To avoid dehydration and get the most out of yourself and out of your sports drink, you should drink before, during, and after sport. Powerade Isotonic is perfect for each of these times.

How can Powerade help me before sport?

Drinking sports drinks, such as Powerade Isotonic, before intense exercise helps to ensure that you begin in a well hydrated and well fuelled state. This can be particularly useful if you find it difficult to eat, or find you need many bathroom stops prior to exercising. Starting exercise well hydrated is vital; leaving it until you are on the field or track may be too late. This is particularly crucial for longer duration exercise, or activity undertaken in hot, humid conditions, and even for people whose primary exercise is actually manual labour. Sports drinks like Powerade Isotonic can also help you start with plenty of energy.

How do I make sure that I start my exercise optimally hydrated?
Unfortunately drinking one litre of fluid half an hour before starting your session isn't going to rehydrate you effectively. Instead, this should be undertaken over a period of at least several hours, with around 400-600ml in the 2hr before exercise¹. A good hint is to set up a hydration strategy that suits your lifestyle. Athletes need to ensure they continue their fluid intake consistently in between training sessions. If you are working, ensure that you have access to fluids at hand.

Some suggestions include:

1. Set a timer on your computer / watch to remind you to drink something every hour.
2. Take a drink bottle to work / uni / school and keep it in sight all the time. If you work outdoors, keep it in an esky to keep the fluid cool.
3. Set up a dispenser in your workplace so you always have chilled drinks on hand.
4. Always have something to drink when you have a meal, as many nutrients in meals can help promote adequate hydration².
5. Keep an eye on your urine output throughout the day. Aim to keep it reasonably clear in colour most of the day (although this doesn't count if you've just recently consumed a large volume of fluid in one hit).
6. Fluids can include water, milk, juice, sports drinks, cordial, soft drinks, tea and coffee and can all be “counted” towards total fluid intakes over the day, although you need to consider the impact of their energy content as well.

If you know you’ve left yourself a little short in terms of fluids and food just prior to exercise, try drinking a sports drink, such as Powerade Isotonic before you exercise to top you up. The electrolytes will help your body hold onto the fluid effectively.

How can Powerade help me during sport?

Regular replacement of fluid is the main consideration during any sports event. During exercise, Powerade Isotonic is designed for optimal provision of fluid and fuel. These benefits aren't just for your muscles. By helping to maintain hydration and providing fuel to combat fatigue, Powerade Isotonic can also help your reactions times, concentration and coordination. Powerade Isotonic can help you perform at your peak for longer.

It is recommended to use Powerade Isotonic during training sessions before using it in competition, in order to determine your own individual stomach (gastrointestinal) comfort. You may be able to train your gut to tolerate more fluid if you build your fluid intake gradually¹¹. This can be in the form of plain water for shorter bouts of exercise, but for longer events the fluid should also include small amounts of carbohydrate, like that found in Powerade Isotonic.

In the early 1900's, it was believed that people shouldn't drink during exercise as it was bad for you. Not drinking was meant to "toughen you up". However, research has shown that drinking during many forms of exercise is actually good for you. Obviously, in many sports and forms of exercise, it's not practical to drink - such as a 100m sprint, a judo bout, or during an Olympic rowing or kayaking race! If you're only exercising at a low to moderate intensity for a relatively short time (less than 20-30 minutes), especially in cool weather, then there is no need to take on fluid during the session as you should be sufficiently hydrated before hand.

Why should I drink during exercise?
There are various effects that dehydration has on both performance and on the body during exercise. Please refer to the section on DEHYDRATION for more information.

What should I drink?
The choice of what you drink partly depends on the duration of exercise, the environmental conditions, and personal preference. In exercise of 60 minutes or longer, especially in the heat, there is good evidence supporting the use of a sports drink (such as Powerade Isotonic) over water due to both the electrolytes and the carbohydrate in the drink. If you're not a good drinker, then having fluid with some flavour in it will help you drink more^4,5. However, if you're exercising for less than an hour and in cool conditions, then water may be adequate.

