Effects of Intravenous Cold Saline on Hyperthermic Athletes Representative of Large Football Players and Small Endurance Runners.

OBJECTIVE

To evaluate the cooling effects of intravenous (IV) cold normal (0.9%) saline on hyperthermic athletes.

DESIGN

Randomized crossover study design.

SETTING

Controlled research laboratory.

PARTICIPANTS

Twelve male participants who were representative of a collegiate cross-country (6) and American football (6) population.

INTERVENTIONS: Participants underwent body composition analysis using a BodPod. They were placed in an environmentally controlled chamber and brought to a Tc of 39.5°C with dynamic exercise. When temperatures were reached, they were treated with either 2 L of cold saline (CS) (4°C) or intravenous room temperature (22°C) saline (RS) over a ∼30-minute period. Tre was measured with a rectal temperature probe every minute during the treatment period.

MAIN OUTCOME MEASURES: Total ΔTre (ending Tre - starting Tre) and cooling rate (total change in Tre/time) were measured for each condition, and body composition variables calculated included body surface area (BSA), BSA-to-mass ratio (BSA/mass), lean body mass, and body fat percentage (%BF) (P < 0.05).

RESULTS

Statistically significant differences were found in the total ΔTre and cooling rate between the CS and RS trials. The cooling rate for the CS trials was significantly correlated to mass, BSA, BSA/mass, and %BF.

CONCLUSIONS

In hyperthermic athletes, core temperature was reduced more effectively using chilled saline during IV infusion. Body composition had a significant impact on overall cooling revealing that the smaller and leaner participants cooled at a greater rate. When indicated, CS infusion could be considered for cooling hyperthermic individuals when other methods are not available.