Effects of warm-up and precooling on endurance performance in the heat

Institute of Sports Science, University of Dortmund, Otto-Hahn-Str 3, 44227 Dortmund, Germany.
British Journal of Sports Medicine (Impact Factor: 5.03). 07/2007; 41(6):380-4. DOI: 10.1136/bjsm.2006.032292
Source: PubMed


To examine the effects of different thermoregulatory preparation procedures (warm-up (WU), precooling (PC), control (C)) on endurance performance in the heat.
20 male subjects completed three treadmill runs to exhaustion (5 days apart). In each session, all subjects performed an incremental running test after WU (20 min at 70% maximum heart rate (HR)), after PC (wearing a cooling vest (0 degrees C-5 degrees C) for 20 min at rest) or without particular preparation (C). After a 5-min break, the exercise protocol commenced at a workload of 9 km/h and was increased by 1 km/h every 5 min until the point of volitional fatigue. Running performance, HR, blood lactate concentration, tympanic temperature and skin temperature were measured in each trial.
In the PC condition, the running performance (32.5 (5.1) min; mean (SD)) was significantly (p<0.05) higher than in WU (26.9 (4.6) min) and in C conditions (30.3 (4.3) min). During the first 30 min of testing, HR, tympanic temperature and skin temperature were significantly (p<0.05) lower after PC than after WU. There were no significant differences in lactate concentration; however, there was a trend to lower values after WU.
The use of an ice-cooling vest for 20 min before exercising improved running performance, whereas the 20 min WU procedure had a distinctly detrimental effect. Cooling procedures including additional parts of the body such as the head and the neck might further enhance the effectiveness of PC measures.

