Elastic recoil can either amplify or attenuate muscle-tendon power, depending on inertial vs. fluid dynamic loading

► We model a muscle-tendon to explore environment-morphology effects on power output. ► Models predict that power amplification occurs with both inertial and fluid loading. ► Elastic energy storage does not necessarily benefit locomotor performance. ► Inertial vs. fluid-dynamic loading governs the timing of elastic recoil.