How can Powerade help me after sport?

Powerade Isotonic is ideal for fast replenishment of fluid and fuel to muscles to get you ready for the next training session. This is particularly important for those doing more than one training session per day. It is well recognised that even though sweat rates vary considerably between individuals, voluntary fluid intakes during exercise generally only meet around 50% of fluid needs. Hence, most people finish exercise dehydrated.

Why is rehydrating important?
Rehydrating is important for many reasons, but basically it's to get the body's system back into shape as quickly as possible after exercise. If you don't rehydrate effectively, you can suffer the ongoing effects of dehydration for many hours after exercise - including tiredness, the inability to concentrate, and dull headaches. For those who exercise at least once a day, the failure to rehydrate generally means they may start the next exercise session in a dehydrated state.

When should I rehydrate?
Rehydration should start as soon as practical after exercise, with the overall goal to consume 150 % of the fluid you lost during the session in the next few hours⁶. For example, if you lost 1 kg (1000g) mass during the exercise session, you need to drink 1.5L (1500ml) in the next one to two hours. The reason you drink more than what you sweated is to account for the fact that you continue sweating even when you stop exercising (at least until the body's core temperature returns to normal), and because inevitably some of this volume will end up as urine. It is better to drink to a plan over a period of time, rather than in a haphazard way or all in one go! Planning is especially important in older adults whom, it is now known, have a reduced thirst sensitivity when dehydrated⁷. As most of us already know the 'one hit' drinking plan will generally only result in more of the fluid going into the toilet, not to mention making you feel extremely bloated and uncomfortable! BUT, it doesn't stop there - continue to drink regularly throughout the day, rather than just at meals, in order to maintain hydration levels. If you drank well during the exercise session and didn't lose any weight, don't forget that you still need to drink afterwards as well, as you'll continue sweating for a while.

What should I drink?
Sports drinks can help you rehydrate because they contain water, electrolytes and carbohydrates. Other fluids may be also used to rehydrate, however, they may not be as efficient. For example, water on its own has not been shown to be effective in rehydrating over a four hour period where individuals had dehydrated nearly 2 % during exercise in the heat⁸. Similarly, most soft drinks don't contain enough sodium, which is the key electrolyte influencing rehydration, so would be as ineffective as water in rehydrating you. Despite the commonly held belief that caffeine-containing fluids further dehydrate you, research now shows that caffeine at moderate doses does not promote dehydration at rest or during exercise. However, such beverages also do not provide improved rehydration compared to water or a non-caffeinated drink⁹. If you're going to eat a meal soon after exercise, then water should be a sufficient rehydration fluid¹⁰ since the meal generally contributes electrolytes and nutrients which help promote uptake of the fluid you consume (Note: some foods contribute fluid themself - such as fruit, vegetables and dairy products)⁷.

If you don't plan on eating, then a sports drink such as Powerade Isotonic has the advantage of sodium (salt) which helps your body retain and use the fluid more effectively, as well as carbohydrate to help recover muscle fuel stores. The other advantage of a sports drink is that it doesn't switch your thirst receptors off prematurely - in other words, it keeps you sensing "thirst" until such time that you are adequately rehydrated.

How to determine your personal sweat rate

Before you can win, you need to know how much you lose. Your sweat rate is used to estimate how much fluid you need to replace during and after sport. This can be measured by looking at your weight change over several exercise bouts to get a feel for your own personal sweat rates under different exercise and environmental conditions, where:

Sweat loss (mL) = change in body mass (g) + fluid intake (mL) - urine losses (g)

Weighing yourself, immediately before and after exercise gives you a good idea of how much fluid you actually lose during exercise. The difference in weight represents fluid loss (ie. 1kg loss equals to approximately1L (1000mL) sweat). Once you know how much you lose per hour of exercise, generally it's best to replace 80% while exercising (so in this case, 800mL). After you finish exercising, you should drink 150% of your fluid deficit. For example, if you are still 400mL down will mean replacing 600mL fluid after exercise.

