Gait and balance disorders are important public health problem necessitating studies to try to prevent falls. Many studies have dealt with spatiotemporal gait parameters or balance during quiet standing (posturography). Nevertheless, falls occurred predominantly during gait, and rarely during quiet standing. We have developed a tool to measure balance during gait : the braking of the center of mass (CM), a biomechanical parameter obtained from the vertical velocity of the CM recorded with a force plate.

In previous studies, we have shown that the braking of the CM was a physiological and a active mechanism, reflecting balance during gait. Unfortunately, the braking of the CM measured on a force plate provide an important intra-individual variability.

The 3D optoelectronic gait analysis system (VICON) also provide an estimation of the CM. The primary goal of this study is to compare intra-individual variability of the braking of the CM determined by a force plate or the 3D optoelectronic gait analysis system (VICON) in healthy subjects.

Inclusion Criteria:

• Healthy subjects
• Between 20 and 40 years old
• Effective contraception for women of childbearing age

Exclusion Criteria:

• Neurological, vestibular, rheumatologic, orthopaedic disorders, which could influence gait and balance.
• Known spinal deformity
• Severe visual impairment : visual acuity less than 6/10
• Inability to stand and walk without assistance 15 meters
• Subjects without social security
• Subjects involved in another biomedical trial during this study
• Pregnant or breastfeeding women