The Two-Spring Model System and the Magic of “Spring Action” in Elite Athletes


The world of athletic performance is one of the most fascinating and complex aspects of human biomechanics. As athletes constantly strive to enhance their capabilities, two vital concepts emerge at the forefront: the two-spring model system and the “spring action.” Both highlight the significance of training muscles and tendons and the biomechanical marvels inherent in the human body.

Understanding the Two-Spring Model System

This system revolves around the coordinated effort between muscles and tendons. By efficiently training these two interconnected systems, athletes can achieve an impressive free energy return and improved overall performance. This synergy, when optimized, allows athletes to execute powerful movements covering vast distances with each repetition, as exemplified by the incredible technique of a 3-time female Olympian in video below.

The Magic of the “Spring Action”

While the two-spring model system focuses on the relationship between muscles and tendons, the “spring action” emphasizes the biomechanics of enhanced movement. This mechanism, governed by the psoas muscle and a network of tendons and ligaments, provides athletes with a unique edge in speed and efficiency. It’s like comparing a short punch to a long-winded swing—the latter packs a more substantial force due to the space allowing for acceleration.

Sprinters, such as the iconic Usain Bolt, demonstrate the potency of this mechanism. Despite physical attributes that might seem disadvantageous, Bolt’s technique, harnessing the spring action, allows him to outpace competitors with ease.

Training Processes: Merging Both Worlds

Training for both the two-spring system and the spring action requires a precise methodology. Achieving the optimal stiffness in muscles and tendons, while harnessing the body’s natural springing mechanism, poses challenges but yields significant rewards. For instance, while weighted sleds can enhance the springing action, they must be used correctly to avoid hindering performance.

Flaws and Considerations

Athletes should be wary of overemphasizing one training aspect at the expense of another. Solely focusing on speed training can lead to muscle neglect, while an exclusive emphasis on heavy strength training might strain tendons. Thus, a holistic approach, incorporating both the two-spring system and the spring action, is paramount for optimal performance and injury prevention.


The realms of the two-spring model system and the “spring action” offer athletes and coaches profound insights into optimizing performance. Harnessing these biomechanical marvels allows athletes to achieve unparalleled feats, a testament to the human body’s extraordinary capabilities. As our understanding deepens and training methodologies evolve, athletes will continue to break barriers, setting new benchmarks in their respective sports.

Elite Coach Chris Korfist Lecturing about the The Spring System in Sport and Sprinting

Cal Dietz Lecturing below on the Two Spring System and training it.

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