Sweat rates vary greatly between individuals, with females tending to sweat less than males. For example, even within one sporting team doing similar work, sweat rates can range from 600 - 1200 mL/hr for females, and 800-1400 mL/hr for males¹. Your personal fluid target should be scheduled, so that you start drinking early on and consistently throughout the exercise bout rather than leaving it all to the later stages. If you leave it too late, it's likely your stomach won't be as receptive to absorbing the fluid since the blood flow will have shifted to other areas of your body, such as your muscles. These fluid intake targets should be practiced in training so that you train yourself to drink more, and you can make sure you're drinking within gastrointestinal (stomach) tolerance.

To calculate how much sweat you lose when training or in competition, you will need to:

1. Weigh yourself (with minimal clothing - eg. no hat, socks, shoes, t-shirt) before exercise
2. Exercise for one hour at your targeted intensity**
3. Track your fluid intake during exercise (measure in mls)
4. Record weight (with minimal clothing) after exercise

** One hour is recommended to get a reliable representation of sweat rate expected

The above method determines your hourly sweat rate by adding the difference in your weight before/after exercise to the fluid consumed (step 3). Note the environmental conditions on this day, and repeat the measurements on another day when they are different (cooler, warmer). This will give you an idea of how different conditions affect your sweat rate.

Disclaimer: This method is only a rough estimate of recommended fluid intake. For serious training and competing requirements, please consult a sports dietitian.

Being well hydrated helps you perform at your best

Benefits of being well hydrated
Starting exercise properly hydrated gives you the best chance of minimising dehydration as you train, play, or race hard. It can also help keep your blood volume at optimal levels, and allows you to sweat to remove heat effectively. Athletes that are well hydrated are also likely to have better concentration and skill learning ability. So there are many good reasons to use Powerade Isotonic to keep you well hydrated!

What happens to your body when you are dehydrated?
The following are some examples of what could happen to your body when you are dehydrated:

• Thicker blood: When you start to dehydrate, your blood volume decreases and starts to thicken and slow. This puts pressure on your heart, making it work harder to pump oxygen and glucose to your muscles.
• Muscles fatigue: Your active muscles lose muscle strength and fatigue.
• Mental fatigue: Reaction times, concentration and decision making ability decrease.
• Overheating: As the cooling effect of sweating decreases due to less fluid in your body, your core temperature rises.

Signs and Symptoms of Dehydration
It's important to recognise the following signs of dehydration. Some of the symptoms include:

• Increased thirst
• Dry mouth
• Light-headedness
• Fatigue
• Impaired mental focus
• Low / Dark urine output
• Dull headache
• Increased heart rate

When you're thirsty, it's your body's way of saying you're already dehydrated. As little as 2% dehydration (that is, 1.4kg loss in a 70kg person) may lead to a noticeable decrease in performance. Dehydration results in increased body temperature, increased heart rate, increased ratings of effort, reduced physical performance, and reduced mental performance¹. Hence, drinking during exercise can help minimise detrimental effects, especially during more prolonged and / or higher intensities of exercise. There is also now some evidence that drinking cool fluids actually helps keep your body temperature down when you're exercising in the heat as well2. Mild dehydration can affect physical and mental performance, while severe dehydration can be life-threatening. Dehydration can develop quickly under some conditions, such as extreme heat. To avoid dehydration and perform at your best, pay attention to your thirst and make sure you consume plenty of fluids during the day.

Using urine colour as an indicator of hydration
The colour of urine is the simplest indication of your level of hydration, and is usually accurate. If it's clear or lightly coloured you're generally fine (unless you've just had large volumes of water without a sports drink or salty food - hence not retaining any fluid consumed); if it's dark yellow you're dehydrated (or have consumed large amounts of vitamin B and/or C through a supplement).

How much should I drink?
Check out Hydration Calculator to estimate rough fluid requirements for your exercise or sport.

