Meeting Abstract

58.4  Tuesday, Jan. 5  Plantarflexor moment arm correlates with walking speed in mobility-limited older adults LEE, Sabrina/SM*; TOM, Novak; PIAZZA, Stephen/J; The Pennsylvania State University; The Pennsylvania State University; The Pennsylvania State University sabrina_lee_4@sfu.ca

Classical research in comparative functional morphology suggests that the skeletal structure and muscle architecture of many animals are well adapted to their locomotor behaviors. The influence of variation of musculoskeletal structure on locomotor function is not as well established for human movements, especially in older adults. Decreases in plantarflexor strength and power have been found to correspond to reduced gait speed in older adults, but all the determinants of reduced strength and power are not well characterized. In the present study, we used ultrasound imaging to quantify musculoskeletal architectural parameters of the lateral gastrocnemius (fascicle length, pennation angle, muscle belly thickness, and plantarflexion moment arm) in healthy elderly men for whom gait speed was also measured. Moment arm was found to be a strong predictor of preferred gait velocity during a 6-minute walk in the slowest elderly subjects after subjects were separated post-hoc into n=10 slow (1.06 to 1.38 m/s) and fast (1.44 to 1.64 m/s) groups. For the slow group, there was a significant relationship between preferred gait velocity and moment arm (R2 = 0.669, p = 0.004) but for the fast group, there were no significant relationships between preferred gait velocity and any musculoskeletal architectural parameters. Nor were any significant relationships found between maximal gait speed over a 4 m course and any musculoskeletal parameter, even when subjects were separated by speed. These results suggest that moment arm is determinative of gait speed among mobility-limited older adults, perhaps because of the constraints of age-related sarcopenia upon muscle adaptation.