Hydration - Who Needs It?

Hydration - Who Needs It?

We now know that the regular ingestion of fluids is essential for sporting performance. Hypohydration (total body water below normal) impairs the body's ability to regulate heat resulting in increased body temperature and an elevated heart rate. Perceived exertion is increased causing the athlete to feel more fatigued than usual at a given work rate. Mental function is reduced which can have negative implications for motor control, decision making and concentration. Gastric emptying is slowed, resulting in stomach discomfort. All these effects lead to impairment in exercise performance. Most types of exercise are adversely affected by hypohydration, especially when they are undertaken in hot conditions, and negative effects have been detected when fluid deficits are as low as 2% (i.e. a deficit of 1.2 litres for a 60 kg athlete). The good news is that by drinking regularly during exercise, athletes can prevent declines in concentration and skill level, improve perceived exertion, prevent excessive elevations in heart rate and body temperature and improve performance - good justification for every athlete and coach to make fluid replacement a key priority during training and competition.

How much should athletes drink during exercise?

Fluid requirements vary remarkably between athletes and between exercise situations. Fluid losses are affected by: • Genetics - some people innately sweat more than others • Body size - larger athletes tend to sweat more than smaller athletes • Fitness - fitter people sweat earlier in exercise and in larger volumes • Environment - sweat losses are higher in hot, humid conditions • Exercise intensity - sweat losses increase as exercise intensity increases It is impossible to prescribe a general fluid replacement plan that will meet the needs of all athletes. Fortunately, athletes can easily estimate their own fluid requirements by weighing themselves before and after exercise sessions. Each kilogram (kg) of weight lost is equivalent to approximately one litre (L) of fluid. Adding on the weight of any fluid or food consumed during the exercise session will provide an estimate of total fluid loss for the session. For example, an athlete who finishes an exercise session 1 kg lighter and has consumed 1 litre of fluid during the session has a total fluid loss of 2 litres. The Sweat fact sheet in the ‘Hydration’ section discusses sweat losses in athletes and this process in more detail. Once an athlete's individual sweat losses are known, a plan can be prepared to help the athlete achieve better fluid replacement in subsequent exercise sessions. Fluid replacement plans will differ according to the athlete and the opportunities for drinking during the sport. However, where possible it is better to begin drinking early in exercise and adopt a pattern of drinking small volumes regularly rather than trying to tolerate large volumes in one hit. Most athletes can tolerate 200-300 ml every 15-20 minutes but tolerance will vary according to the exercise intensity.

How much do athletes actually drink?

Typically athletes replace 30-70% of sweat losses during exercise. Fluid replacement is an issue for all sports including those such as swimming and water polo conducted in wet environments, and sports conducted in air conditioned stadiums. There are many reasons for athletes failing to drink enough to replace fluid losses. Some athletes are so focused on training or competing that they forget to drink. Some avoid drinking because they fear stomach discomfort. Drinks need to be cool, palatable and conveniently available or they will not be consumed. The sensation of fluid in the mouth sends nerve signals to the brain that switch off the drive to drink. When fluids such as water, juice and cordial are consumed (low in sodium), the desire to drink is often switched off before the athlete has consumed sufficient fluid to match sweat losses.

What should GAA players drink?

Research shows that fluid intake is enhanced when beverages are cool (~15 °C), flavoured and contain sodium (salt). This makes sports drinks an ideal choice during exercise. Sports drinks are not gimmicks. They are legitimate products that are well researched and proven to improve fluid intake and performance. A great deal of science has gone into developing the flavour profile of sports drinks so that they encourage fluid intake during exercise. In addition, sports drinks contain carbohydrate at a concentration (4-8%) that allows refueling to take place during exercise. Several studies demonstrate that use of sports drinks will improve fluid intake. A study conducted in 1999 demonstrated better fluid balance with a sports drink compared to water. Even athletes who prefer to drink water during exercise, demonstrate better fluid intake when forced to drink sports drink. In the past, it was believed that sports drinks only benefited the performance of exercise greater than 90 minutes. However, in recent years, the intake of carbohydrate and fluid has been shown to be beneficial for high intensity exercise of approximately 60 minutes. This makes sports drinks a good option for many types of sporting activity. Water is still a suitable option during exercise. However, water drinkers need to be aware that water does not stimulate fluid intake to the same extent as sports drinks. Drinking to a plan is therefore crucial when drinking water. Don't rely on thirst. Cordial, soft drinks and juice generally contain greater than 10% carbohydrate and are low in sodium. This can slow down gastric emptying and makes these drinks a less suitable choice, especially for high intensity activity. Some athletes, exercising at low intensities may tolerate juice, soft drink and cordial but in most situations, sports drinks are the better option.

Is it possible to drink too much?

Consuming fluid in excess of requirements may cause some gastrointestinal discomfort. In extreme cases, a condition called hyponatraemia can occur. Hyponatraemia (low blood sodium levels) causes symptoms similar to dehydration and is potentially life threatening. It is not common but can occur in prolonged endurance events (> 2 hours) when large volumes of low sodium drinks (such as water) are consumed and sweat losses are small. Those most at risk are small females who have long race times. This group of athletes tends to have small sweat losses and plenty of time to consume large amounts of fluid during the event. Consuming sodium-containing fluids such as sports drink and matching fluid intake to sweat loss lowers the risk of hyponatraemia.