Can I drink too much? - Avoiding hyponatraemia

Whilst remaining well hydrated is key to feeling great and performing at your best, you need to be careful not to drink too much, or over-hydrate. Over-hydrating can result in a rare but potentially fatal condition known as hyponatraemia, or low sodium levels in the blood. This occurs when more fluid is consumed than can be effectively cleared by the kidneys (which tend to reduce their function during exercise). The symptom of hyponatraemia can be similar to dehydration - headaches (due to swelling of the brain), disorientation, nausea and vomiting ¹. Most reports of hyponatraemia have occurred in ultra-endurance running events (often greater than six to eight hours), with those most at risk being slower runners with plenty of opportunity to drink. Drinking a sports drink doesn't necessarily reduce the risk, although it may help to lower the risk if volumes consumed and sweat rates are matched. The main issue is to not drink so much that you gain weight during the event^2,3, so aim to finish exercise at the same, or a slightly lower, body weight than that with which you started. Knowing your own personal sweat rates under different weather conditions is a great way to ensure the fluid volume you take in is close to what you need - not too much and not too little. See the "How to Determine Your Personal Sweat Rate" for help with this.

Hydration Under Different Environmental Conditions

The effect of dehydration on performance varies across different weather conditions, with dehydration during exercise in the heat provoking larger performance decrements than similar activity in cooler conditions due to the combined effects of heat and dehydration¹. Similarly, different environmental conditions alter the risk and rate of you becoming dehydrated. Furthermore, there are many people who have to work under varying environmental conditions, such as miners and military personnel, where the impact of dehydration on work output can be substantial. Understanding the risks and being conscious of your hydration practices are important components of optimising performance at work and on the field.

Fluid intake in the heat
Both dehydration AND exercising in the heat have independent effects on heart rate, body temperature regulation, concentration and performance - in combination, the effects are additive^2,3. The effects of dehydration tend to be progressive (i.e. the larger the dehydration, the greater the negative effect on performance). In extreme cases, prolonged exertion in the heat combined with dehydration can increase the risk of heat stroke and heat illness, and even acute kidney failure resulting from the breakdown of muscle contents³.

Knowing how your own body responds when exercising in the heat is very important and will provide a baseline. Commencing exercise well hydrated, and maintaining a fluid intake pattern which matches sweat losses as closely as tolerable (i.e. without causing gastrointestinal discomfort), are essential for minimising the degree of dehydration incurred during exercise in the heat. In the heat, consideration should also be made for active cooling strategies, such as ice towels, ice vests, and cool water sprays. Use the Powerade Hydration Calculator to determine fluid required for your particular exercise or sport. For extreme conditions use your sweat rate to guide fluid intake (see "How To Determine Your Personal Sweat Rate).

Fluid intake in the cold
The risk of dehydration during exercise in cooler weather conditions can be as high as in hot conditions. Many sports are played indoors, and/or people train with more clothes on, so their actual sweat rates can be close to those in warmer conditions. In contrast, most people drink much less in cooler conditions. The net result of less fluid but similar sweat rate can lead to similar levels of dehydration being incurred in cooler climates to those in warmer conditions. For example, whilst the average sweat rate for footballers in summer training is higher than winter training (1.46 versus 1.13 L/hr), the fluid intake during training during winter was less than half that in summer (650 ml/hr in summer versus 280 ml/hr in winter), so the overall dehydration incurred was slightly higher (1.59% in summer, 1.62% in winter)³. However, evidence suggests that for the same level of dehydration, there is more impact on performance in hotter rather than cooler conditions ⁴.

So, the important message for those exercising in cool environments is to still pay attention to fluid intake as substantial dehydration can still occur. Individuals need to be aware of their sweat losses when exercising in the cold, and to drink according to their sweat rates.

Fluid intake at altitude
Many sports are undertaken at higher altitudes - such as winter sports, mountain climbing, and aerial sports. Athletes can also take advantage of training at higher altitudes to help boost their performance in critical events. At altitude, the air is thinner in terms of oxygen supply, but is also drier, resulting in more fluid being evaporated from the body passively (from the airways and the skin). This is the reason why people get dry throats and cracked lips in the first few days of being at altitude. There is evidence that fluid shifts around the body contribute to acute mountain sickness (altitude sickness), ⁵.

