The softening, stretching, and weakening of the linea alba of the rectus abdominis and the subsequent lateral widening of the rectus muscles are generally, but not exclusively, considered to be caused by pregnancy. This is the case for nearly 90 percent of the maternal population. As the baby grows, the uterus displaces from a pelvic organ to an abdominal organ resulting in stretched and weakened abdominal muscles. For some pregnant women, the rectus abdominis can stretch longitudinally as much as 115 percent.

The pressure against the connective tissue that connects the two sides of the rectus – the linea alba - by the growing uterus as well as the hormonal influences of relaxin, create a separation of the rectus abdominis along the linea alba called the diastasis recti. "Diastasis" is a Latin word that means separation.

This diastasis does not necessarily heal on its own during postpartum recovery. As a matter of fact, in many instances women have a diastasis for the rest of their lives if they don't do appropriate corrective exercises that will repair the separation (or have them surgically repaired which was the technique used to fix severe separations). The sequelae of a diastasis might be chronic backaches and lumbar instability, and in severe cases, ventral or umbilical hernias for anyone, female or male, with this abdominal weakness.

As the baby grows, the maternal rib cage expands as much as 2-3" anterior and lateral. The rectus, which inserts into the 5-7th ribs, also stretches laterally. The same condition occurs at the pubic symphysis, the origin of the rectus. However, the maladaptive posture of pregnancy – anterior pelvic tilt, exacerbated lordotic curve, protracted neck, hyperextended knees, etc. – and the musculoskeletal discomforts that arise from this posture can be minimized with shorter abdominal muscles and a stronger, more intact abdominal core.

A large diastasis during pregnancy can prolong labor. Since core strength is lax, the uterus bulges forward even more, creating a more pronounced lordotic curve and anterior pelvic placement. This is why a second time mother looks bigger earlier in her pregnancy. The fetal head doesn't align within the pelvis as well as it would if the core were strong and intact, and it is more difficult to engage weak abdominal muscles while pushing, so labor often takes longer.

Not Just A Problem For Moms

But you don't have to be pregnant or a mother to have a diastasis. World class athletes and weekend warriors who do the wrong types of abdominal exercises (i.e. crunches or cross over twists) often develop this separation over time. Even Joseph Pilates, the developer of the popular eponymous exercise system, had a diastasis which got bigger as he got older. While many of his exercises target the core abdominal muscles, many of these exercises can contribute to a diastasis.

Carrying excess abdominal fat also puts pressure against the linea alba and can cause a diastasis for men and women. And people with chronic backaches or back issues fail to recognize that back instability often is caused by weak abdominal muscles and a diastasis recti.

Testing for the presence of a diastasis on your clients or on yourself is easy. You are looking for two conditions: the number of fingers that fit inside the separation and the condition of the connective tissue. The connective tissue will be superficial, moderate or deep. The deeper the connective tissue is, the closer it is to the visceral organs and the longer it will take to close the diastasis.

Have your client lie down on their back and with their knees bent. Place your fingertips in the umbilicus and have your client lift their head (not the shoulders) a few times as you press slightly deeper. Feel for the edges of the rectus muscles coming up. The number of fingers that fit in the space between the edges tells you how wide the separation is. A half a finger width indicates no diastasis. A finger or greater indicates there is one.

Now feel how deep your fingers go. If you feel a pulse, the connective tissue is deep and weak. Test three inches above and below the umbilicus, along the linea alba. When you test yourself, assume the same back-lying position and place your fingers pointing down toward your feet. Test at all three areas.

A brief review of abdominal muscle anatomy is important to understand how the action of one muscle affects the others. We have three layers of abdominal muscles: the outermost rectus abdominis, the deeper internal and external obliques, and the deepest abdominal muscle, the transverse abdominis (TVA). The rectus abdominis originates at the crest of the pubis and symphysis pubis and inserts into the costal cartilage of 5th -7th ribs and the side of the xiphoid process. It has two halves that are usually inch apart and are connected by the fibrous linea alba. Relaxing, forward pressure, and the growing uterus cause the linea alba to relax (allowing the muscles to move aside for fetal growth), stretch sideways, and become thinner. This is the diastasis.

