The storage and release of elastic strain energy can sidestep the force-velocity constraints of muscle. While energy stored in a muscle tendon unit depends on relative muscle and spring properties, we do not know whether muscle-tendon units (MTU) systematically adapt to functional demand. To test whether jumping during maturation alters adult MTU properties, we restricted jumping in a group of guinea fowl (Numida Meleagris, n=8) during growth. At maturity, we compared the jump performance of our treatment group to controls (n=8) and measured the morphological characteristics of the muscle, tendon and lever system of the gastrocnemius MTU. We found restricted birds jumped with lower takeoff velocities, yet there were no significant differences in the components of the elastic system between groups. Further, we quantified the energy storage capacity by measuring tendon potential energy when simulating 100% activation of the gastrocnemius muscle of a flock of subject-specific musculoskeletal models that integrated individuals’ morphological measurements. We found no difference in energy storage capacity between groups or any correlation with experimentally measured jump performance. We conclude that gastrocnemius elastic system in the guinea fowl displays little to no plastic response to decreased demand during growth and that neural control of elastic systems may constrain performance more than morphology.