In addition to drier air, higher altitudes tend to be cooler, which as discussed earlier, reduces the drive to drink. Therefore, increasing the volume of fluid consumed to counteract the increased dehydration of altitude is important. The focus should be on maintaining urine output (pale in colour), as well as ensuring fluid lost during exercise is adequately compensated.

Fluid intake when travelling
Many forms of travel, such as airlines and air-conditioned buses, involve sitting in much drier air than that to which most of us are usually exposed. This "dry air" promotes greater fluid loss than being in humid air, mainly from the skin and airways via evaporation. Hence, although individuals are not exercising, fluid intake should be sustained at a consistent rate to ensure arriving well hydrated. The other benefit to sustaining hydration during travel is that it generally results in more toilet visits, which helps keep muscles and circulation moving as you walk around.

Hydration for Team Sport Athletes

Hydrating when playing team sports can be difficult as some have rules which only allow fluid consumption at particular times. Unless sweat rates are relatively low, it is generally inevitable that some degree of dehydration will be incurred during team sports - the goal is to minimise the degree of loss. Therefore, you must take every possible opportunity to hydrate! Skills and fitness can be better developed in the training environment when well hydrated, which will impact on game day performance. Likewise, match performance will be optimised¹.

How to hydrate in training sessions and games
Fluid loss during exercise is very specific to the environmental, physical and clothing demands of sport, and there is also a large individual variation in sweat rates. The environmental factors include temperature, relative humidity, sunshine, and wind, while physical factors include gender, position on the field and the type of sport demands, length of game, size of athletes and perhaps also level of competition. Most research in this area has been done on soccer players. For example, reported sweat rates of elite males in winter competitions range from 710-1770ml/hr², whilst in summer it is from 990-2090 ml/hr ^3,4. In reality, this difference is not great considering the changes in environmental conditions, which may be due to more clothing being worn in winter months. For younger or less elite players, sweat rates may be lower⁴. In other football codes, such as AFL, rugby league and union, sweat rates could be even higher due to larger sizes of the players (there have been reports of sweat rates up to 3.0 L/hr in AFL players). Female soccer players tend to have slightly lower average sweat rates in training as a group than males (around 800 ml/hr in summer), most likely due to their smaller body sizes⁴. Field sport players have consistently been reported to replace, on average, less than 50% of their fluid losses during training or competition^3,4,5. See the section 'How to Determine Your Sweat rate' to help establish your average sweat rate, to help you devise your fluid replacement plans. Alternatively, a qualified sports dietitian can guide you through this process.

What fluids should be consumed?
Most importantly, the drink of choice should be one that you enjoy the flavour of during exercise. Studies have shown that flavoured drinks tend to be consumed more than unflavoured ones⁶. We also know that some sodium (salt) in your fluid increases the retention of the fluid consumed compared to water, and when fluid intakes may not match losses it's extremely important to utilise all of what's consumed as effectively as possible. Considering the duration of many team sports, carbohydrate is also an important consideration for maintaining muscle fuel supplies all the way through. Hence, consuming a sports drink such as Powerade Isotonic has the combined advantages of fluid, taste, sodium and carbohydrate all in a neat package. One word of caution, never wash your mouthguard out with a sports drink or beverage other than water so you do not damage your tooth enamel.

What about the temperature of the fluid?
For maximal absorption from the stomach, the optimal temperature of a fluid is "cool" - around 15oC. However, there is recent evidence that consuming cooler drinks (4-10oC) can help reduce the body's temperature^7,8, as well as increasing the total amount of fluid consumed in hot conditions⁸, which is beneficial when playing in the heat.

Practical tips

1. Use training sessions to practice drinking more and to understand your tolerance to fluid during exercise. You can train yourself to drink more.
2. Always take plenty of fluid to training sessions and to games - it's better to have more than not enough.
3. Take advantage of every opportunity during a game to take a drink.
4. At half time, drink as much as you can tolerate (generally at least 400mL). Try to drink most of this at the start of the break, to allow for maximum time for the fluid to be absorbed.
5. Swallow the drink rather than rinsing your mouth and spitting it out.
6. Whilst pouring cool water over your head may make you feel better in the short term, actually ingesting it will help more over the longer term!
7. Rehydrate effectively after the game / training session by consuming 150% of the fluid lost within the next couple of hours (see the section on "How can Powerade help me after sport?").

