Pre-cooling: key to success in hot and humid conditions?

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Having an increased body temperature during exercise is commonly referred to being prepared and ready for whatever the activity is. It is a standard procedure for a warm up, when following the RAMP protocol. This means that muscles can become more pliable and that sweat evaporates from the skin more efficiently therefor regulating the temperature in the body. However, when in hot and/or humid conditions the necessity to raise the body temp even more can be detrimental to performance.

When in hot and/or humid conditions the body’s ability to control its temperature and muscle blood flow around the body (Thermoregulation) is compromised and so the ability of the athlete to continue performing optimally is jeopardised. This is due to the specific influence heat has on the cardiovascular system due to its regulatory control of the body’s level of physical homeostasis (Taylor and cotter, 2008). When body temp is particularly higher than usual, then an ‘Oxygen Debt’ is produced where the body cannot fulfil the demands of the skin and blood flow to the muscles. Sweating remains functional, but the core temperature of the body accelerates. For those taking part in longer distance events, combined with hot and/or humid conditions an athlete will have to reduce their exercise intensity or risk heat- related injury (Maughan, 2010).

The combination of long distance events and hot conditions can be a volatile mix with issue arising when in hot and/or humid conditions when taking part in events longer than 5 minutes. Tyler and cotter (2006) show that the longer distance and time an event goes the greater increase in body temperature. For those events under 5 minutes and in the anaerobic (ATP-PC and glycolytic systems), regulating body temperature is less of an issue due to its minimal involvement of the cardiovascular system.

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Studies (Quod et al, 2006;Sunderland and Neil, 2008) show a 6% decrease in performance in hot (32°C) conditions compared to moderate (23°C) with levels of RPE (Rate of Perceived Exertion) and perceived thirst being higher compared to moderate temperature conditions. So by reducing body temperature of an athlete in hot conditions it can cause a more optimal performance and prevent a negative influence of the conditions.

Pre cooling

A strategy to reduce body temperature, prior and between events is that of Pre cooling. This involves the reduction of body temperature to allow the body to perform in an optimal state by allowing the body increased time to reach the critical core temperature, which is so detrimental to performance. Quod et al (2006) outlines methods of doing so which are Internal cooling (Core) and External cooling (Skin). The methods that will be analysed will be Cold-water immersion, the use of cooling garments and cold-water ingestion.

Cold water immersion involves an athlete placing there whole body into cold water or a temperature lower than the bodies, with an aim to cause a reduction in heat production and increase heat storage capacity (Booth, 1998). Marino and Booth (1998) suggest reducing the temperature of the water of a 30-60 minute period as to prevent ‘shivering’.

Jones et al (2012) shows the practical and successful application in wider research, however, for those in the sub-elite this method may be unrealistic. To take an ice bath or the equipment necessary to carry this out can be unrealistic for those weekend participants in cycling, running or other cardiovascular demanding sports. A compromise for the sub-elite could be that of cold showers, as most facilities would have this option.

Cold-water ingestion causes lower skin surface and intramuscular temperatures due to heat energy being transferred to melt the ‘ice slush’ inside the body. Jones et al (2012) show the wider research showing the success of this type of pre-cooling method.  With it’s cheap an easy attributes and supported research this is a viable option for those at elite and/or sub-elite levels.

Cooling garment (towel/jacket). This may include such items as an ice vest as used by the AIS in 1996 for the Olympic games in Atlanta, with athletes feeling a higher perceived effort after wearing it during their warm up. However Jones et al (2012) show that there is no significant evidence to show that this is an effective pre-cooling method.

I have conducted a small investigation at university into its application with myself and another student rowing 2x2000m on a rower separated with a 15-minute rest period between attempts. 2 Methods of pre-cooling were attempted with me using an external strategy of a cold towel to the back of the neck and the other person using an internal strategy of drinking iced water.  The Results showed that the external towel had a greater effect on recovery between 2000m row efforts. The application that this could have to wider research is limited but as with all sport science investigations it can vary per individual.

Consequently, the use of pre-cooling for those in cardiovascular activity can be great. The research shows the most effective method is that of Cold-water, whole body immersion but it may not be the most realistic. So, it is therefor up to the athlete to determine their creativity in doing so. Whether this be a cold shower before activity or the use of cold-water ingestion, which is easy to make and to use due it, s cheap an practical attributes.

For a summer, where sport is prevalent within hot climates such as the World Cup in Brazil and many middle to long distance races, the application of these methods could be vital. As football can be seen as a cardiovascular activity with variating levels of intensities it can be applicable. This could be done by using cold-water ingestion during games around sides of the pitch, with a previous history of stoppages during play, to allow for fluid intake. By combining the need for hydration with thermoregulation, it can give teams that edge on other teams who don’t use it.

References:

Marino, F & Booth, J. (1998). Whole body cooling by immersion in water at moderate temperature. Journal Sci Med Sport. 1, 73-82.Jones et al. (2012). Pre-cooling for endurance exercise performance in the heat: a systematic review. BMC medicine. (10), 1-20

Maughan, RJ. (2010). Distance running in hot environments: a thermal challenge to the elite runner. Scandinavian journal of medicine science and sports. 20, 95-102

Qoud, MJ et al . (2008). Practical precooling: effect on cycling time trial performance in warm conditions. Journal of sports Sciences. 26, 1477-1487.

Sunderland, C., & Nevill, M. E. (2005). High-intensity intermittent running and field hockey skill performance in the heat. Journal of sports sciences, 23(5), 531-540.

Taylor, N & Cotter, J. (2006). Heat adaptation: Guidelines for the optimisation of human performance. International SportMed Journal. 7 (1), 33-57

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