Extremity cooling for heat stress mitigation in military and occupational settings

• Numerous work settings may cause heat stress that increases injury risk.
• Extremity cooling in cold water can accelerate body cooling from 0.4 to 1.0 °C/10 min.
• Immersing the hands and forearms is preferable to just the hands or the feet only.
• Arm immersion can reduce cardiovascular strain.
• The Arm Immersion Cooling System provides cooling in the field training environment.

Physical work, high ambient temperature and wearing protective clothing can elevate body temperature and cardiovascular strain sufficiently to degrade performance and induce heat-related illnesses. We have recently developed an Arm Immersion Cooling System (AICS) for use in military training environments and this paper will review literature supporting such an approach and provide details regarding its construction. Extremity cooling in cool or cold water can accelerate body (core temperature) cooling from 0.2 to 1.0 °C/10 min vs. control conditions, depending on the size/surface area of the extremity immersed. Arm immersion up to the elbow results in greater heat loss than hand- or foot-only immersion and may reduce cardiovascular strain by lowering heart rate by 10–25 beats/min and increase work tolerance time by up to 60%. The findings from studies in this paper support the use of AICS prototypes, which have been incorporated as part of the heat stress mitigation procedures employed in US Army Ranger Training and may have great application for sports and occupational use.