Last updated Sep 9, 2019


Core muscles are muscles of the midriff, which wrap around the front and back of the body like a compression wear for the waist. When core muscles contract, they create an intra-abdominal compression which keeps the lumbar spine supported.

The compressive force also creates a tightening effect around the waist, similar to a corset or weightlifter’s belt. Core muscle contraction supports the lower back, and trims the waist, except it is all natural. A belly-toning force that we already have in the body.

Figure 1: Core muscle contraction creates an intra-abdominal pressure, that acts like a compression wear around the waist.

A good diet and regular aerobic exercise to burn excess fat are still the best way to lose weight. Weight loss is a reduction of body mass on all the body parts. The benefit of core exercises is if you find you can’t seem to tone the abdominals no matter how much aerobic exercises you have done, adding core training to your exercise may be what you need.  Core exercises target the abdomen, especially the deep abdominal muscles, which can make a cosmetic difference to the abdomen. Feel trimmer and toner around the waist. As muscles will burn calories even at rest, strengthening your core muscles will also help keep the belly fat away and maintain the waistline. 


Pilates does not hold a trademark on core training. You can also strengthen your core muscles with core exercises with strength exercises like abdominal crunches, sit-ups and planks. Strength exercises are also known as resistance exercises as weights are used to create resistance to increase strength.

In a 2015 study, researchers in South Korea compared Pilates instructors, with strength instructors to test which one of the two training programs generate more core strength. The researchers said both groups were experienced instructors. They were given four exercises that involved lumbar stability to do: “Drawing-in” Manoeuvre, Bridging, Roll-up and One-leg Raise.

The study tested the two groups for TA and internal oblique muscle recruitment, while performing the exercises. The thickness of the muscles were measured using ultrasound scanning.

Figure 2: Pilates vs. Strength coaches who have more core muscles? Bridge, one of four exercises used in the test.


Transverse Abdominis Strength: The Pilates-trained group has significantly more TA muscle than the strength-trained group. They have thicker TA muscle, and are better at recruiting the core muscle for lumbar and hip stability than the strength-trained group.

Internal Oblique Strength: The Pilates- and strength-trained groups have equal internal oblique strength. Internal obliques is the surface muscle above the TA muscle. The researchers concluded the group trained in strength exercises are better at recruiting larger, surface muscles for lumbo-pelvic stability. They have bigger muscles, more muscle hypertrophy, than the Pilates group. The Pilates group, on the other hand, has equally strong internal oblique muscle, but the underlying strength of the internal oblique comes from the TA muscle.

Pilates strengthens core muscles more than strength exercises. Pilates exercises focus on activating the deep abdominal muscles for stability, and as the source for movement. It is why Pilates is an exercise that creates strong but lean muscles.


We often think about core muscles as abdominal muscles, anterior muscles of the trunk. Actually, core muscles include the multifidus, a deep posterior trunk muscle that moves the spine. When the multifidus contracts, it creates a stiffening effect on the trunk, which supports the lumbar spine.

Of the core muscles, the transversus abdominis — TA or TVA in short — is most often mentioned as the muscle that need strengthening to prevent lower back pain.  TA is a deep abdominal muscle under the obliques. Similar to the obliques, TA is a lateral muscle of the abdomen.

In clinical studies, patients with chronic low back pain showed significant delays in the contraction of their TA muscle when performing tasks, compared to people with no back pain. Weak TA also affects the ability of the multifidus, the deep trunk muscle, to contract and support the lumbar spine. Thus, strengthening the TA muscles is important for lumbar stability.

TA muscle is a new discovery. You are unlikely to find TA muscle in the older editions of anatomy books. A body of research from the 1990s, which showed the benefit of strong TA for lumbar stability, sparked the interests in core training. Today, core training is an integral part of physical training. It is broadly used from improving sport performance to the rehabilitation of back pain.


Rectus abdominis — or popularly known as the six or eight packs — because of the distinctive boxes, that the muscle is arranged in, is a surface muscle like the obliques.

