Core Stability: Why the Concept Persisted, Why It Misleads, and What Modern Trunk Training Should Actually Look Like

For more than two decades, core stability has been one of the most widely used concepts in sport science and rehabilitation. It appears in clinical assessments, warm‑ups, physiotherapy prescriptions, and performance programs. It is invoked to explain pain, prevent injury, and enhance athletic performance. Yet the more closely we look at the origins of the idea, the less coherent it becomes. The trunk was never a special subsystem requiring isolated activation. However it became the victim of a commercial narrative that outpaced the science.

Understanding how this happened is not an exercise in debunking for its own sake. It is a way to build a more accurate, integrated framework for trunk training—one that reflects contemporary biomechanics, motor control, and coaching practice.

1. How the “Core” Became Exceptional

The modern core‑stability narrative began with a narrow set of motor‑control studies in the mid‑1990s. Hodges and Richardson observed delayed activation of the transversus abdominis (TrA) in individuals with recurrent low back pain (Hodges and Richardson, 1996; 1998). At the time, this was a reasonable and interesting finding: pain appeared to alter anticipatory postural adjustments. But the interpretation quickly expanded beyond the data. The TrA was framed as a unique stabilizer. The spine was described as inherently unstable. And the idea that deep‑muscle timing deficits caused pain became embedded in clinical education.

The problem was not the original research—it was the generalization.

Later work showed that altered muscle timing is a normal protective response to pain, not a pathology (Hodges and Tucker, 2011). Similar changes occur throughout the body after injury, not just in the trunk. And no evidence ever demonstrated that isolated TrA training prevents or resolves pain (Lederman, 2010).

Yet the narrative stuck. It was simple, intuitive, and commercially attractive. The trunk became a linguistic outlier: a “core” whose dysfunction supposedly explained everything from back pain to poor running mechanics. We did not deserve the same level of attention to “knee stability” or “shoulder stability” even though those joints also rely on coordinated neuromuscular control. The role and function of the trunk has been granted a different status mainly because early findings were overinterpreted and amplified.

2. Why the Trunk Was Never a Stability System

Modern biomechanics tells a very different story. Trunk stability is not the output of a single muscle or a small group of “local stabilizers.” It is an emergent property of distributed, task‑dependent neuromuscular coordination (Cholewicki and McGill, 1996). The spine is stabilized by the interaction of global musculature, passive structures, and neural control strategies that vary with load, speed, and direction (McGill et al., 2003).

More importantly, the trunk’s primary role in athletic movement is not to remain rigid. It is to transmit force between limbs. Kibler, Press and Sciascia (2006) described the trunk as a kinetic‑chain conduit: a structure that must modulate stiffness rapidly to allow efficient transfer of rotational, linear, and shear forces. Too little stiffness and force leaks; too much stiffness and movement becomes inefficient.

This is where the old core‑stability model breaks down. It assumes that stability is a static property—something achieved by activating deep muscles or maintaining a neutral spine. But in sport, stability is dynamic. It is the ability to adjust stiffness at the right time, in the right direction, and in the right magnitude. It is coordination, not contraction. It is variability, not rigidity. And it emerges from whole‑body behavior, not isolated muscle activation.

Pain science reinforces this view. People in pain often adopt protective strategies—co‑contraction, reduced variability, increased stiffness—that feel like “stability” but actually reflect threat perception (van Dieën et al., 2019). These strategies are not deficits to be corrected by hollowing or bracing. They are adaptations that resolve when load tolerance, confidence, and movement variability improve.

3. Planks, Hollowing, and Bracing: What These Exercises Actually Do

The popularity of core‑stability narratives shaped the exercises we prescribed. Planks, hollowing, and bracing became universal solutions. But their mechanisms—and their limitations—are rarely discussed.

Planks

The plank is commonly promoted as a low‑load, neutral‑spine stability exercise. In practice, however, it still generates meaningful spinal compression through isometric co‑contraction. McGill’s modeling work (2007) places the front plank in the ~2,000–2,300 N range. For individuals with sensitized tissues, this can provoke symptoms.

The issue is not the plank itself but the context. Sustained rigidity reduces movement variability, a factor consistently associated with pain persistence (van Dieën et al., 2019). Many people also hinge at the lumbar spine, shifting load toward the extensors (Steele, Bruce‑Low and Smith, 2014). And when the exercise is framed as a way to “protect the spine,” individuals often brace excessively, reinforcing threat perception rather than resilience (Moseley and Butler, 2015). Planks are a tool, not a default exercise. They suit some contexts and irritate others.