The action of the rectus abdominis is trunk flexion, but when standing, it supports the visceral organs, holds the rib cage and pubis together and gives anterior support to the lumbar spine. Along with the gluteus maximus and hamstrings, it prevents an anterior pelvic tilt. Since this muscle is so compromised during pregnancy, it is easy to see how weakness in this muscle affects the entire core support and initiates the maladaptive posture associated with pregnancy.

The obliques are the middle layers of the abdominal core. The anterior division of the external obliques originates on the anterior surfaces of the 5th-8th ribs and inserts at the linea alba (as a broad abdominal aponeurosis). The lateral division of the external obliques originates at the lateral anterior surfaces of ribs 9-12 and inserts into the iliac crest along the outer lip. This group, along with the internal obliques, aids in trunk flexion and, when working unilaterally, rotates the trunk and flexes the trunk laterally. Since they attach to the rectus via the linea alba, it is easy to see how a rotational force pulls on the linea alba and stretches it even more. That is why cross-over abdominals do more harm than good.

The internal obliques cross in the opposite direction. The anterior division of the internal obliques originates in the inguinal ligament and medial lip of the pelvic crest and runs up and inserts at the crest of the pubis and linea alba (by the aponeurosis). The lateral division originates at the middle 1/3 of the iliac crest and inserts at the inferior borders of ribs 10-12.

The deepest abdominal muscle, the transverse abdominis, wraps around the abdomen and back like a belt or a girdle. It originates at the lateral 1/3 of the inguinal ligament, anterior 3/4 of the internal edge of the iliac crest, lumbodorsal fascia and the inner edges of the lower six ribs. It inserts into the – wait for it! – linea alba aponeurosis which passes behind the rectus abdominis. It functions to increase intra-abdominal pressure, assists in forced expiration, defecation, and during labor, stabilizes the lumbar spine and stabilizes the linea alba.

Treatment Technique

Based upon this anatomy, it makes perfect sense – and anatomical logic – that exercises that recruit the TVA are the ones that will make the diastasis smaller. This is even more apparent when you consider that the largest measurement of the diastasis usually is at the umbilicus and the muscle that works the rectus from the middle is the TVA.

The exercises that specifically target the TVA and shrink the diastasis are based upon a system of exercises called the Tupler Technique. The Tupler Technique is a four-step research-based program that includes: 1) specific exercises that isolate and work the TVA; 2) wearing and holding a splint. This splint does much more than the over-the-counter drug store splints or girdles. This specifically designed splint compresses the abdomen and approximates the rectus abdominis, making the exercises more efficient and repositioning the muscle to its correct position; 3) using the TVA with all activities; and, 4) using proper body mechanics when getting up and down from a back-lying position (no jack-knifes allowed).

The position you start in is very important, since the TVA is affected by gravity. The optimum way to begin these core strengthening exercises is in a seated or standing position. The head lifts of the Tupler Technique are only performed once the diastasis starts to heal. Belly breathing puts the TVA in the correct starting and ending position. If you imagine a horizontal elevator, the first floor is a neutral abdomen, the fifth floor is bringing the TVA all the way to the spine, and the sixth floor is an isometric contraction 'out the back'.

It is impossible to engage the TVA to fifth floor and hold it there if you are on your back and your shoulders come off the floor. That is why crunches and sit-ups don't work; they actually cause the abdomen to protrude and make the diastasis larger, the antithesis of what they are supposed to do.

When doing the head lifts of the Tupler Technique, the head comes up with the chin tucked in, as in a nod. And all cross-over exercises and sports (tennis, golf, etc) should be avoided when a diastasis is present because as we saw with the obliques, these forceful movements pull on the linea alba and further sheer it laterally.

The TVA is the missing link in core integrity – whether your client is pregnant, has a mommy pouch, is recovering from abdominal surgery, has a large belly or suffers from back pain and instability. Doing the Tupler Technique, regardless of how long the diastasis is there, will repair the diastasis and create a strong, integrated core.

Resources:

1. Stillerman E, Prenatal massage: a textbook of pregnancy, labor, and postpartum bodywork. Mosby, St. Louis, 2008.
2. Tupler J, RN, Lose your mummy tummy. Da Capo Life Long, Cambridge, 2005.