Meeting Abstract

P3.62  Tuesday, Jan. 6  Variability of Walking in Humans QUITT, M.A.**; KANG, J.K.; DAVIDSON, B.C.; NGUYEN, C.T.; ADOLPH, S.C.; AHN, A.N.; Harvey Mudd College, Claremont Marissa_Quitt@hmc.edu

Almost all humans walk, but the morphology of their leg muscles and kinematics of their gait patterns differ visibly among individuals. In this study, we examine the relationship between the variability of gait patterns and neural control patterns with differences in body shape (i.e., muscle size) during walking in 19 young adults (mass = 60.9 +/- 6.9 kg; height = 1.67 +/- 0.09 m; average SD). We used ultrasonography to measure muscle morphology of the lateral gastrocnemius (LG), medial gastrocnemius (MG), and soleus (SOL) muscles at rest, and then recorded the muscle activity patterns (% maximum voluntary contraction, MVC) of these muscles and joint kinematics (Qualysis) during walking on a treadmill at 0.6 m/s. In 37% of the individuals (Group A), LG muscle activity levels were one-third to one-sixth that of the MG muscles, whereas the other subjects (Group B) showed roughly equal activity of the MG and LG muscles. Group A had shorter SOL muscles (t-test, p = 0.03), and tended to have smaller calf muscles in several other respects: LG thickness (p = 0.16), LG muscle length (p = 0.11), and LG muscle width (p = 0.18). Group A individuals were also slightly shorter in height (p = 0.04) with shorter lower legs (p = 0.11). There seemed to be no difference in pattern and amplitude of hip, knee, and ankle angles between the two groups. Individuals with slightly different morphometrics seemingly use different muscles to produce similar kinematic and mechanical output. The neuro-muscular input can vary, even though the mechanical output to produce walking is similar. This study was supported by a Barbara Stokes Dewey Endowment and HHMI.