Summary of Fluid Guidelines

• Begin each exercise session in fluid balance. This requires drinking regularly throughout the day leading up to training or competition. Have a drink with all meals and snacks. • Immediately, before exercise commences, consume 200-600 ml of fluid. • Develop a plan for fluid intake for all exercise sessions longer than 30 minutes. Aim to match previous fluid losses as closely as possible (within 1% of body mass). Take into account all the opportunities within the sport. • Begin drinking early in the exercise session and continue to drink small amounts regularly. Sports drinks or water are the best options. • Replace any residual fluid deficit after exercise. You will need to drink 150% of any fluid deficit in the 4-6 hours after exercise to account for ongoing sweat and urinary losses. When fluid losses are high and/or rapid rehydration is required, sodium replacement may be required. Sports drinks, oral rehydration solutions and salty foods can all contribute to sodium replacement.

What can the coach do?

Drinking during exercise does not come naturally to athletes. It is a skill that needs to be developed and practiced. Coaches can help athletes by:

• Recognising the importance of fluid replacement during exercise and creating a supportive environment. • Arranging for athletes to be well educated regarding hydration.

• Assessing fluid balance during training sessions to help athletes determine individual fluid losses. • Helping athletes prepare a fluid replacement plan for training and competition.

• Incorporating drink opportunities during training.

• Providing cool, flavoured, palatable drinks which are readily accessible during training and competition or establishing team rules designed to encourage fluid intake - i.e. all athletes must bring suitable fluids or a drink bottle to training.

• Allowing athletes to practice and fine tune fluid replacement strategies during training in preparation for competition.

• Periodically monitoring fluid balance to create an awareness of whether athletes are meeting fluid replacement goals.

Hydration

Drink Up!
During training and games, players naturally generate heat leading to a rise in body temperature. A rise in body temperature can be both detrimental to performance but also contribute to fatigue. Our bodies attempt to compensate for rising temperature by sweating. When players do not consume enough fluids during training and games to compensate for these sweat losses, dehydration can quickly occur. As loss as low as 2% of body weight has been shown to affect performance—in a 13.5 stone player, 2% is as little as 3.75lbs. This may not sound much but in a single training session or game a player can easily lose up to 4% of their body weight. Many players do not deal adequately with dehydration, and in fact never fully rehydrate after training or a game. This leads to players taking part in further training sessions already in a dehydrated state exposing themselves to a greater risk of injury. When you are dehydrated, you will feel thirsty, however, thirst is not a good indication of needing to take fluids on board. By the time you feel thirsty you are already dehydrated. Some other symptoms of dehydration include:
There are a number of things that an individual player or the coach of a team can introduce to training and games that will provide a relatively accurate indication of a players hydration status, and how much fluids need to be consumed to get back to normal hydration levels.

Establishing Hydration Status
Knowing how much fluids have been lost is important in rehydrating the body. There are a couple of easy ways of monitoring hydration levels. Known as the WUT method, these tests will provide a simple and accurate method of monitoring hydration status:
W eigh players before and after training and games. Wearing as little clothing as possible — the difference will be weight lost due to sweating.

Use a U rine Colour Chart to monitor the colour of your urine. Generally, the darker the urine, and the less you urinate, the more dehydrated you are.
T hirst — the absence of thirst does not mean that you are not dehydrated.

If you are thirsty, it is likely that you are already slightly dehydrated. Monitoring the colour of urine provides a good indication of being dehydrated. The target is to achieve numbers 1, 2 or 3. Numbers 4 and 5 suggest dehydration, with colours 6, 7 and 8 indicating severe dehydration.

Urine Colour Chart, used to monitor hjydration status

Rehydrating
For each kg of weight lost through sweat replace with 1.5 litres of fluids. Remember that along with water, electrolytes are also lost through sweat — water alone will not replace these electrolytes. Sports drinks contain both carbohydrate for energy and electrolytes. Ensure that your sports drink has a carbohydrate level of 6 — 8%. To help reduce the muscular damage caused by training and games it is best if you consume a source of protein along with your sports drink. Some sports drinks contain a source of protein, however if yours does not, try to consume something light prior to your post-training meal such as a chicken or turkey sandwich. If you do not have access to sports drinks, your post exercise meal can help replace lost electrolytes. An easy way to make your own sports drink is to combine:
200ml of orange squash (concentrated orange)
1 litreof water
A pinch of salt (1g)
Mix all the ingredients together and keep chilled — drinks are absorbed more quickly if they are cool rather than ice cold.

What can a coach do to encourage good hydration habits?
For each game and training session, encourage players to bring their own drinks bottle.
Make time for regular fluid breaks during a training session.
Fluid bottles must be washed out after each use and made up from scratch every day for food safety purposes.
Have a supply of extra fluid bottles in a cooler after training and games.

Combating Dehydration
Monitor hydration status using the WUT Chart above
Aim to drink 2 litres of fluids each day as part of your regular routine
Drink additional fluids before, during and after training and games
Aim to drink 200 - 50ml of fluids 2 hours before a game - remember many referees begin training or games already in a dehydrated state
Try to sip 125 - 250ml evey 15 - 20 minutes to top up fluid levels
Begin to replace any fluids lost during training or a game immediately afterwards by drinking at least 500ml of fluids
Electrolytes, such as sodium or potassium will help rehydration
To completely rehydrate, consume 150% of the amount of fluids lost - for each 1Kg of weight lost, consume 1.5 litres of fluids
Avoid alcohol or caffeine containing drinks until you have completely rehydrated as they can increase urine output

Source -www.medicalwelfare.gaa.ie/drinkuphydrationforplayers.html