By Joene Hendry

NEW YORK (Reuters Health) - The most effective way to lower the core body temperature of a person with exercise-induced heat exhaustion or heat stroke is to immerse the body in ice-cold water, according to a review of published research on the topic.

When cold-water immersion is not immediately possible, alternative cooling methods must be immediately implemented while awaiting emergency transport to a medical facility, reports Brendon P. McDermott, a doctoral research fellow and instructor at the University of Connecticut in Storrs, and colleagues.

An acceptable alternative, McDermott's team reports in the Journal of Athletic Training, is the combination of cold-water dousing, for example from a garden hose or large containers of ice-water, constant fanning, and continuously covering the body with cold, wet towels.

However, "applying ice bags to major arteries -- a practice still taught among some health care professionals -- is not an appropriate treatment and does not efficiently cool the body," McDermott told Reuters Health.

Physical exertion in warm or hot environments can lead to hyperthermia. The initial stage, referred to as heat exhaustion, is characterized by an increase in body temperature, dehydration, nausea and dizziness.

This may progress to heat stroke, a potentially life-threatening condition in which the body can no longer regulate its temperature. Symptoms include dangerously high body temperature (104 F), hot dry skin, rapid heartbeat and breathing, and high or low blood pressure.

To determine the most effective treatments for this condition, the investigators evaluated existing research on whole-body cooling methods for hyperthermia induced by physical activity.

The investigators identified seven studies that assessed cooling methods such as partial or whole-body immersion in cold- or ice-water, the application of wet towels and fanning, cold water splashing and fanning, the application of ice packs to specific areas of the body, or sitting in the shade.

Of these methods, the investigators found ice-water immersion in water circulated to maintain a cold temperature "the superior whole-body cooling treatment for exercise-induced hyperthermia."

McDermott's team concludes that cold-water and ice-water immersion, as recommended for exertional heat stroke by the National Athletic Trainers' Association and the American College of Sports Medicine, remain the body-cooling methods with the fastest cooling times.

SOURCE: Journal of Athletic Training, February 2009.

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