Introduction: The military population is at high-risk for injury with by painful sprains, especially of the ankle. The referenced treatment method for pain is the cryotherapy, consisting in applying cold-packs to the injured ankle several times a day. However, another pain treatment has been developed and is commonly used by high-level sports teams and rheumatologists but its efficacy has never been assessed within a military population, i.e. the hyperbaric CO2 cryotherapy, also called the neurocryostimulation.