While effective “biological springs” are present across species, large bipedal hoppers (i.e., kangaroos and wallabies) offer model examples of elastic energy storage and return mechanisms. For example, for these species, oxygen consumption during steady-state hopping does not increase linearly with speed as expected, but rather stabilizes as speed increases. Despite body design similarities, smaller bipedal hoppers, such as desert kangaroo rats, do not exhibit this energetic benefit. They are also thought to not benefit from analogous elastic energy storage due to comparatively thick tendons. However, recent material properties research reports a lower elastic modulus for the species’ ankle extensor tendons than originally assumed. These new elastic moduli values prompted our inquiry into how an increase in speed influences elastic energy recovery by kangaroo rats. For direct in-vivo measurements, a buckle force transducer was surgically attached to the ankle extensor tendons as animals (N = 3) hopped across a range of speeds (1.3 – 1.9 m/s). Increased speed resulted in increased tendon stress, rising from 2.69 MPa to 3.49 MPa, and increased energy storage, ranging from 0.88 mJ to 1.5 mJ. Based on estimated mechanical power requirements, results indicate energetic return is optimized at specific speeds, with percent energy savings increasing from 3.85% at 1.3 m/s to 5.19% at 1.7 m/s, but then falling to 4.38% at 1.9 m/s. Future analysis will include in-vivo strain assessments of individual ankle extensor muscles to better understand the patterns underlying labor division between muscle work production and elastic energy storage during hopping.