Core Curriculum

It makes me cringe any time an athlete, sport coach, or fellow strength and conditioning professional mutters the words “core training.”

Most often, athletes refer to their anterior core muscles, such as the rectus abdominus and internal and external obliques. Sport coaches may blindly state that directly training the core musculature is the singular most important aspect of a strength and conditioning program. Strength and conditioning professionals, including seasoned veterans with many years in the trenches, might find themselves hard pressed to provide rationale for core exercises that they're programming for their athletes. Some coaches might not even specify the exercises and simply type in “core” in italicized 18-point font on the athletes' workout card, often leaving the athletes to their own devices to carry out their training. Furthermore, athletes, sport coaches, and strength and conditioning and fitness professionals might be challenged to define the core and what muscles comprise it. Fortunately, you, the reader, will be supplied with a brief yet detailed refresher on functional anatomy.

The core, which includes the trunk musculature of the lumbo pelvic hip complex (LPHC), encompasses a complex network of muscles that work in constellation to provide multiplanar stability throughout a continuum of activities ranging from household chores to athletic movements. The trunk muscles of the LPHC, which produce an array of movements including flexion, extension, lateral flexion, and lateral rotation, also resist those movements in anti-flexion, anti-extension, anti-lateral flexion, and anti-lateral flexion. The muscles of the LPHC dually support physiological and kinesiological functions. The anterior muscles of the LPHC, namely the abdominals, support and protect the internal organs and help to increase intra-abdominal pressure, which not only increases power output during physical exertion but helps with digestive and respiratory functioning. The musculature of the LPHC also provides the trunk dynamic and segmental stability, supporting posture and absorbing and generating movement.  The muscles also stabilize the lumbar spine, limiting segmental movement and helping to prevent injury during the execution of heavy lifts and during collisions, whether intentional or incidental, in sport competition or practice. Establishing proximal stability of the trunk has been theorized as a means of preventing injury to the distal lower extremities. In conjunction with hip stability, trunk stability has been proven as effective in reducing the likelihood of injuries of the lower extremities.

Deep trunk musculature

The muscles share numerous functions. For instance, the diaphragm and intercostals assist with inspiration and help stabilize the trunk.

Anterior lateral trunk musculature

  • The rectus abdominus (RA), which shares attachment points at the base of the sternum along the cartilage of the fifth, sixth, and seventh ribs, and the pubic bone, flexes the trunk while resisting trunk extension.
  • The external obliques (EO), which share attachment points along the lateral sides of ribs four through twelve, iliac crest, and linea alba, initiate contralateral or opposite side rotation, assist with flexion of the trunk, and resist trunk extension and rotation.
  • The internal obliques (IO), which have multiple attachment points including the iliac crest, inguinal tract, thoracolumbar fascia between ribs seven and nine, and the linea alba, initiate ipsilateral or same side rotation, aid with the flexion of the trunk, and resist trunk extension and rotation.
  • The transverse abdominus, (TvA), which was worshipped by the functional training crowd a decade ago as the 'be all end all' to back and hip pain, shares similar attachment points with the internal obliques, overlapping their insertion points on the ribcage between the sixth and twelfth ribs. The TvA stabilizes the hip while helping create intra-abdominal pressure.

Posterior trunk musculature

  • The spinal erectors or erector spinae (ES) group, which includes the iliocostalis, longissimus, and spinalis muscles, spans from the transverse process of the axis (second cervical vertebrae) to the lumbrosacral joint (L5-S1). The ES serves to extend the trunk and prevent anterior trunk flexion.
  • The transversospinales (TSS), which includes the multifidus, semispinalis, and rotatores, shares multiple attachment points along the spine, providing segmental stability at each region. Collectively, they resist movement at the lumbar spine.

Lateral trunk musculature

  • The quadratus lumborum (QL), which attaches to the iliolumbar ligament, iliac crest, and twelfth rib and shares multiple insertions along the lumbar spine, initiates and resists lateral trunk flexion.
  • Not to be excluded is the thoracolumbar fascia (TCF), which is a gigantic swath of tissue with three tiers that links the trunk muscles of the LPHC with the lats and the glenohumeral joint, providing requisite stability to permit athletic movements. Think of the TCF as the glue that allows the trunk muscles to work synergistically with the hip musculature and the muscles of the upper back and arms.

