A Matter of Degrees: A Systematic Review of the Ergogenic Effect of Pre-Cooling in Highly Trained Athletes

Abstract

The current systematic review evaluated the effects of different pre-cooling techniques on sports performance in highly-trained athletes under high temperature conditions. PubMed/MEDLINE, EMBASE, Web of Science, CENTRAL, Scopus, and SPORTDiscus databases were searched from inception to December 2019. Studies performing pre-cooling interventions in non-acclimatized highly-trained athletes (>55 mL/kg/min of maximal oxygen consumption) under heat conditions (≥30 °C) were included. The searched reported 26 articles. Pre-cooling techniques can be external (exposure to ice water, cold packs, or cooling clothes), internal (intake of cold water or ice), or mixed. Cooling prior to exercise concluded increases in distance covered (1.5–13.1%), mean power output (0.9–6.9%), time to exhaustion (19–31.9%), work (0.1–8.5%), and mean peak torque (10.4–22.6%), as well as reductions in completion time (0.6–6.5%). Mixed strategies followed by cold water immersion seem to be the most effective techniques, being directly related with the duration of cooling and showing the major effects in prolonged exercise protocols. The present review showed that pre-cooling methods are an effective strategy to increase sports performance in hot environments. This improvement is associated with the body surface exposed and its sensibility, as well as the time of application, obtaining the best results in prolonged physical exercise protocols.

A Mixed-Method Approach of Pre-Cooling Enhances High-Intensity Running Performance in the Heat

“…When compared with non-cooling strategies, the use of internal pre-cooling strategies showed increase in time to exhaustion (19-31.9%) in highly trained athletes (>55 mL/kg/min of VO 2 max), while external cooling elicited increase in distance (3.6-13.1%) covered by highly trained athletes (Rodríguez et al, 2020). However, large volumes of fluid consumed before high-intensity exercise could result in a high risk of gastrointestinal upset or discomfort (Ross et al, 2011), which could lead to shivering and increase glycogen utilization (Jacobs et al, 1994).…”

“…Besides that, the stronger cooling power of pre-cooling protocol (exposure more part of body, longer period, and lower temperature) could induce muscle stiffness and uncomfortable sensations of coldness (Yeargin et al, 2006). Additionally, the mixed-method cooling (combination of internal and external strategies) vs. internal or external strategies did not exhibited any significant benefit, although a mixed-method approach showed a favourable trend to reduce thermal and improve performance in highly trained athletes (Rodríguez et al, 2020). To date, none of the studies on this topic have focussed on the effect of mixed-method cooling on the time to exhaustion under heat stress conditions in highly trained athletes (Aldous et al, 2019;Munoz et al, 2012;Ross et al, 2011).…”

Effects of hypohydration and fluid balance in athletes’ cognitive performance: a systematic review

“…As always, hypohydration can be expected in these events. The events include the Olympic Games: Beijing 2008; Rio 2016, Tokyo 2021; World Athletics Championships Doha 2019, and Federation International Football Association World Championships Qatar 2022 1 , 2 . With such exposure to hot environments, athletes mainly in prolonged vigorous exercise, racket and intermittent team sports experience significant and exceeding >2% body fluid loss due to thermoregulation 2 , 3 .…”

“…The events include the Olympic Games: Beijing 2008; Rio 2016, Tokyo 2021; World Athletics Championships Doha 2019, and Federation International Football Association World Championships Qatar 2022 1 , 2 . With such exposure to hot environments, athletes mainly in prolonged vigorous exercise, racket and intermittent team sports experience significant and exceeding >2% body fluid loss due to thermoregulation 2 , 3 . Inadequate and/or no fluid loss replacement can cause endurance capacity impairment associatd with physiological and cognitive function alterations 4 , 5 .…”

“…Despite that elite acclimated athletes may physiologically negotiate hyperthermic conditions, athletic trainers, sports scientists and sports medical staffs tirelessly work to uncover cooling techniques to curb core body temperature, delayed onset peripheral and central fatigue 4 , 23 – 26 . Thus, researchers have investigated dehydration, hypohydration and fluid ingestion aspects and their subsequent athletic performance effects 2 , 8 remains unclear. To date, no papers have reviewed and collectively discussed these aspects to equip professionals better understand impact on individual and team sport performances.…”