Endurance sports and events, for the purposes of this information, are defined as those events lasting longer than two hours. They can pose both nutrition and hydration challenges to the participant. Events range widely from sailing races and tennis matches, to hill walking, and right through to more obvious pursuits such as marathons, road cycling, triathlons or multi-day events, including adventure races.
The preparation or training commitment for athletes is often proportional to the competition duration, and adequate training nutrition and hydration play a very important part. Long training sessions are frequent as are training days with multiple sessions where athletes need to ‘back up' quality sessions. If you allow yourself to become significantly dehydrated during each training session, it becomes increasingly difficult to recover between sessions, resulting in subsequent training sessions suffering as a result. Dehydration is not something you can "train yourself to get used to" - all that will happen is reduced performance and a risk to health. Make use of your basic training sessions to assess your sweat rate (see "How To Determine Your Personal Sweat Rate") as well as to practice hydration strategies that you will later use in competition. Examples include using a belt-type water bottle carrier (often called a "fuel belt"), a camel back system, setting up a training course which has water stops along the way (set out your own water bottles), installing an extra cage or two to hold extra bottles on the bike, or having friends / family come out to help you carrying fluids on their bikes. After the training session, make sure you rehydrate effectively.
How much should I drink?
Actual fuel and fluid requirements are individual and can vary enormously, making it futile to state an "average" sweat rate. Fluid should only be consumed at a rate which is just below, or matches, your sweat rate and no more. The aim is to drink enough to keep fluid losses to under 2 % of body weight1,2.
As a general rule, the gut can tolerate up to 60 g of carbohydrate and up to 1 L of fluid per hour of exercise. The more dehydrated you become, the less your gut will tolerate so start taking in fluid as soon as you can once you start. It is imperative that you trial your fluid and food intake first during training sessions (especially in long sessions) so that you understand your own stomach capacity and level of tolerance and comfort. This later aspect can be trained to increase to a degree, so push the boundary a little and see what you can achieve comfortably3.
What should I drink?
For most endurance events, performance can be limited both by dehydration and by insufficient fuel supplies. If you have the opportunity to use a carbohydrate gel, water is the optimal solution to drink with them as otherwise you'll end up with too concentrated a solution in your stomach2. If practicality or gastrointestinal tolerance means eating isn't possible, then using a sports drink such as POWERADE ION4 will help to achieve both fuel and fluid needs at the same time. For those with high sweat rates or particularly long events, it may be necessary to add some extra salt to help ensure good retention and uptake of the fluid into the body1,3. This could be done via food if possible, adding a teaspoon of salt to each water bottle, or using an electrolyte powder or ‘salt' capsule. (If you are considering adding salt to your drinks, consult a sports dietitian first to ascertain the best amount of salt for your specific purposes.) If the weather is hot, try to get access to some cool fluids wherever possible in order to help keep your core body temperature from rising too much. If you are competing in ultra-endurance events, "flavour fatigue" can occur. It can be useful to vary your fluid and food intake to ensure variations in taste so that you maintain a consistent drive to drink and eat. This is a great time to make use of the delicious varied flavours of POWERADE ION4!
But won't being lighter in weight help my performance?
In some sports, having a higher power/weight ratio is potentially beneficial for performance - such as hilly cycling or running events. Therefore, it might make sense to think that a small amount of dehydration (and therefore a lighter weight) could benefit performance more than the negative impact the dehydration has on you. However, when put to the test, this doesn't appear to hold true, especially in warmer climates4. A similar argument can be made when considering the potential impact on race time of stopping to get a drink at a drink station, even when conditions are milder in temperature.
What happens if I drink too much?
For more information, refer to the section on Hyponatraemia
Simple Tips for hydrating well during endurance events
Manage training sessions effectively by ensuring adequate fluid intake. This may require planning of fluid stops during an event according to locations of pre-positioned water bottles, use of a "camel-back" style system or a fuel / drink belt.
For triathletes and cyclists, a front mounted hydration system (sits on the front of the bike) enables you to sip on sports drinks like POWERADE ION4 with ease and without bending over or holding the bottle.
Use training sessions to practice drinking (and eating) strategies for competition. This includes practicing drinking from a cup when on the move if you're involved in running events, as this is the most common form of delivering fluid at drink stations.
Assess your sweat rate during various training sessions (different temperatures, distances and intensities) so you have a clear plan for required fluid intakes when it comes to a competition. Aim to drink enough to match your sweat rate as closely as you can in order to minimise dehydration - but avoid drinking more than you sweat.
If it's hot, try freezing your drinks overnight so they're still cold by the time you get to drink them.
Do your homework and find out what and where fluids will be available during the competition so that you know what you need to take with you. You may be able to place your own drink bottles out at these stations, or pack a "special needs bag" for yourself to pick up. Always pack at least one extra water bottle in case you lose or drop one and some easy-to-eat food (such as honey or vegemite sandwiches, bananas, or a sports gel) if you're able to eat.
Start your training session or event in a well hydrated state. As a general guide, consume 500 ml fluid (or 6-8 ml/kg body mass) of sodium-containing fluid (or water taken with food) as a single drink two hours before exercise2.
Start drinking early and drink regularly throughout your event (such as every 15-20 mins). The longer you wait, the more likely it is that your gut will not absorb fluid as readily as the blood supply will get diverted from the stomach to the exercising muscles. Keeping a small "bolus" of fluid in the stomach helps with absorption of the fluid.