The physiological impact of body armor cooling devices in hot environments: a systematic review.

BACKGROUND Heat-related illness is a primary threat to unit readiness, and individual body armor (IBA) cooling devices represent one potential solution. PURPOSE To quantify research findings of active and passive cooling devices designed to reduce physiological strain while wearing IBA during strenuous tasks using a systematic review approach. METHODS Literature searches were performed in multiple databases using the key words "physiological," "body armor," "military," "cooling," and "thermal." Two independent reviewers appraised methodological quality using a modified Downs and Black Quality Index. Physiological outcomes were tabulated and effect sizes were calculated when appropriate. RESULTS The search yielded 733 citations, with nine articles fitting our inclusion criteria: six articles with active and three articles with passive cooling devices. Results reveal a moderate level of methodological quality. On average, all six active IBA cooling device studies compared to controls (IBA only) reported decreases in one or more measures of physiological strain-core and skin temperature, heart rate. Conversely, passive cooling device effects were negligible. CONCLUSION Active cooling devices may decrease the physiological strain associated with wearing IBA in hot environments. Further development of optimal cooling strategies to reduce physiological strain during operations where IBA is required is warranted.