Hollowing

Hollowing (“drawing in”) was designed to selectively activate the TrA. But selective activation is not possible during functional tasks (Allison, Morris and Lay, 2008). Hollowing reduces activation of global stabilizers and decreases spinal stiffness under load (Grenier and McGill, 2007). It has limited value outside low‑load rehabilitation and no relevance for performance.

Bracing

Bracing increases intra‑abdominal pressure and trunk stiffness. It is essential under high loads—heavy lifting, sprint starts, collisions—where force transmission demands are high (Vera‑Garcia, Grenier and McGill, 2000). But habitual bracing is counterproductive. It increases compressive load (McGill, 2007), reduces variability (van Dieën et al., 2019), and reinforces pain‑related guarding (Falla and Farina, 2007).

The key is timing: stiffness is a tool, not a posture.

4. Unstable Surface Training: Why It Became Popular in the Core Stability Concept, and Where It Fits

Unstable surface training (UST) rose alongside the core‑stability narrative. Increased EMG activity on BOSU balls and Swiss balls was interpreted as improved stability. Instability became synonymous with functional training. But this interpretation confuses neural effort with functional output.

Instability increases co‑contraction and EMG amplitude, but it reduces force production, rate of force development, and movement velocity (Behm and Anderson, 2006). These effects are particularly evident in lower‑body tasks. Anderson and Behm (2005) showed that unstable squats significantly reduce force output. Kibele and Behm (2009) found that instability impairs jump performance and does not transfer to sport‑specific balance. Granacher and colleagues (2013) demonstrated that core‑instability strength training improves balance in novices but does not enhance athletic performance.

The reason is simple: athletic balance is not about standing on unstable surfaces.

It is about managing perturbations on stable ground—opponents, collisions, rapid decelerations. Balance is task‑specific and context‑specific (McKeon and Hertel, 2008). UST trains slow, ankle‑dominant strategies that do not resemble the demands of sport.

This does not mean UST is useless. It has a clear role in early rehabilitation, particularly after ankle sprains, where sensory reweighting and low‑load challenges are appropriate. But it is not a performance tool, and it should not be used to train trunk function.

5. The Real Framework: Trunk Strength, Control, and Force Transmission

If the core stability model is outdated, what replaces it? The answer is not a new buzzword but a shift in perspective. The trunk is not a subsystem to be activated, however it is a force‑transmission structure whose behavior emerges from whole‑body coordination.

A modern framework focuses on three pillars:

1. Trunk strength: the ability to generate and transmit force under load. This includes hip‑dominant strength (RDLs, split squats, deadlifts), loaded carries, and anti‑rotation work. These exercises build the capacity to handle load without relying on excessive rigidity;

2. Stiffness modulation: the ability to adjust stiffness rapidly based on task demands. Sprinting, jumping, throwing, and change‑of‑direction tasks all require brief, high‑stiffness windows followed by relaxation. This is trained through dynamic tasks instead of static holds;

3. Lumbopelvic control: the ability to coordinate trunk and pelvis during whole‑body movement. Medicine ball throws, rotational sequencing, perturbation‑based drills, and sport‑specific patterns develop this quality far more effectively than hollowing or unstable surfaces.

This framework aligns with contemporary biomechanics and coaching practice by integrating the trunk back into the kinetic chain rather than isolating it.

Conclusion: Letting Go of the Myth While Embracing the Past

The core stability concept persists because it is simple, intuitive, and deeply embedded in clinical and fitness culture. The trunk is not fragile, and it does not require isolated activation, hollowing, chronic bracing, or unstable surfaces to accomplish its tasks and functions in sports performance.

The trunk needs strength, coordination, variability, and context‑specific robustness.

These qualities emerge from whole‑body training, not from chasing isolated muscle activation.

Reframing the concept of core stability in today's sports performance industry is about aligning our language and methods with contemporary science and biomechanics. It is about giving coaches and clinicians a framework that reflects how the trunk actually behaves in sport and life.

And it's about replacing the old narrative of the core as a fragile element requiring special attention with a model built on adaptability, load tolerance, and human robustness.

References

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Antonio Robustelli is the mastermind behind Omniathlete. He is an international high performance consultant and sought-after speaker in the area of Sport Science and Sports Medicine, working all over the world with individual athletes (including participation in the last 5 Olympics) as well as professional teams in soccer, basketball, rugby, baseball since 23 years. Currently serving as Faculty Member and Programme Leader at the National Institute of Sports in India (SAI-NSNIS).