This study evaluates the effect of a single high-velocity low-amplitude spinal manipulation on both cardiovascular autonomic activity and pressure pain thresholds.

It is a cross-over study, thus each participant will undergo both interventions (spinal manipulation and sham manipulation). Both interventions will be separated by a 48 h wash-out period.

Several systematic reviews have shown that spinal manipulations may have an immediate effect on autonomic nervous system activity (e.g. increase in skin sympathetic nerve activity) and on sensitivity to experimentally-induced pain (e.g. increase in pressure pain threshold).

It is generally unknown i) if these supposed effects last after the immediate post intervention period and ii) if there is a statistical relationship between them, considering that pain and autonomic networks are closely connected and interact at the peripheral, spinal and supra-spinal levels.

The primary aim of the study is to assess every single effect immediatly and at short-term after the intervention.

The secondary aim is to assess the bivariate statistical relationship between cardiovascular autonomic activity and sensitivity to experimentally-induced pain after the intervention.

Cardiovascular autonomic nervous system activity is assessed with both heart rate and systolic blood variabilities

Sensitivity to experimentally-induced pain is measured using pressure pain threshold.

Inclusion Criteria:

• First-year chiropractic student at IFEC
• Volunteer
• Healthy (no pain, no disease)

Exclusion Criteria:

• Counter indications to spinal manipulation
• Drugs intakes (pain killers or beta-blockers)
• Food, Caffeine and tobacco intakes during the previous hour
• Alcohol intake and performance of strenuous physical activity the day of the experimentation