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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    ABSTRACT: To investigate the acute effects of whole-body cryotherapy (WBC) on postural control, we measured postural sway (COP) in a quiet stance with eyes open in four consecutive 20-second tests: before and one, six and 11min after the WBC. Twenty-four healthy young subjects aged 19.3±0.9 were exposed to WBC (-110°C) for two minutes. The time series recorded with a sampling rate of 100Hz was used to evaluate postural performance (COP variability) and strategies (COP frequency and entropy). There were no differences between the pre- and post-WBC values of these measurements in the frontal plane; however, in the sagittal plane postural sway increased immediately after WBC (p<0.05) and remained elevated throughout the experiment. Deteriorated performance brought about lagged changes in postural strategies, including a decrease in frequency and entropy. These changes remained sustained until the end of the experiment. In conclusion, the WBC caused a drop in complexity, adaptability, and automaticity in postural control, which accounted for specific constraints imposed on the postural system due to cooling.
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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.
    Full-text · Article · Dec 2012 · BMC Medicine
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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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