Meeting Abstract

P3.165  Sunday, Jan. 6  Making a Splash: The effect of environment on landing preparation in Lithobates catesbeiana KATZ, H*; LEVIN, E; MACESIC EKSTROM, LJ; GILLIS, GB; Univ. of Chicago; Tufts University; Wheaton College; Mount Holyoke College ggillis@mtholyoke.edu

During a step or a jump, limb muscles are activated before the foot actually makes ground contact to help coordinate landing and counteract ground reaction forces. In humans and a number of other mammals, both the timing and amplitude of this “pre-landing” muscle activity are variable and shift with the expected time and force of impact. Recent work with various anuran species, including the American bullfrog (Lithobates catesbeiana), has shown that they too produce pre-landing muscle activity in the forelimbs that is tuned to the time and magnitude of impact. In order to test if this pre-landing muscle activity is conserved regardless of landing environment we took electromyographic recordings from the m. coracoradialis (an elbow flexor) and the lateral head of m. anconeus (an elbow extensor) during jumps into water as well as onto land. Results indicate that similar patterns of activity are present in these muscles regardless of the landing medium. However, in some animals pre-landing muscle activation intensity in the m. anconeus was lower when the animal was hopping into water than when it was hopping onto land. Further, pre-landing intensities in the m. coracoradialis were positively correlated with distance during both types of hop, although they increased at a greater rate with hop distance when animals were landing in water compared to on land. Our data suggest that pre-landing forelimb muscle activity in bullfrogs can be subtly modulated depending on the landing environment.