The aim of study is to examine the combined effect of observation and imagination of gait on stride time variability of stride time among in healthy young and older adults.

JUSTIFICATION :

• In geriatric rehabilitation, gait reeducation, especially after a fall, is often encountered at the very beginning, to the inability to walk again. The main reasons are poorly controlled pain, immobilisations of a segment or the entire lower limb and adaptation to certain prostheses after fracture. This delay in walking recovery leads briefly to acute postural disadaptation that exposes to multiple decubitus complications such as infections, bedsores and muscular atrophy. Conventional rehabilitation techniques are then difficult to implement because they are poorly adapted to the geriatric patients.
• Today, many experimental data suggest a functional equivalence between making a movement, imagining and observing it. These data can be used to support the development of new rehabilitation techniques. For example, mental imagery is used in the learning of complex movements in order to improve motor performance.
• Stride variability, and more specifically stride time variability was identified as the best marker of the automatic walking, a low variability corresponding to an automatic and safety gait.
• We hypothesize that the combined effect of observation and imagination of a gait using an imposed cadency cadency may reduce stride time variability of stride time in healthy young and older adults.

The secondary objectives of the study are as follows:

• To examine the combined effect of observation and imagination of a gait on mean value of spatio-temporal parameters in healthy young and older adults.
• To study the influence of age on the combined effect of observation and imagination of gait on mean value and coefficient of variation of spatio-temporal parameters in healthy young and older adults

Inclusion Criteria:

• Age ≥ 20 years
• Able to walk without walking aid on 15 metres
• Written informed consent to participate in the study (or trustworthy person)
• Being affiliated to a social security regime

Exclusion Criteria:

• Osteoarticular pathologies of the lower limbs and / or spine altering the biomechanical characteristics of the body members.
• Ataxia
• History and / or progressive neuropsychiatric disorders.
• Score in the 4-items Geriatric Depression Scale > 1.
• Enrolment in another simultaneous clinical trial (Participation in a concomitant clinical trial.)
• Civil defense measures underway (Measures civil protection type trusteeship / guardianship / safeguarding justice in progress.)
• Refusal to participate