Experimental: Spinal manipulation

Spinal manipulative therapy will be delivered to the cervical spine (segments including occiput-atlas to C7-D1) according to the chiropractors' evaluation during each visit. During each session, one or two segments will be manipulated using a high-velocity low-amplitude thrust manipulation (a joint cavitation will be expected, if not, the thrust can repeated once) applied to the segments with the highest motion restriction, as determined by the chiropractor by static and motion palpation of the cervical spine.

Placebo_comparator: Placebo

Sham manipulation will be delivered to the cervical spine (segments including occiput-atlas to C7-D1) according to the chiropractors' evaluation during each visit. During each session, one or two segments will receive a sham manipulation applied to the segments with the highest motion restriction, as determined by the chiropractor by static and motion palpation of the cervical spine. The sham manipulation will consist in a identical contact to the real manipulation, except the thrust will be delivered towards the table, away from the target segment and with the intention to lower the cervical drop piece of the table, which will substitute the joint cavitation noise.