Optimizing Ice Slurry Ingestion for Endurance Performance in the Heat: A Meta-Analysis

Abstract

Ice slurry ingestion is a simple cooling intervention purported to improve endurance performance. Despite its popularity in the fi eld, a recent meta-analysis suggested this intervention has no performance eff ect. The aim of the present meta-analysis was to determine the eff ect of ice slurry ingestion on endurance performance in the heat. Data for this meta-analysis were retrieved from the PubMed. Eff ect sizes were calculated as the standardized mean diff erence (Hedges’ g), and meta-analyses were completed using a random-eff ects model. A method-of-moments meta-regression was used to determined confounding factors. Sixteen studies using randomized controlled trials with a total of 152 subjects were included. Improvement in endurance performance in the heat was moderate: g=0.54 (95% confi dence interval, 0.30-0.77, p<0.001). There was a signifi cant dose eff ect associated with the endurance performance (p=0.024); moreover, the performance eff ects of ice slurry ingestion were not infl uenced by the timing of ingestion or environmental conditions. These data support the ingestion of ice slurry during endurance events in the heat. To optimize this simple cooling strategy in the fi eld, it is recommended to ingest no more than 10 g • kg−1 before or during exercise.

Keywords

• Cooling
• Thermoregulation
• Time to Exhaustion
• Systemic Review