Modern strength and endurance training are dominated by a prime-mover model of human performance, in which muscles are treated as engines that produce force and the core is treated as a collection of stabilizing muscles to be strengthened or braced. While this model is effective for short-duration outputs, it fails to explain durability, efficiency, and the phenomenon of apparent tirelessness observed in elite endurance performers.
This essay proposes an alternative framework grounded in biomechanics, neurophysiology, and lived movement practice: muscles function primarily as regulators of tension and timing; elastic tissues act as major carriers of load; and the core operates not as a muscle group but as a distributed regulatory field. This reframing clarifies why coordination often outperforms raw strength, why relaxation can increase power, and why endurance emerges from coherence rather than suffering tolerance.
The Problem with the Prime-Mover Model
The dominant model of strength assumes a linear causality:
Muscle contraction produces force → force moves the body.
This model emphasizes hypertrophy, maximal recruitment, and rigid stabilization. While effective for short-duration outputs, it carries hidden costs:
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High metabolic demand
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Excess joint shear
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Early fatigue
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Accumulating micro-injuries
Critically, it fails to scale over millions of movement cycles, as required in ultra-endurance activities such as transoceanic rowing.
Muscles as Tension Regulators
A systems-based view reverses the causal arrow:
Force already exists (gravity, inertia, elastic recoil, pressure); muscles regulate how it is transmitted.
In this model, muscles do not primarily create force. Instead, they:
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Adjust stiffness and compliance
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Coordinate timing across joints
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Prevent collapse or over-bracing
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Shape force pathways through the body
Strength, therefore, becomes a function of timing and distribution, not maximal contraction.
Elastic Tissues as Load-Bearing Structures
Elastic tissues—fascia, tendons, aponeuroses, joint capsules, and even arterial walls—store and return mechanical energy at minimal metabolic cost. When properly loaded:
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Force is spread over time rather than spiked
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Muscular effort decreases
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Structural durability increases
Elite movers preload these tissues early, maintain continuous chains across segments, and allow timely release. Muscles act as governors of the spring system, not engines driving it.
Cardiac, Respiratory, and Locomotor Coherence
At moderate, sustained outputs, high performers exhibit phase alignment among:
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Movement cycles
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Breathing rhythms
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Heartbeat timing
This phenomenon—cardiac–locomotor coupling—reduces neural noise and autonomic cost. Heart rate variability, rather than appearing jagged, organizes into smooth oscillatory patterns driven largely by respiratory sinus arrhythmia. The system stops constantly correcting and begins predicting.
The result is the subjective experience of quiet power and the objective outcome of lower energy expenditure per unit work.
Redefining the Core
From this perspective, the core cannot be accurately defined as a muscle group. A more functional definition is:
The core is the body’s ability to maintain coherent pressure and tension across the trunk while force is transmitted.
As a regulatory field, the core:
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Modulates intra-abdominal and intra-thoracic pressure
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Maintains connective-tissue continuity
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Times stiffness and yielding relative to load
Bracing collapses this field; collapsing collapses it in the opposite direction. Core function lies in maintaining openness under load.
Why Some People Appear Tireless
Individuals who seem tireless at moderate outputs are not simply better conditioned. Their systems:
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Minimize micro-corrections
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Preserve elastic return
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Maintain parasympathetic tone during effort
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Reduce emotional and neural reactivity
Over millions of repetitions, small efficiency gains become decisive. Endurance emerges not from suffering tolerance, but from avoiding unnecessary work.
Key Takeaways
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Muscles regulate tension more than they generate force.
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Elastic tissues are primary carriers of load in efficient movement.
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Strength is about timing, not maximal effort.
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The core is a regulatory field, not a muscle group.
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Endurance depends on coherence across mechanical, respiratory, and cardiac systems.
Reframing strength and endurance through regulation rather than production resolves several long-standing paradoxes in human performance: why smaller or older individuals can feel stronger than younger, larger ones; why relaxation often enhances power; and why coordination scales while effort does not. In this view, force is not something the body must manufacture at high cost, but something it must manage intelligently.
This perspective does not reject strength training or conditioning. Instead, it situates them within a larger architecture where coherence, timing, and elastic return determine whether strength is expensive or cheap, transient or durable. When muscles learn to regulate rather than dominate, elastic tissues resume their role as load carriers, the core regains its function as a pressure–tension field, and endurance ceases to be a test of suffering.
What emerges is a quieter definition of power—one that favors continuity over peaks, prediction over reaction, and sustainability over display. Over minutes this difference is subtle. Over millions of repetitions, it is decisive.
Strength is not the ability to produce force, but the ability to maintain form while force passes through.