LOWER-LIMB KINEMATICS DURING TREADMILL WALKING AFTER SPACE-FLIGHT - IMPLICATIONS FOR GAZE STABILIZATION

We examined the lower limb joint kinematics observed during pre- and p ostflight treadmill walking performed by seven subjects from three Spa ce Shuttle flights flown between March 1992 and February 1994. Basic t emporal characteristics of the gait patterns, such as stride time and duty cycle, showed no significant changes after flight. Evaluation of phaseplane variability across the gait cycle suggests that postflight treadmill walking is more variable than preflight, but the response th roughout the course of a cycle is joint dependent and, furthermore, th e changes are subject dependent. However, analysis of the phaseplane v ariability at the specific locomotor events of heel strike and toe off indicated statistically significant postflight increases in knee vari ability at the moment of heel strike and significantly higher postflig ht hip joint variability at the moment of toe off. Nevertheless, the o bservation of component-specific variability was not sufficient to cau se a change in the overall lower limb joint system stability, since th ere was no significant change in an index used to evaluate this at bot h toe off and heel strike. The implications of the observed lower limb kinematics for head and gaze control during locomotion are discussed in light of a hypothesized change in the energy attenuation capacity o f the musculoskeletal system in adapting to weightlessness.