Meeting Abstract
P1.173 Monday, Jan. 4 Rapid Horizontal vs. Vertical Locomotion in the Mouse Lemur (Microcebus murinus) O’NEILL, M*; HANNA, J; Stony Brook University School of Medicine; West Virginia College of Osteopathic Medicine matthew.oneill@stonybrook.edu
Primates use both the ground and trees for traveling, feeding and escaping from predators. Their musculoskeletal systems must meet the competing demands for speed and economy on horizontal surfaces compared to the need for speed and power on vertical surfaces. Understanding how speed, economy and power are modulated during these different locomotor tasks provides insight into the limits of musculoskeletal function in primates and other mammals. Few data exist, however, that directly quantify how locomotor mechanics are altered during rapid horizontal vs. vertical locomotion. Video (250 Hz) and force data (2500 Hz) were collected from five adult mouse lemurs (Microcebus murinus) (Mb=0.062 kg) at the Duke Lemur Center, Durham, NC. Each lemur was encouraged to run at its fastest speed on a level horizontal runway and an instrumented 13 mm diameter vertical pole. Video data were used to determine speed, while forces were integrated to calculate whole-body center of mass (COM) work and power. M. murinus used bounding-galloping gaits on both substrates, with periods of foot-substrate contact separated by long (ground) or short (pole) aerial phases. The use of an aerial phase during rapid vertical climbing was unexpected, but is consistent with other forms of high-speed locomotion in primates (i.e., bipedal runs, gallops, ricochetal brachiation). Locomotor speeds were greater on horizontal than vertical surfaces, and this difference is significant (P < 0.05). COM work and power were also greater in vertical locomotion. Taken together, these data suggest that differential performance limits may exist for rapid horizontal and vertical locomotion. The implications of these data for estimates of whole-body energetic efficiencies will also be discussed. NSF BCS0749314.
