Meeting Abstract

P3.196  Sunday, Jan. 6  Modeling the benefits and detriments of tendon elastic recoil RICHARDS, C.T.*; RIVERA, A.R.V.; CHOUDHURY, U.; Harvard University; Harvard University; Harvard University richards@fas.harvard.edu

Elastic energy stored in spring-like tendons is known to reduce locomotion cost or to enhance limb power output. Hence, many physiologists assume that elastic structures are beneficial. Yet, their implications are unknown across locomotor tasks. Using a simplified frog limb model, we examined whether a limb that is ‘well tuned’ for jumping also functions well during swimming (or, reciprocally, if a swimming-tuned limb enhances jumping). We characterized which intrinsic properties (muscle activation kinetics, Vmax, tendon stiffness) confer long distance jumping. We then determined whether those jumping ‘specializations’ enhance or impede swimming ability compared to a limb lacking a spring-like tendon. Two non-dimensional parameters were used: drag multiplier vs. mass multiplier representing drag loads during swimming versus inertial loads during jumping. Simulation data predicted that activation kinetics were nearly irrelevant for inertial loads, as long as full activation occurred within the first 20 ms. However, the shape of the activation waveform grew important as fluid drag increased, requiring an increasingly delayed onset of deactivation in order to maintain power output. Additionally, when drag multiplier/mass multiplier ratio was high (e.g. swimming with large webbed feet and compliant tendon) the tendon greatly attenuated muscle power transmission.