Sometimes the rectus abdominis, along with the external obliques and diaphragm, are considered as part of the group of core muscles. By definition, however, core muscles are deep abdominal and spinal muscles under the surface muscles. They won’t include rectus abdominis or external obliques which are surface muscles. The main function of the core muscles is to provide lumbar support. It is why core muscles are also known as “stabilising” and “anti-rotational” muscles.

Surface muscles, on the other hand, perform other functions which are their primary tasks. The rectus abdominis, for example, is mainly responsible for trunk flexion, and the diaphragm for breathing.

Strong rectus abdominis is still a symbol of abdominal strength. The six-pack is very much part of the ideal male physique. Core muscles are more subtle. They are deep and we would need to use ultrasound scanning to detect movement of the TA muscle for example. But they are important for lumbar stability, crucial in the prevention of low back injury.

There is a direct co-relation between strengthening core muscles and the reduction of back pain. For patients with chronic low back pain, some 20 hours of Pilates have shown to reduce back pain and improve functional movement.


Core muscles also makes the rectus abdominis and obliques stronger. The core is like the foundation that keeps a house strong. A house needs a strong foundation to withstand bad weather and to last for years to come. Strengthening core muscles with exercises prevent abdominal injury, and allow the abdomen to heal naturally when there is a trauma.

Diastasis recti is a dysfunction of the rectus abdominis, where there is a separation of the rectus abdominis muscle at the linea alba, the centreline of the abdomen. Diastasis recti occurs more frequently in women than men, and usually during pregnancy or postpartum where abdominal muscles are stretched and weak.

When diastasis recti occurs in men, it happens more often in men who are active and fit. Weight-lifting, repeated sit-up exercises and weight swings are common causes of diastasis recti in men. The separation tends to occur overtime, unlike for women where the trauma of childbirth creates the stress on the rectus abdominis. Other causes of male diastasis recti are gastrointestinal disorders, advancing age and weak abdominal muscles.


Strengthening core muscles prevent diastasis recti and promote the recovery from the trauma. Although studies are preliminary, the effect of core exercises on women with diastasis recti are promising. The natural tightening of the abdomen when core muscles contract is also good knitting force to close-up the separation, as well as repair tears on the abdominal wall.

US-based Carolyne Anthony, who specialises in women’s health, teaches Pilates to women with diastasis recti. Women who practiced Pilates, with specific breathing taught by Anthony, experienced visible narrowing of the separation at the linea alba.

Figure 3: Diastasis recti affects two out of every three pregnant women. Pilates has shown to help.

Pilates exercises and breathing also benefit women with stretch marks and scarring tissues from childbirth. Women who have had a Cesarean delivery reported visible reduction in the number of scars at the abdomen after the exercises.

Similar results were seen in a study, published earlier this year, to investigate if deep core stability exercises would benefit postpartum women with diastasis recti. The core stability exercises used in the study were abdominal bracing (with the aid of a large towel to tighten the abdomen,) diaphragmatic breathing, pelvic floor contraction, plank and isometric abdominal contraction. The exercises were performed three times a week for eight weeks.

Women who practiced the core exercises for eight weeks experienced significant decrease in the inter-recti separation, compared to women who were given traditional abdominal exercises. Core exercises have the potential to be a good non-surgical solution for diastasis recti, said the researchers from Egypt and Saudi Arabia.


While diastasis recti and abdominal scars are not life-threatening, but repairing them can bring immeasurable joy. Wearing a bikini again or not having a woozy feeling in the abdomen can feel like a life-saver for many.

Although core exercises are often practiced to strengthen the lower back, training core muscles have other benefits. Strong and active core muscles have a natural slimming effect on the waistline, and they are the underlying strength of the rectus abdominis. They made the rectus abdominis more ready to withstand the stresses we placed on the abdomen. Whether it is weightlifting, or childbirth for women, there are reasons for a stronger core.

Try a Pilates session today. Find your core.

Medical Disclaimer: Always consult your physician if you have an existing pain or a pre-existing medical condition before beginning any exercise. The above information is not intended to diagnose any medical condition or replace your healthcare professional.

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