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.

Effects of internal cooling on physical performance, physiological and perceptional parameters when exercising in the heat: A systematic review with meta-analyses

“…Our main finding of the present study was that internal cooling resulted in improvements in physical performance, which is in agreement with some (Bongers et al, 2015;Zhang, 2019;Rodríguez et al, 2020) but not all (Jones et al, 2012;Ruddock et al, 2017;Choo et al, 2018) systematic reviews on the topic. We overcame this apparent discrepancy in the literature by differentiating between time to exhaustion, typically used as a measure of aerobic capacity, and time trial performance, considered a more realistic and valid measure of performance (Saris et al, 2003).…”

Paper Selection Leads to a Misleading Conclusion: Updated Evidence of Ice Slurry Ingestion on Endurance Performance

“…To address the conclusion from Choo and colleagues' (2018) work, an updated meta-analysis has been performed excluding the four studies in question (Zhang, 2019) and reported a signifi cant eff ect size of ice slurry ingestion: Hedges' g, 0.60; 95% confi dence interval, 0.34-0.87. When this eff ect size is translated to performance eff ect, it represents 8.73% faster performance in the heat (Figure 1).…”

“…Ice slurry ingestion resulted in 8.73% (weighted mean, by a random-eff ects meta-analysis) performance enhancement. Data are replicated from Zhang (2019). For comparison, elite distance performance in the heat was slower (unweighted mean) in hot environments.…”

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“…Copernicus, Crossref, ROAD, in addition to "Google Scholar". Accordingly, the editorial team of this journal consists of scientists from Brazil, Turkey, Malaysia, Serbia, Croatia, Kosovo, Bosnia and Herzegovina, as well as the fact that this journal recognizes a growing number of eminent authors from the region, and the world [65,66,67,68,69,70,71,72,73,74,75] it is not surprising why it is recorded much larger citations compared to previous years, as well as to record the citations of this journal in the "Web of Science" database. Of course, it is expected that it will soon be indexed in one of the prestigious electronic citation databases.…”