Strength: Why It’s Not Just About Muscle Size

In popular imagination, strength is often synonymous with muscular bulk. While larger muscles typically offer a greater potential for force production, strength is far more nuanced and multifaceted than mere size. It is the product of a complex interplay between muscular, neural, biomechanical, psychological, and metabolic factors. Understanding these components helps explain why a smaller lifter can sometimes outlift a seemingly more muscular one—and why elite strength is as much about efficiency and coordination as it is about mass.

Muscle Size and Force Production: The Foundation

Muscle cross-sectional area (CSA) is positively correlated with maximum voluntary force production. This relationship is well established (Maughan et al., 1983; Akima et al., 2001). Hypertrophy increases the number of actin and myosin filaments per fibre, increasing a muscle’s capacity to generate force. However, this capacity does not guarantee maximal output, because a host of other systems influence how effectively that force can be expressed.

Neural Contributions: Force Without Mass

Neuromuscular efficiency plays a vital role in strength. Strength gains in the early stages of resistance training (within the first 4–8 weeks) occur largely through neural adaptations rather than increases in muscle size (Moritani & deVries, 1979).

Key neural factors include:

• Rate coding: The frequency of motor neuron firing.

• Motor unit recruitment and synchronisation: Effective sequencing of motor units for maximal fibre engagement.

• Intra- and intermuscular coordination: The harmonious action between and within muscle groups.

These adaptations improve the nervous system’s ability to generate and direct force, explaining how trained individuals often display remarkable strength with modest muscle growth.

Anatomical Leverage: The Role of Limb and Tendon Lengths

An individual’s anatomical proportions significantly affect mechanical advantage in lifting tasks.

Limb Lengths and Leverage

Biomechanically, shorter limbs often provide a mechanical advantage. For instance:

• A person with short femurs relative to their torso will typically squat more efficiently, as their centre of mass stays over the mid-foot with less forward lean.

• Conversely, a long-armed lifter may struggle with bench pressing due to a longer bar path but excel in deadlifting where greater reach reduces the range the bar must travel from the floor.

These lever-based differences were discussed in detail by Sell et al. (2007), who noted how anthropometrics influence movement economy and force application in athletic contexts.

Tendon Insertions and Moment Arms

The position of a muscle’s tendon insertion can greatly affect its leverage. A more distal insertion point (further from the joint) increases the moment arm, allowing the muscle to produce more torque with less force.

A classic example: Two individuals with identical biceps strength but different insertion points will curl different weights. The one with the more distally inserted biceps tendon can lift more due to improved leverage—despite having no difference in muscle mass or fibre type.

Muscle Architecture and Fibre Type

Muscle architecture refers to how fibres are arranged within the muscle:

• Pennation angle (the angle between fibres and the force-generating axis) can influence force capacity.

• Muscles with larger pennation angles pack more fibres into a given area, boosting potential force output (Kawakami et al., 1995).

Moreover, fast-twitch (Type II) fibres generate more force than slow-twitch (Type I) fibres. Hence, two muscles of identical size may produce very different forces depending on fibre composition.

Psychological, Metabolic and Technical Variables

Psychological factors such as arousal level, pain tolerance, and motivation also affect performance (Tenenbaum et al., 2005). On the metabolic side, glycogen availability, hydration status, and micronutrient sufficiency influence both acute and chronic force production.

Technique and training specificity play a crucial role. Highly skilled lifters refine their motor patterns to improve bar path, reduce energy leaks, and maximise joint torque through optimal posture and rhythm.

Real-World Examples and Implications

• Weight classes in powerlifting and Olympic lifting provide clear examples. Lighter athletes often lift multiples of their body weight due to neural efficiency and mechanical advantages.

• A 70 kg Olympic lifter may clean and jerk over 180 kg, a feat requiring not just muscle, but near-perfect coordination, timing, and leverage.

Conclusion

While hypertrophy increases the potential for strength, it is neither the sole nor the dominant factor in many contexts. Neuromuscular coordination, tendon leverage, muscle architecture, and limb proportions all influence how much of that potential is realised.

To borrow from Newtonian mechanics: force output is the result of not just mass, but also acceleration and leverage. The human body is no different.

Key References

• Maughan, R. J., Watson, J. S., & Weir, J. (1983). Strength and cross-sectional area of human skeletal muscle. The Journal of Physiology, 338(1), 37–49.

• Moritani, T., & deVries, H. A. (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine, 58(3), 115–130.

• Kawakami, Y., Abe, T., Kuno, S. Y., & Fukunaga, T. (1995). Training-induced changes in muscle architecture and specific tension. European Journal of Applied Physiology, 72(1-2), 37–43.

• Sell, T. C., et al. (2007). Influence of physical characteristics on performance in the standing long jump. Journal of Strength and Conditioning Research, 21(2), 587–591.

• Tenenbaum, G., et al. (2005). Arousal and performance: The multidimensional approach. Handbook of Research in Sport Psychology, 3, 515–535.