title: Gait transitions in simulated reduced gravity.
abstract: Gravity has a strong effect on gait and the speed of gait transitions. A gait has been defined as a pattern of locomotion that changes discontinuously at the transition to another gait. On Earth, during gradual speed changes, humans exhibit a sudden discontinuous switch from walking to running at a specific speed. To study the effects of altered gravity on both the stance and swing legs, we developed a novel unloading exoskeleton that allows a person to step in simulated reduced gravity by tilting the body relative to the vertical. Using different simulation techniques, we confirmed that at lower gravity levels the transition speed is slower (in accordance with the previously reported Froude number ∼0.5). Surprisingly, however, we found that at lower levels of simulated gravity the transition between walking and running was generally gradual, without any noticeable abrupt change in gait parameters. This was associated with a significant prolongation of the swing phase, whose duration became virtually equal to that of stance in the vicinity of the walk-run transition speed, and with a gradual shift from inverted-pendulum gait (walking) to bouncing gait (running).
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 306 via Ardeatina, 00179 Rome, Italy. y.ivanenko@hsantalucia.it
authors.forename: Yuri P
authors.initials: YP
authors.lastname: Ivanenko
authors.forename: Francesca Sylos
authors.initials: FS
authors.lastname: Labini
authors.forename: Germana
authors.initials: G
authors.lastname: Cappellini
authors.forename: Velio
authors.initials: V
authors.lastname: Macellari
authors.forename: Joseph
authors.initials: J
authors.lastname: McIntyre
authors.forename: Francesco
authors.initials: F
authors.lastname: Lacquaniti
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D018472:Hypogravity; D008124:Locomotion / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*