Research article - (2021)20, 26 - 34
DOI: https://doi.org/10.52082/jssm.2021.26
A Mixed-Method Approach of Pre-Cooling Enhances High-Intensity Running Performance in the Heat
Minxiao Xu1,2, Zhaozhao Wu2,6, Yanan Dong4, Chaoyi Qu2,3, Yaoduo Xu7, Fei Qin2,5, Zhongwei Wang1,2, George P. Nassis8,9, Jiexiu Zhao2,
1School of Kinesiology, Shanghai University of Sports, Shanghai, China
2Exercise Biological Center, China Institute of Sport Science, Beijing, China
3School of Sport Science, Beijing Sport University, Beijing, China
4Beijing Institute of Sport Science, Beijing, China
5School of Physical Education, Jinan University, Guangzhou, China
6Physical Education Department, Northwest University, Xi’an, China
7Physical Education Department, Northwestern Poly-technical University, Xi’an, China
8Physical Education Department-(CEDU), United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates
9Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster), University of Southern Denmark, Odense, Denmark

Jiexiu Zhao
✉ China Institute of Sport Science, No.11, Tiyuguan Road, Dongcheng District, Beijing, China
Email: zhaojiexiu@ciss.cn
Received: 09-06-2020 -- Accepted: 01-12-2020
Published (online): 01-03-2021
ABSTRACT

We investigated whether single or combined methods of pre-cooling could affect high-intensity exercise performance in a hot environment. Seven male athletes were subjected to four experimental conditions for 30 min in a randomised order. The four experimental conditions were: 1) wearing a vest cooled to a temperature of 4 ™ƒ (Vest), 2) consuming a beverage cooled to a temperature of 4 ™ƒ (Beverage), 3) simultaneous usage of vest and consumption of beverage (Mix), and 4) the control trial without pre-cooling (CON). Following those experimental conditions, they exercised at a speed of 80% VO2max until exhaustion in the heat (38.1 ± 0.6 ™ƒ, 55.3 ± 0.3% RH). Heart rate (HR), rectal temperature (Tcore), skin temperature (Tskin), sweat loss (SL), urine specific gravity (USG), levels of sodium (Na+) and potassium (K+), rating of perceived exertion (RPE), thermal sensation (TS), and levels of blood lactic acid ([Bla]) were monitored. Performance was improved using the mixed pre-cooling strategy (648.43 ± 77.53 s, p = 0.016) compared to CON (509.14 ± 54.57 s). Tcore after pre-cooling was not different (Mix: 37.01 ± 0.27 ™ƒ, Vest: 37.19 ± 0.33 ™ƒ, Beverage: 37.03 ± 0.35 ™ƒ) in all cooling conditions compared to those of CON (37.31 ±0.29 ™ƒ). A similar Tcore values was achieved at exhaustion in all trials (from 38.10 ™ƒ to 39.00 ™ƒ). No difference in the level of USG was observed between the conditions. Our findings suggest that pre-cooling with a combination of cold vest usage and cold fluid intake can improve performance in the heat.
Key words: Cooling prior to exercise, external and internal cooling, hyperthermia, thermoregulation, high-intensity aerobic exercise

Key Points
  • Precooling strategies with 30 min independent or simultaneous precooling maneuvers could improve running performance of 80% VO2max in hot and humid climatic conditions compared with the control condition.
  • Wearing a 4™ƒ vest might augment the capacity of heat dissipation by decreasing Tskin.
  • Ingesting a 4™ƒ beverage might increase the capacity of heat storage and maintain homeostasis by reducing Tcore, HR and [Bla].
  • The mix method-precooling maneuver seems to be more effective than others by maintaining core-to-skin thermal gradient and fortifying heat storage to relieve thermophysiological strain.








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A Mixed-Method Approach of Pre-Cooling Enhances High-Intensity Running Performance in the Heat
Minxiao Xu, Zhaozhao Wu, Yanan Dong, Chaoyi Qu, Yaoduo Xu, Fei Qin, Zhongwei Wang, George P. Nassis, Jiexiu Zhao
2021(20), 26 - 34.
DOI: https://doi.org/10.52082/jssm.2021.26