Muscle-tendon mechanics resolve the trade-off between energy-efficient and robust locomotion.

Animals utilize elastic tendons in their limbs to store and release energy, reducing muscle effort and overall energy expenditure. At the same time, they navigate rough terrain dynamically without falling, despite significant neural delays. This ability allows them to achieve both robust and energy-efficient locomotion simultaneously-two properties often considered trade-offs in robotics. Through computational simulations, this study demonstrates how muscle-tendon mechanics can facilitate both energy-efficient and robust locomotion during perturbed vertical hopping across different muscle-tendon length configurations. Integrating muscle-tendon-like viscoelastic materials into legged robots may offer a solution to the previously perceived trade-off.