When examining a subject in quiet stance from the side, the leg segment is usually seen to be oriented upwards and forwards by about 5°; the knee may be flexed by a few degrees, the shoulders are behind the great trochanter and the head is held forwards. The forward head position moves the center of gravity forwards and thus may increase pressure under the forefoot. Conversely, moving the head backwards should be accompanied by an increase in pressure under the heel and thus decreased pressure under the forefoot.

The study's objective is to study the influence of alignment of the head with the back (i.e. a rearward head position) and head rotation on the foot pressure distribution (measured using a foot pressure platform).

Inclusion Criteria:

• Age between 18 and 30
• Social security coverage
• Ability to understand the study's objectives, procedures and risks and to provide informed, written consent

Exclusion Criteria:

• Past or concomitant infectious or cancerous diseases of the spine
• Vertebral osteosynthesis
• Acute neck or arm pain
• Limb trauma in the previous 12 months
• Acute leg pain
• Neuropathic disease or the sequelae of neuropathic disease of the legs
• Myasthenia gravis
• Central nervous system disorders
• Inner ear problems
• Subjects under legal guardianship
• Known pregnancy
• Simultaneous participation in another biomedical research study of a drug or medical device.