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    • "Of the 13 studies included in the review, 8 studies attained a PEDro score of 6/10 [16-19,26,27,40,41], 4 attained a score of 5/10 [24,25,42,43], and 1 study received a score of 4/10 (Table 3) [25]. Sample size calculations were not performed by any of the reviewed studies. "
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    ABSTRACT: Background Endurance exercise capacity diminishes under hot environmental conditions. Time to exhaustion can be increased by lowering body temperature prior to exercise (pre-cooling). This systematic literature review synthesizes the current findings of the effects of pre-cooling on endurance exercise performance, providing guidance for clinical practice and further research. Methods The MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus databases were searched in May 2012 for studies evaluating the effectiveness of pre-cooling to enhance endurance exercise performance in hot environmental conditions (≥ 28°C). Studies involving participants with increased susceptibility to heat strain, cooling during or between bouts of exercise, and protocols where aerobic endurance was not the principle performance outcome were excluded. Potential publications were assessed by two independent reviewers for inclusion and quality. Means and standard deviations of exercise performance variables were extracted or sought from original authors to enable effect size calculations. Results In all, 13 studies were identified. The majority of studies contained low participant numbers and/or absence of sample size calculations. Six studies used cold water immersion, four crushed ice ingestion and three cooling garments. The remaining study utilized mixed methods. Large heterogeneity in methodological design and exercise protocols was identified. Effect size calculations indicated moderate evidence that cold water immersion effectively improved endurance performance, and limited evidence that ice slurry ingestion improved performance. Cooling garments were ineffective. Most studies failed to document or report adverse events. Low participant numbers in each study limited the statistical power of certain reported trends and lack of blinding could potentially have introduced either participant or researcher bias in some studies. Conclusions Current evidence indicates cold water immersion may be the most effective method of pre-cooling to improve endurance performance in hot conditions, although practicality must be considered. Ice slurry ingestion appears to be the most promising practical alternative. Interestingly, cooling garments appear of limited efficacy, despite their frequent use. Mechanisms behind effective pre-cooling remain uncertain, and optimal protocols have yet to be established. Future research should focus on standardizing exercise performance protocols, recruiting larger participant numbers to enable direct comparisons of effectiveness and practicality for each method, and ensuring potential adverse events are evaluated.
    BMC Medicine 12/2012; 10(1):166. DOI:10.1186/1741-7015-10-166 · 7.25 Impact Factor
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    • "Finally, both interventions reduced T skin , but the greater decrease was obtained with CWI by exposing approximately twice as much skin surface area than V, resulting in a greater afferent stimulation of water on the entire body (Castle et al. 2006). Reduced HR with V and CWI have been demonstrated in previous cooling investigations (Kenny et al. 2011; Uckert and Joch 2007; Yeargin et al. 2006). Hornery et al. (2005) also observed a trend towards lower _ VO 2 and HR values following V during a constant cycling exercise at 75% _ VO 2max in a similar environment (21 °C vs. 20 °C in the present study). "
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    ABSTRACT: The aim of this study was to examine the effects of cool water immersion (20 °C; CWI) while wearing a cooling jacket (Cryovest;V) and a passive control (PAS) as recovery methods on physiological and thermoregulatory responses between 2 exercise bouts in temperate conditions. Nine well-trained male cyclists performed 2 successive bouts of 45 min of endurance cycling exercise in a temperate environment (20 °C) separated by 25 min of the respective recovery interventions. Capillary blood samples were obtained to measure lactate (La⁻), sodium (Na⁺), bicarbonate (HCO₃⁻) concentrations and pH, whilst body mass loss (BML), core temperature (T(core)), skin temperature (T(skin)), heart rate (HR), oxygen uptake , and minute ventilation were measured before (Pre), immediately after the first exercise bout (Ex1), the recovery (R), and after the second exercise bout (Ex2). V and CWI both resulted in a reduction of T(skin) at R (-2.1 ± 0.01 °C and -11.6 ± 0.01 °C, respectively, p < 0.01). Despite no difference in final values post-Ex2 (p > 0.05), V attenuated the rise in HR, minute ventilation, and oxygen uptake from Ex1 to Ex2, while T(core) and T(skin) were significantly lower following the second session (p < 0.05). Further, CWI was also beneficial in lowering T(core), T(skin), and BML, while a rise in Na⁺ was observed following Ex2 (p < 0.05). Overall results indicate that cooling interventions (V and CWI) following exercise in a temperate environment provide a reduction in thermal strain during ensuing exercise bouts.
    Applied Physiology Nutrition and Metabolism 07/2012; 37(5):965-75. DOI:10.1139/h2012-077 · 2.34 Impact Factor
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    • "In regard to warm-up prior to exercise in the heat, evidence indicates that the increase in thermoregulatory strain may have negative consequences for ensuing prolonged exercise performance (Uckert and Joch 2007; Bishop and Maxwell 2008). However, the benefits for contractile function, VO 2 , psychological arousal and athlete readiness cannot be ignored. "
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    ABSTRACT: Exercise in hot conditions alters the physiological response to the ensuing exercise bout and may hasten the onset of fatigue. Regardless of the environment, often preexercise procedures are employed in order to ensure the commencement of exercise in an optimally prepared state to perform. Two such pre-exercise procedures often proposed as being of benefit involve warming up and pre-cooling, respectively. While both have been shown to have ergogenic benefits, they are somewhat contradictory in nature. It is well documented that optimal muscular function of the contractile fibres occurs with an increased muscle temperature. Accordingly, the practice of a warm up prior to exercise commencement is endemic to most sports and athletes and is often based on the premise of increasing muscle temperature. In contrast, it is equally well documented that reducing body temperature by cooling the periphery of the body, including the musculature, is also ergogenic for exercise performance. Accordingly, the practice of pre-cooling is regularly used by athletes from a range of sports and environments. This contradiction between increasing and decreasing respective body temperatures to improve exercise performance raises interesting questions regarding the mechanisms behind the regulation of exercise in the heat. Consequently, the underlying physiological mechanisms to both warm up and pre-cooling procedures are seemingly related to thermoregulatory control. As such, this chapter will review the respective literature on both warm up and pre-cooling in relation to exercise in the heat. Included in this synthesis of relevant literature will be the physiological and performance responses to these respective pre-exercise interventions in the heat. Additionally, a comparison of the respective roles and interaction of both procedures will be discussed and finally, recommendations for the integration of both practices will be provided.
    Body Temperature Regulation, Edited by A.B. Cisneros and B.L. Goins, 01/2009: pages 209-226; Nova Science Publishers Inc.., ISBN: 978-1-60741-282-3
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