Trainee mistakes

Not understanding flexion: Novice gym goers and young athletes seemingly will perform trunk flexion exercises as a standalone. Their training sessions are often typified by what they’ve picked up in observing others at the gym. Trunk flexion exercises are most common and consist of sit-ups, crunches, and leg raises (both straight and bent legged). Routinely implicated as begetting injury by strength and conditioning and fitness professionals, trunk flexion is a movement that healthy spines can safely handle. However, repeated trunk flexion may induce compressive forces on the anterior side of the intervertebral discs. In aged populations, those with degenerative spinal conditions, those stuck in prolonged suboptimal static posture throughout the bulk of their day, or those performing flexion exercises with an excessively heavy load, the likelihood of vertebral slippage occurring sharply increases. The compressive forces will cause the nucleus pulposus, the gel like center of the disc that serves as a shock absorber, to migrate posteriorly, which may cause impingement of neurovascular structures including the spinal cord and nerve roots.

Performing rotary trunk exercises: The architecture of the lumbar spine does permit flexion. However, it isn’t built to handle lateral rotation. Throughout the five discs of the lumbar spine, only ten to fifteen degrees of rotation can be attained. Shearing forces from the rotation eat away at the annulus fibrosus, the collagen structure that encapsulates the nucleus pulposus. Repeated shearing forces cause delamination of the annulus fibrosus, which may cause the leakage of the nucleus pulposus into the annular fibers. So it’s wise to avoid oblique twists, weighted and unweighted, for good. Gym owners should also consider scrapping the rotary trunk machines, and manufacturers should strongly consider bringing strength coaches, athletes, and those with a thorough understanding of biomechanics in before designing another $5,000 heap of garbage.

Practical considerations

Few gym goers train the trunk in its anti-movement qualities. Learning how to stabilize the core, which according to McGill can be achieved at just 25 percent of maximal voluntary contraction, will help folks stave off injury and improve their performance in lifts. Lifts that are tested in competition, such as the squat, bench press, and deadlift in powerlifting meets as well as the clean and jerk and snatch in Olympic events, require that the athlete keep a neutral spine that isn't flexed nor excessively extended.

Coaches should start specifying what their program’s “core training” entails, and if they can’t, they should refrain from including it in the athlete’s workout.

For coaches and athletes who need some ideas on where to start, I have compiled a list of my favorite trunk exercises.

  • Loaded carries: I could break this down into a variety of subcategories. I’ll have my athletes perform bilaterally and unilaterally loaded farmer’s walks with dumbbells, kettlebells, and barbells. I will also use plates and sandbags, and I have my athletes alter their hand placement, as in the case with offset grips on a barbell or dumbbell. You could also lump loaded walks, such as high bar and low bar placement walks, yoke walks, and walks with a load extended overhead as loaded carries. Offset loaded barbell walks aren't any walk in the park, as are waiter walks, cross body walks, and cross body lunges.
  • Overhead press variations: For the non-throwing athlete or for the shoulder pathology free client, I’ll have them perform overhead presses from tall, half kneeling, lunge, and seated on the floor positions. Ben Bruno-inspired landmine combination press exercises where a lunge variation and press are tied in simultaneously are really tough, as are your standard military, overhead, or push press exercises.
  • Suspension training: This includes inverted rows, slides, anti-rotation presses, and fall-outs that can be performed with a variety of implements including bars, rings, blast straps, ropes, or TRX equipment.
  • Plank variations: Throwing in pertubations, such as having an athlete or client perform a plank on a Swiss ball while you tap and jostle the ball, presents a unique and deceivingly hard challenge. Agitations can be performed by looping bands around the torso of an athlete and flossing the band around their body, trying to pull them out of the plank position.
  • Unconventional pulls: Suitcase rack pulls and deadlifts challenge anti-trunk flexion and rotary stability, as do shovel rack pulls and deadlifts.