title: A 3D analysis of hindlimb motion during treadmill locomotion in rats after a 14-day episode of simulated microgravity.
abstract: This study describes the effect of simulated microgravity in rat on kinematics and electromyographic activity during treadmill locomotion. The analysis was performed in rats submitted to 14 days of hindlimb unloading (HU), in rats submitted to hindlimb unloading and then authorized to recover for 7 days (REC), and in aged-matched control rats (CON). Movements of the right hindlimb were measured with a 3D-optical analyzer (SAGA3 system) and five small infrared-reflective disks positioned on the skin, recorded by three CCD cameras. Results showed that HU rats exhibited hyperextensions at the end of the stance phase. By contrast, during the major part of the step, the ankle was less extended than CON. Possible origins of the changes are discussed. This leads to the question of how important is sensory input in the regulation of the locomotor pattern after HU. Data obtained in REC animals showed that 1 week of recovery allowed the restoration of a good locomotor performance. However, the limb motion remained abnormal, and at contrary to HU rats: higher extension during the step, except at push-off when the limb was in hyperflexion. We concluded that simulated microgravity involves a dual adaptive process: a first one during unloading, and a second one during the period of recovery, which is not a simple return to initial characteristics of the locomotor pattern.
authors.affiliation: Laboratoire de Plasticité Neuromusculaire, Université des Sciences et Technologies de Lille, UPRES-EA 1032, IFR 118, 59655 Villeneuve d'Ascq cedex, France. canu@univ-lille1.fr
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Canu
authors.forename: Cyril
authors.initials: C
authors.lastname: Garnier
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Lepoutre
authors.forename: Maurice
authors.initials: M
authors.lastname: Falempin
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D004576:Electromyography; D005684:Gait / Q000502:physiology*; D006614:Hindlimb / Q000502:physiology; D019417:Hindlimb Suspension / Q000502:physiology*; D021621:Imaging, Three-Dimensional; D008124:Locomotion / Q000502:physiology*; D008297:Male; D016555:Matched-Pair Analysis; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018474:Weightlessness Simulation / Q000379:methods