Meeting Abstract

P2.110  Saturday, Jan. 5  The unsteadiness of steady locomotion. SCHMIDT, A.*; BIKNEVICIUS, A. R.; Ohio University, Heritage College of Osteopathic Medicine; Ohio University, Heritage College of Osteopathic Medicine schmidta@ohio.edu

The crouched posture of small- to medium-sized mammals is considered to be advantageous for locomotion on substrates with irregularities where rapid adjustments in the degree of limb flexion and limb function are required. If highly flexible locomotor performance is a hallmark of small- to medium-sized quadrupeal mammals, then evidence of this flexibility may be evident in their locomotor behavior even on substrates without irregularities. To test this, we evaluated a suite kinematic and kinetic locomotor parameters for six rats (Rattus norvegicus) running at their maximum voluntary speed using two high-speed cameras placed lateral to a terrestrial substrate with two integrated force plates. Only trials in which the rats trotted for at least 2 consecutive and complete strides (i.e., four double-support phases) within a small speed range (± 10% of mean velocity) were analyzed. The results of this study show that rats adjusted locomotor speed frequently when running along the trackway, and transient shifts in ground reaction peak forces and impulses follow an irregular pattern. We conclude that this is evidence of a highly flexible locomotor system in rats and is suggestive that “steady-speed” and “steady-state” locomotion may be less relevant to small- to medium-sized mammals that customarily switch between accelerating and decelerating steps during their intermittent locomotion and as they cross uneven substrates.