abdominal muscles as a health and fitness ideal. Waist trainers, girdles, and corsets remain a viable and popular industry (like Spanx and Skims). Unfortunately, most of us already walk around with our own internal, psycho-emotional girdle that keeps our stomachs rigid and pulled inward without even realizing it.
The cells of our bodies desire to breathe. When air enters our bodies it takes a circuitous path throughout, moving through different passages, chambers, tubes, organs, and gradually branching off into small tributaries until it reaches the cells. Cells require energy and they receive it through the nutrients we eat and a constant supply of oxygen. While the lungs and the heart must work in synchrony with one another to circulate oxygen throughout the body, it is the respiratory muscles that actually draw the air into the body. These muscles are like any other - they can become chronically tight and shortened, they can weaken and have poor tone, and they can move in a distorted way if they are being asked to take over tasks they were not designed to do. As such, the primary respiratory muscles of the diaphragm, intercostals, and abdomen, must work efficiently, in both a strong and relaxed manner, in order to allow the secondary respiratory muscles of the upper shoulders and chest to act in a subordinate role and remain relaxed. When we reverse these roles - as it often happens through poor breathing habits due to strain, stress, trauma, and lack of awareness - and the secondary respiratory muscles are used primarily, it not only causes tension to the upper back, shoulders, and neck, but also decreases the amount of oxygen we draw into our lungs, which can exacerbate or even trigger the sympathetic nervous system (responsible for the fight, flight, or freeze response) and cause us undue anxiety, restlessness, and poor sleep, leading to a cascade of other physical and chemical responses within the body system.
1. Relaxing your stomach will make it bigger.
A strong muscle is a muscle that can also fully release. Holding the abdominal muscles in a constant state of contraction causes them to weaken. In order for any muscle to function effectively it has to completely relax between contractions. This holds true for the abdominal sphere as well; in free breath, the core-centric muscles alternately contract and release, allowing fresh nutrients to circulate through the muscles, and toxic waste products (known as ama in Ayurveda) to be flushed out. This not only keeps the abdominal muscles strong, it helps the body to assimilate and eliminate - both functions necessary for a healthy metabolism and strong digestive fire (agni). Relaxing your abdomen doesn't mean letting it hang out unconsciously, it means letting your belly move so that you experience both the relaxed and toned phases of the breath cycle.
2. Holding the belly will prevent back pain.
If you or someone you know has suffered from back pain you may have heard to keep your abdomen pressed back toward the spine all the time in an effort to stabilize your spine. It is true that a strong abdominal circumference will support the spinal muscles in stabilizing the back and should be used especially when lifting (weights, objects, children, dogs...) to stabilize the spine. However, keeping the abdomen in a constant state of contraction increases the tension and stiffness in the lower back muscles and can increase your pain levels. In traditional medical theories like Chinese Medicine and Ayurveda, the presence of pain indicates energetic stagnation, a lack of free flowing prana or qi. The diaphragm attaches along the front of the lumbar vertebrae, so any constriction in this important breathing muscle will immediately be reflected in the function of the spine (as well as in the ilio-psoas, another muscle that tends to be tight, weak, and very often contributes to spinal pain - this is a reciprocal relationship, thus chronically shortened psoas contributes to a poorly functioning diaphragm). The soft, spongy discs that form a cushion between each vertebrae also require regular irrigation of fluid - the process of which can only happen through movement as there is no direct blood supply to the discs after our early twenties. The breath acts as an internal massage, and has the ability to support the healthy functionality of the spine as a regular, minute by minute source of traction, creating space between the bones and reducing nerve impingement, bone degeneration, and arthritis. Allowing your abdomen to move while you breathe is an effective way to keep your spine healthy.
Reflection - close your eyes feel your breathing. Do your shoulders rise and fall while you breathe? Do you feel constricted through your chest, stomach, or belly? Is your jaw clenched or tight? Take a few long, deep breaths and let go of each exhalation through the mouth. How does it feel when you consciously breathe into your abdomen, as though you could breathe into the bowl of your pelvis? Can you let your shoulders and arms hang heavily and "ride the wave" of the breath without directing it upward?