Human Locomotion under Reduced Gravity Conditions: Biomechanical and Neurophysiological Considerations (original) (raw)
Related papers
Changes of Gait Kinematics in Different Simulators of Reduced Gravity
Journal of Motor Behavior, 2013
Gravity reduction affects the energetics and natural speed of walking and running. But, it is less clear how segmental coordination is altered. Various devices have been developed in the past to study locomotion in simulated reduced gravity. However, most of these devices unload only the body center of mass. Here, we reduced the effective gravity acting on the stance and/or swing leg to 0.16g using different simulators. Locomotion under these conditions was associated with a reduction in the foot velocity and significant changes in angular motion. Moreover, when simulated reduced gravity directly affected the swing limb, it resulted in significantly slower swing and longer foot excursions, suggesting an important role of the swing phase dynamics in shaping locomotor patterns.
Human Locomotion in Hypogravity: From Basic Research to Clinical Applications
Frontiers in physiology, 2017
We have considerable knowledge about the mechanisms underlying compensation of Earth gravity during locomotion, a knowledge obtained from physiological, biomechanical, modeling, developmental, comparative, and paleoanthropological studies. By contrast, we know much less about locomotion and movement in general under sustained hypogravity. This lack of information poses a serious problem for human space exploration. In a near future humans will walk again on the Moon and for the first time on Mars. It would be important to predict how they will move around, since we know that locomotion and mobility in general may be jeopardized in hypogravity, especially when landing after a prolonged weightlessness of the space flight. The combination of muscle weakness, of wearing a cumbersome spacesuit, and of maladaptive patterns of locomotion in hypogravity significantly increase the risk of falls and injuries. Much of what we currently know about locomotion in hypogravity derives from the vide...
2002
Many neurophysiological and behavioural studies suggested that the lower limb endpoint might be a centrally represented variable within the gravity reference frame and effectively controlled during the locomotion. This investigation examines the effects of prolonged exposure to microgravity upon lower limb endpoint kinematics. Seven cosmonauts were tested before and the 2nd day after a 6 month orbital mission. The spatio-temporal patterns of the limb extremity (malleolus) were analysed during the swing phase of the walk using a motion analysis system. Paths and velocity profiles of endpoint displacements were computed and compared for both the pre-and post-flight walking sessions. The results indicated significant modifications in both spatial and temporal features the 2nd day after re-entry on Earth. The step was significantly lengthened, and its shape was altered, presenting higher vertical component compared with the pre-flight values. The acceleration duration was increased whereas the swing duration remained invariant whatever the walking session. These modifications in endpoint kinematics could partly but not completely be explained by peripheral factors like muscle atrophy or plasticity at the spinal level. We suggest that, apart of changes in peripheral level, central modifications concerning internal models of gravity, putatively used to plan limb motion, might have induced such locomotor changes.
MOON GAIT: INVESTIGATING WALK PATTERNS IN REDUCED GRAVITY
During the Apollo missions, it has been discovered that people on the Moon have a completely different way of moving and walking. Currently the DLR (German Aerospace Center) is running a study to investigate human-machine system interaction in hypogravity in order to design interfaces that will support the user in these extreme conditions. This paper is a summary review of a thesis " Moon Gait: Investigating a methodology for analysis of hypogravity gait posture for architecture design in space " (Mukadam, 2017) based mainly on OAE, and also presents results from the first pilot study on the differences of vertical oscillation in hypogravity (Mukadam, et al., 2017). In particular, videos of a first group of 6 participants have been analysed that were moving at two different speeds (11.5 & 4 Km/h) and two kinds of hypogravity (0.6 and 0.3g) on a vertical treadmill. On this vertical treadmill developed by Prof. Jörn Rittweger (head of the 'Space Physiology' division at the DLR institute), the subject is able to walk vertically. In this position, gravity no longer has any influence on the subject's vertical axis and hypogravity can be reproduced using a special type of software that calculates the tightness of the string where the subject is belted. The methodology included video analysis via Tracker software measuring the changing of the vertical oscillation (variation in the height given by the oscillation of the top of the head while walking) and OAE. The results of the pilot study has been used to formulate the hypothesis also applicable to Moon hypogravity. This pilot experiment with weight reduction using vertical treadmill, confirmed that the walking altitude between the two different speeds is normally different on Earth, and brought about the hypothesis that there is a homogenization of the vertical oscillation on the gait at slow and fast speeds that is not present in the normal behavioural pattern on Earth. This work motivates the need for collaboration between different fields such as physiological research and human-machine interaction in order to realize successful space exploration.