Hydration Strategies for Running

Not all running events are the same. The duration of events vary from less than 10 seconds to numerous hours, and runners may have to compete more than once a day, with warm up and cool down time in between. The physique of runners changes from the highly muscular sprinters, through to the lean and low muscled distance runners, ensuring a wide variation in sweat losses. The preparation required to compete in these different events also varies considerably. Acknowledging all of these factors, this information will provide some strategies for each type of event which will help in reducing the risk of dehydration. As with all sports, the onus remains on the athlete to assess their own fluid requirements and trial different strategies in order to determine the most effective means of staying hydrated under a range of different training and competition conditions.

We will start by nominating that short (or sprint) events are up to 400-600 m, while elite category middle distance running events range from 800 m to 10 km events, often run on tracks. Elite long distance running then covers distances from beyond half marathons of 21.1 km, through to ultra marathons. However for the general public, who train a few times a week, we would suggest the 10-15 km distances to be included in the long distance category.

Hydration for sprint distance running
The athletics season for sprinting is typically in summer here in Australia. During competition, the focus should be very much on starting the event hydrated, as there is clearly no time, nor need, to consume fluid during the event. There are no published reports on sweat rates during sprint events, although with such short distances the total volume of sweat lost would still be small¹. More importantly, in competitive environments, there are often multiple events in one day, involving a bit of "waiting around", as well as time spent warming up and cooling down. Therefore, it's important to work on maintaining consistent fluid intake throughout the day, especially after races. In hot environments, try to avoid excessive exposure to the sun and heat. It may be necessary to consider alternative ways to warm down from the previous event (e.g. stretching, ice baths, hot/cold showers), rather than sustained jogging which would contribute further to dehydration. Similarly, during training, although each effort itself may be brief, the total number of efforts undertaken over the duration of training can result in an accumulation of sweat losses which may result in substantial dehydration1. Hence, fluid should always be consumed throughout training sessions, even if the environment is relatively cool since generally warmer clothes are worn, resulting in fairly similar sweat losses to warmer conditions.

Fluid intake recommendations are to consume 6-8 ml/kg (ie. for a 60kg runner, 360 - 480mL) of a sodium-containing fluid like Powerade Isotonic (or water with food) around two hours before your event1. Fluid intake at other times will depend upon duration and intensity of training / competition, and environmental conditions, but should never be so much that body weight is increased above "normal" over the session.

Hydration for middle distance running
For those competitive runners who are very focussed and train regularly, these events are very intense affairs usually lasting less than 30 minutes and fluid intake during the event is not normally required (or possible). Research into the effects of dehydration on middle distance running events is limited, however one older study showed an increase in running times (i.e. poorer performance) over 1.5 km, 5 km and 10 km events when approximately 1.4 kg (~1.9%) was lost through dehydration prior to the event². Therefore, optimising the state of hydration prior to the event is of chief concern, with the primary recommendation being the same as that stated above for sprint events. However, backing up for events in a few days time does mean significant attention should be paid to recovery protocols.

For the general public participant who may want to stay fit and participate in a one off event such as the Sydney City to Surf over 14 km, or a similar event in other capital cities, some of the issues may differ. Being adequately hydrated would be a goal in the preparation phase. The less serious individual will have greater time and opportunity to make use of drink stations that are likely to be situated at points throughout the event, and should therefore be encouraged to consume fluid at a rate that is just below the rate of sweat loss during the event. (See "How can Powerade help me during sport?" and the "How to Determine Your Personal Sweat Rate" for more information.)

