There is no getting away from it, when we exercise, we get hot, and when we get hot we sweat. The harder we push, the hotter we get and the more we sweat, until beads of water drip from every pore leaving a film of crystalline electrolytes encrusted on our face, our body & on our clothes. Sweating, however, shouldn’t be something we are embarrassed about nor something we should try to stop (deodorants…just don’t get me started). It is an extremely efficient cooling system, one that allows us athletes to push our bodies to new extremes. In fact, sweating is actually one of those things that separate us from other mammals in the animal kingdom. The fact that we can cool ourselves through skin perspiration, rather than panting, means that we can perform at high intensity and in extreme heat, without needing to hide away under shade.
The downside of cooling ourselves through sweating is that we need to replace the lost water and electrolytes. If we don’t, then athletic performance will be impaired and our health can also be put at risk.
There is little debate in the scientific world that endurance athletes need to rehydrate. Proper hydration during training and competition can enhance performance, delay fatigue, avoid thermal stress, such as heat stroke, maintain plasma volume, and prevent the injuries associated with dehydration. However, it is not as simple as ‘drink, drink, drink’ as excessive hydration is as damaging to the body and performance as dehydration. A hyper-hydrated state can lead to a condition called exercise-associated hyponatremia (EAH). This is where the concentration of blood sodium (aka salt), a key electrolyte needed for muscle contraction, becomes significantly diluted due to over consumption of water. Reaching hyper-hydration either before or during a race can be harmful to performance. A recent study on mountain marathoners’ hydration levels found that athletes who were hyper-hydrated at the start of the race were more likely to DNF.
As both dehydration and hyper-hydration negatively impacts on performance, the key question is how much liquid, and what liquid, is best to consume to optimise athletic performance.
Professor Tim Noakes, in his 2012 book Waterlogged, suggests to ‘drink water to thirst’, i.e. an athlete should drink as and when they feel the need. This approach is enticing for it’s simplicity. It may be effective for experienced athletes with a strong knowledge of their specific hydration needs. However, this is a bit of a ‘winging it’ approach to hydration. While it may be effective when exercise duration is short, intensity is low, and/or the weather is cool, i.e. when you are unlikely to become dehydrated in the first place. It is much harder to effectively put this hydration strategy in place when an athlete pushes harder and sweats more, as is the case in long endurance races, especially if they are in hot climates.
Like with so many things in life, we are all unique with our own specific hydration needs. Several factors must be taken into account when developing a hydration strategy. Firstly, you must consider your sweat output levels. Our perspiration rates can range anywhere between 0.5 to 2 litres per hour, impacting on the amount of liquid we need to take on. Then, when you add on external factors, including temperature, humidity, & exercise intensity it is clear there is no one-size fits all. In fact, there is not even a ‘one-size fits one athlete’ as each race or training session will have differing external factors. Therefore, it is important to practice different hydration strategies in training to get a range that works for you.
To help you devise a strategy that works best for you we recommend the following steps to hydrating:
- Drink 500ml of a fluid solution containing 0.5-0.7g/l sodium 1 to 2 hours before training or competing.
- Consume 600-1200ml of this same concentrated liquid per hour of exercise (for training lasting longer than 1 hour).
- Depending on how your body reacts, add more or less liquid until you get a protocol that is perfectly tailored to you.
And always remember never to try anything new in competition!!! Make sure you practice different consumption levels in different weather conditions to ensure you have a range of solutions you know will work for you on race day.