Modelling the neuromechanical events of locomotion at varying gravitational levels
Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, 2000
The purpose of the present study was to determine the feasibility of using a neuromechanical model of human locomotion based on a model previously published by Taga et al. to simulate gait at various speeds and gravitational levels. The results indicate that this model may be appropriate for studying walking at 1 G but not for higher speed or lower G locomotion.
Experimental Brain Research, 2004
Recovery of locomotor function was investigated in seven cosmonauts exposed to microgravity for 6 months. Crew members executed a locomotor task with visual cues (eyes open, EO) and without them (eyes closed, EC). The locomotor task consisted of ascending a two-step staircase, jumping down from a 30-cm high platform, and finally walking 4 m in the straight-ahead direction. Subjects were tested before the flight (D-30), and on the second day (R+2) and the sixth day (R+6) after the flight. Cosmonauts succeeded in all locomotor subtasks as early as R+2. In particular, microgravity exposure did not prevent cosmonauts from producing a straight walking trajectory even when blindfolded (deviation at R +2 with EO 2.0±0.7°, and with EC 4.7±1.9°). However, lateral movements of trunk were found to be increased at R+2 (16%), suggesting post-flight gait instability. Modifications of the timing of forward trunk movements were also detected at R+2. Unexpectedly, coordination patterns between head and trunk movements remained unchanged. The maximum amplitude of head pitches was 5°or less. Yet, the cosmonauts held their heads at lower positions at R+2 in comparison with their pre-flight postures, and they lowered their heads even further during blindfolded locomotion. In general, comparable spatial and temporal modifications of head and trunk movements at R+2 were observed during the stair and gait cycles. Mean values of locomotor descriptors measured at R+6 did not deviate from the pre-flight baseline. When performing jumps after the return from their flight, cosmonauts decreased the amplitude and speed of head rotation by approximately 50% in comparison with the pre-flight values. In addition, the timing of head pitches was uncertain after weightlessness. All the above changes endured at R+6. Previous studies reported that prolonged exposure to microgravity adversely affects the motor performance in the initial hours upon re-entry to Earth. However, gait analysis revealed that cosmonauts recovered near-optimal locomotor abilities as early as the second day post-flight. Results suggest a notable capability of the central nervous system to rapidly accommodate to changing physical environment and body properties. The role of head stabilization at a lower position is conjectured to be an adaptive response to microgravity-induced motor disorders.
Journal of Biomechanics, 2005
This study deals with the quantitative assessment of exchanged forces and torques at the restraint point during whole body posture perturbation movements in long-term microgravity. The work was based on the results of a previous study focused on trunk bending protocol, which suggested that the minimization of the torques exchanged at the restraint point could be a strategy for movement planning in microgravity (J. Biomech. 36(11) (2003) 1691). Torques minimization would lead to the optimization of muscles activity, to the minimization of energy expenditure and, ultimately, to higher movement control capabilities. Here, we focus on leg lateral abduction from anchored stance. The analysis was based on inverse dynamic modelling, leading to the estimation of the total angular momentum at the supporting ankle joint. Results agree with those obtained for trunk bending movements and point out a consistent minimization of the torques exchanged at the restraint point in weightlessness. Given the kinematic features of the examined motor task, this strategy was interpreted as a way to master the rotational dynamic effects on the frontal plane produced by leg lateral abduction. This postural stabilizing effects was the result of a multi-segmental compensation strategy, consisting of the counter rotation of the supporting limb and trunk accompanying the leg raising. The observed consistency of movement-posture co-ordination patterns among lateral leg raising and trunk bending is put forward as a novel interpretative issue of the adaptation mechanisms of the motor system to sustained microgravity, especially if one considers the completely different kinematics of the centre of mass, which was observed in weightlessness for these two motor tasks.