One of the biggest challenges that endurance athletes face is staying cool, especially for athletes that participate in triathlon or long-distance running (i.e., marathons or ultra marathons) as it is nearly impossible to avoid racing in the heat of the day. When it comes to staying cool and avoiding overheating, which can dramatically affect performance, maintaining adequate hydration is the first priority.
In addition to adequate fluid intake, there are a variety of methods that athletes use to combat the heat and maintain a lower core body temperature. There are many methods out there, and they range in sophisitcation from something as simple as pouring water over one’s head to fancy cooling sleeves and garments. When I am unsure of what truly works and doesn’t work, I like to turn to the available research to come to a decision. There has been a recent surge in the research examining various cooling methods for endurance athletes exercising in the heat, with the research identifying two primary cooling method categories: 1) precooling methods and 2) percooling methods. Precooling methods are cooling strategies that one would undertake prior to training or racing (e.g., sitting in an ice bath to lower body temp.), whereas percooling strategies are those that one would undertake whilest training or racing (e.g., pouring water over one’s head).
In the research realm, the highest quality evidence is considered that obtained from a meta-analysis, which is basically a quantitative analysis of many randomized controlled trials. A meta-analysis conducted by Bongers and colleagues in 2014 (1) did exactly that and summarized the effectiveness of different precooling and percooling methods on performance in cyclists and runners exercising in hot conditions. The different precooling methods that were examined included: (a) cold water immersion, (b) cold water/ice slurry ingestion, (c) wearing an ice vest, and (d) cold pack application. The different percooling methods that were examined included: (a) cold water ingestion, (c) wearing an ice vest, and (d) cold pack application. Although some of these cooling methods may seem a bit strange, they are similar to real-world cooling methods used by athletes such as drinking cold water, pouring cold water over one’s head, stuffing ice or cold sponges down a race suit, or wearing cooling garments.
The researchers of this study found that both precooling and percooling startegies improved performance. In fact, there was a 6% improvement in cycling/running performance when athletes applied precooling methods, with a mixing of cooling methods being the most effective (i.e., ingesting cold water/ice slurry drinks, immersing oneself in cold water, and applying cold packs or wearing an ice vest). There was a 10% improvement in performance when athletes applied percooling methods, with the application of an ice vest the most effective when compared to cold water ingestion and the application of ice packs.
So, what does this mean for you as an endurance athlete? Well, the researchers of this study pointed out that it seemed as though the cooling methods that worked the best were those that affected the largest surface area of the body. For athletes training and competing in warm weather, this means that the most effective cooling strategies are a combination of methods affecting as much of the body as possible. The following table provides some examples of precooling and percooling methods that may help you maintain a lower core temperature whilest training and/or racing in warm conditions:
Obviously, an athlete has to factor in what is practical and tolerated before undertaking any of the strategies mentioned above. For some athletes, sitting in a tub of cold water or walking around with cold packs stuffed down your clothing prior to a race may not be practical or very well tolerated. When the weather is warm, the goal of cooling methods before and during training/racing is simply to lower your core body temperature so that your body doesn’t have to work overtime to cool itself down. By lowering your core body temperature and taking some of the heat strain off your body, you will perform better than if you were to let your body temperature continually creep upwards.
As with anything else, be sure to try these cooling methods out during training before trying them for for the first time in a race. If you are going out for a long training ride or run in the heat, try the above strategies out and see how it affects you. Nailing down both your hydration and your cooling strategies, both before and during training/racing, will help you maintain or improve your performance in the heat.
1. Bongers, C. C., Thijssen, D. H., Veltmeijer, M. T., Hopman, M. T., & Eijsvogels, T. M. (2014). Precooling and percooling (cooling during exercise) both improve performance in the heat: a meta-analytical review. Br J Sports Med, bjsports-2013.
Happy Training and Racing... and stay cool out there!
-Ryan Eckert, MS, CSCS
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