Hydration for long distance running
Generally, this is classed as distances of half marathons or longer, and include race walking, requiring at least one hour to complete even in elite level runners. Naturally, just as it is important for a race or event, hydration is an important consideration throughout training for endurance running in order to help ensure optimal training capacity and promote training adaptations afterwards. Training sessions present a perfect opportunity to practice drinking during running events, something which many runners find difficult to do. Not only does this help runners learn how much fluid they can drink without getting stitches and gastric upsets, it can also help teach people how to "drink on the run" without spilling it all over yourself!

Reports of elite level marathon runners indicate sweat losses from 2-8% body mass through the course of a marathon, depending on environmental conditions¹. While world class male athletes may race the half marathon in about one hour and a few minutes, the average runner who has still prepared well may take between 50 and 100% longer, turning the event into a significant endurance task. With reported sweat rates for a half marathon being as least 1.5 L/hr even in winter conditions³, this difference in length of event can be very significant physiologically, as dehydration greater than 2% body mass (e.g. a 1.6kg loss for an 80 kg runner) has been shown to negatively impact on performance^3,4. The longer you spend running at these levels of dehydration, the worse your performance will be, especially in a warm to hot environment. Fortunately, provisions are made for fluid intake during such events, so opportunities to drink should be taken throughout the course of the run. A combination of water and sports drink, such as Powerade Isotonic, should be taken based on your fluid loss (see "How to Determine Your Personal Sweat rate" or "Hydration Calculator" for more details). The carbohydrate and electrolytes available in sports drinks will support fuel provision, as well as allow for better absorption and retention of ingested fluid. If food or gels are consumed, then water is the most suitable fluid to use with this¹. (For further information, refer to "Hydration strategies for endurance events".

Specific Considerations for young runners
The most important issue for kids is hydration. Many children in Australia take part in "Little Athletics" or similar programs, where they can be outdoors training or competing in a variety of events over a whole day. Dehydration is more detrimental to children than it is to adults⁵. Their ability to control body temperature isn't as responsive or effective as an adult so they are more vulnerable to heat-related problems especially in summer⁵. As a result, greater care must be taken with children to ensure they both maintain hydration and have a mechanism to cool themselves. In particular, most children don't drink as effectively as adults, so it is important to monitor total fluid intake during exercise and be actively encouraged to drink.^5,6. For children, water is usually the best fluid to give them.

Hydration Strategies for Endurance Sports

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 weight^1,2. 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 Isotonic 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 body^1,3. 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 Isotonic!

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

1. 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.
2. 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 Isotonic with ease and without bending over or holding the bottle.
3. 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.
4. 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.
5. If it's hot, try freezing your drinks overnight so they're still cold by the time you get to drink them.
6. 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.
7. 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.
8. 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.

REFERENCES:

1. Coyle EF. 2004. Fluid and fuel intake during exercise. J. Sports Sci. 22: 39-55.

2. Shirreffs SM, Casa DJ, Carter R. 2007. Fluid needs for training and competition in athletics. IAAF Consensus Conference, Nutrition in Athletics. (publication pending, J. Sports Sci.).

3. Rehrer NJ. 2001. Fluid and electrolyte balance in ultra-endurance sport. Sports Med. 31: 701-715.

4. Ebert TR, Martin DT, Bullock N, Mujika I, Quod MJ, Farthing LE, Burke LM, Withers RT. 2007. Influence of hydration status on thermoregulation and cycling hill climbing. Med. Sci. Sports Exerc. 39: 323-329.

5. Montain SJ, Cheuvront SN, Sawka MN. 2006. Exericse-associated hyponatremia: quantitative analysis for understanding the aetiology. Br. J. Sports Med. 40: 98-106.

6. Cox GR, Desbrow B, Montgomery PG, Anderson ME, Bruce CR, Macrides TA, Martin DT, Moquin A, Roberts A, Hawley JA, Burke LM. 2002. Effect of different protocols of caffeine intake on metabolism and endurance performance. J. Appl. Physiol., 93: 990-999.

7. Ganio M.S., Casa D.J., Armstrong L.E., Maresh C.M. 2007. Evidence-based approach to lingering hydration questions. Clin. Sports Med. 26: 1-16.