Meeting Abstract
P3.49 Tuesday, Jan. 6 Modification of limb inertial properties leads to persistent changes in neural control of walking in humans OCOBOCK, Cara J*; PONTZER, Herman; MAKI, Julia; Washington University in St. Louis; Washington University in St. Louis; Washington University in St. Louis cjocoboc@artsci.wustl.edu
Animals with distally heavy limbs, such as primates and felids, have been proposed to use longer, slower strides to decrease leg-swing costs and minimize locomotor energy use. In this study, we investigated whether such cost-saving kinematic changes can be seen within a species when limb inertial properties are altered, and whether long-term changes in limb inertial properties produce persistent gait changes. Ten healthy human subjects walked and ran on a treadmill under both a Control condition, subjects wore a small weighted backpack, and a Leg Weights condition, subjects wore ankle weights. Kinematics and oxygen consumption were measured in both conditions; subjects then wore ankle weights for 6 hours, and oxygen use and kinematics were measured again. For walking trials, results from morning sessions indicated that subjects adapted immediately to a more distally located limb center of mass by using lower stride frequencies. Notably, results from afternoon walking sessions indicate that this change in gait persisted once ankle weights were removed and subjects returned to a normal, more proximally located limb center of mass. This persistence suggests a change in the neural control of rhythmic locomotor patterns brought about by experiencing a more distal hindlimb center of mass. There was no reduction in stride frequency while running in response to wearing ankle weights, suggesting that running is more resistant to kinematic adjustment. For all trials, locomotor cost was similar between Control and Leg Weights conditions. These results support the hypothesis that animals with distally heavy limbs can maintain low walking costs through kinematic adjustment, and suggest a feedback system in which locomotor control is influenced by limb inertial properties.
