Abs workout essence

In ABS training the most important muscles are: the rectus abdominis, quadratus lumborum, and iliopsoas.

The rectus abdominis is a muscle of the anterior abdominal wall and forms the top layer of muscles in this area. When well-trained and combined with low body fat, it can create a 6-pack appearance. However, anatomical variations can result in 4r- or 8-packs in some individuals. The rectus abdominis is divided by several transverse tendinous intersections. [1] the linea alba, a connective tissue located in the midline of the body, separates this muscle into two flat, parallel muscles. The rectus abdominis originates from the pubic crest and inserts onto the xiphoid process of the sternum and the costal cartilages of ribs V-VII. Its main functions include trunk flexion, compression of the abdominal viscera and expiration (depression of ribs).

The quadratus lumborum (called QL) is a flat, quadrangular-shaped muscle located in the posterior abdominal wall. It is commonly referred to as a back muscle, specifically one of the paraspinal muscles, due to its position in the deep, posterior, lateral, and inferior areas of the spine. [2] QL originates from the iliac crest and iliolumbar ligament and travels superomedially to attach to the transverse processes of lumbar spine (L1-4) and the medial half of the inferior border of the 12th rib. When both sides of the QL contract, it causes extension of the trunk and can act as an accessory muscle for inspiration. When contracted unilaterally, it causes lateral flexion of trunk. The QL is a stabilizer of the lumbar area and is an integral part of thoracolumbar fascia. It forms a lateral myofacial sling which aims to maintain frontal plane stability of pelvis. [3]

The iliopsoas is a large, deep structure in the trunk, comprising 3 muscles: iliacus, psoas major and psoas minor. This complex system is also known as the iliopsoas musculotendinosus unit (IPMU). These muscles can function together as a unit or separately. [4] The psoas minor is sometimes not considered part of the iliopsoas due to its different insertion points (originating from vertebrae T12-L5 and inserting on the iliopectineal eminence). The psoas major originates from the transverse processes and lateral surfaces of vertebrae L1-4 and their associated intervertebral discs. The iliacus originates from the iliac fossa and the lateral part of the sacrum. Together, these muscles attach to the femoral lesser trocheanter. [5]. The primary functions of the iliopsoas muscle are hip flexion and assisting in external rotation. It also plays a critical role in maintaining proper lumbar posture during sitting and standing.

All of these muscles plays a major role in core stability. By default, our nervous system tends to activate muscles by functional proximity, which means that when trying to extend the hips, iliopsoas muscle will choose quadratus lumborum as its core supporter. This tendency to always work together is unwanted, as in the long run, it shifts balance of our core to the back. To adress this, good abs exercises makes sure that lumbar spine is in neutral or even flexed position even before starting to work with hips. Incorporating a hips extension component on top of lumbar flexion, disrupts unwanted muslce co-firing, making exercise a golden one.

  1. Hislop, Montgomery “Daniels and Worthingham’s muscle testing: techniques of manual examination“. Elsiever, 2007, 8th edition
  2. Bordoni, Bruno, i Matthew Varacallo. „Anatomy, Abdomen and Pelvis, Quadratus Lumborum”. StatPearls, StatPearls Publishing, 2024. PubMed, http://www.ncbi.nlm.nih.gov/books/NBK535407/.
  3. Wallden, Matt. „The Middle Crossed Syndrome – New Insights into Core Function”. Journal of Bodywork and Movement Therapies, t. 18, nr 4, october 2014, s. 616–20. DOI.org (Crossref), https://doi.org/10.1016/j.jbmt.2014.09.002.
  4. Bordoni, Bruno, i Matthew Varacallo. „Anatomy, Bony Pelvis and Lower Limb, Iliopsoas Muscle”. StatPearls, StatPearls Publishing, 2024. PubMed, http://www.ncbi.nlm.nih.gov/books/NBK531508
  5. Tatu, L., i in. „Descriptive Anatomy of the Femoral Portion of the Iliopsoas Muscle. Anatomical Basis of Anterior Snapping of the Hip”. Surgical and Radiologic Anatomy: SRA, t. 23, nr 6, 2001, s. 371–74. PubMed, https://doi.org/10.1007/s00276-001-0371-9
ABScoreiliopsoasmuscleQLquadratus lumborumrectus abdominis
Muscles