None “My biggest weakness as an endurance athlete has been in not drinking enough water after training, thereby racing sometimes while dehydrated.” Bill Rodgers There is a wealth of evidence out there which has long ago proved that regular ingestion of fluids is essential for sporting performance. We hear this all the time but let’s now focus on why this is so.
In one study, runners preformed a 5k and a10 k run in either a normally hydrated or in a slightly dehydrated state. It was found that when hydration dropped by 2% their running speed dropped substantially in both events (by 6-7%)
Dehydration impairs the body’s ability to regulate heat, this results in increased body temperature and increased heart rate, causing extra strain on the heart, lungs and circulatory system making exercise harder and causing early fatigue. Aerobic capacity falls by 10-20% with equivalent 10-20% deterioration in performance. Also perceived exertion is increased causing the athlete to feel more fatigued than usual at a given work rate. Mental function is reduced effecting concentration levels and decision making ability. Gastric emptying is slowed causing stomach upset and discomfort. Have you ever felt this way?
These effects have been detected when fluid deficits are just 2% (that is a deficit of 1.2 litres in a 60 kg athlete)
So why do you become dehydrated? Whenever you exercise you lose fluid primarily through sweating. When muscles start to exercise they produce extra heat, in fact 75% of the energy put into exercise is actually converted to heat and lost….this is why we feel warmer when exercising. In order to keep the core body temperature stable this heat is dispersed by warm body water moving to the skins surface where it evaporates. Thereby losing the heat produced…but also the body’s water.
The replacement of this fluid is essential when training regularly and competing. During 1 hours exercise the average person could expect to lose around 1 litre of fluid but if the weather is hot this could increase to 2 litre/hr.
The feeling of thirst is a very poor indicator of hydration status; infact if you feel thirsty you have already lost 1.5-2 litres and are significantly dehydrated. Equally if you find water or sports drink hard to tolerate while running it may be because you are already dehydrated. Other signs include general sense of fatigue, headaches, loss of appetite, feeling excessively hot, lightheadedness and nausea. Ironically the more dehydrated you become the less you sweat so this is not a good indication either. Also remember that fitter people sweat earlier and in larger volumes, as your fitness improves you fluid requirement will increase.
The PEE test, looking at the colour of urine after exercise is a surprisingly accurate way of detecting dehydration. Urine described as ‘very pale yellow’ indicates that you are within 1% of optimal hydration, any darker you need to reassess your hydration strategies.
Fluid requirements vary remarkable between athletes and exercise situations. Athletes can easily estimate their own fluid requirements by weighing themselves before and after a session in the same clothing after towel dry. Each kg lost is equivalent to 1 litre of fluid, adding in any fluid taken in during the session gives an accurate measure of fluid requirements.
Case Study: an athlete who finishes an exercise session 1 kg lighter and who has consumes 1 litre of fluid during the session has a total fluid loss of 2 litres.
In this situation advice would be:
Over following 2-4 hrs replace 1.5 times Body weight loss = 1.5l
Then: increase amount in next training session to 2 litres.
So knowing why it is important to drink and how to estimate your own fluid requirements we will now consider what to drink?
The Great Debate – Water or Sport drinks?
Not to get to complicated we will simply focus on the what the body needs;
• Fluid – To prevent dehydration and enhance performance
• Sodium – To replace salt lost in sweat, prevent cramping
• Carbohydrate – To fuel working muscles, delay fatigue
For sessions of 60 minutes or more in duration the body will need these three criteria to perform well.
Water does quench thirst, indeed this is one of its failings; the sensation of water in the mouth switches off thirst indicators in the brain, therefore when drinking water, athletes are inclined to drink less that the body actually needs. Therefore water drinkers need to ensure they drink according to their requirements not their thirst.
However a simple solution to this problem is the addition of sodium. Athletes who take small amounts of sodium in the fluid not only replace salt lost in sweat but also drink more. Carbohydrate provides energy for working muscles but also speeds up gastric emptying thereby reducing any stomach upset and speeding up absorption of fluid. Carbohydrate also gives the fluid a nice taste thereby enabling the athlete to drink more.
The benefits of Sports Drinks are that the fluid, sodium and carbohydrate are in the quantities required for peak absorption and performance, the taste encourages the athlete to drink more and the packaging is conducive to drinking while running. Normal soft drinks and squashes are too high in carbohydrate, requiring body water for digestion and can therefore contribute to dehydration rather than alleviate it and many don’t have enough sodium. Carbonated drinks have also been shown to contribute to heartburn and stomach discomfort.
However this does not mean commercial sports drinks are the only solution. Homemade solutions are much more effective than either water or soft drinks. The ingredients are listed below.
200ml Fruit Squash
800ml Water
¼ tsp salt
500ml Fruit Juice
500ml Water
¼ tsp salt
These recipes are for isotonic drinks which provide the ideal compromise between rehydration and refueling.
The isotonic nature of the drinks mean that when taken in small volumes regularly throughout a sessions there is no resulting need to go to the bathroom.
General Fluid recommendations for Race Day are:
• Well hydrated from previous few days increased fluid intake
• 300 – 600ml with pre-event meal
• 150ml-300ml every 15-20 mins until 45 min before event
• 300-400ml immediately before – need to trial in training
• 150ml every 15-20 minutes during event – match sweat losses
The more you drink in training the more you will tolerate and this will pay off in longer distance events. We can learn over a number of weeks to increase our tolerance for fluid through starting with 100ml every 15 minutes and building over a number of months. The use of race belts with bottles, camelbacks and running bottles are encouraged for training to simulate water stops in events. For ultra endurance training, preplanning the training route and placing fluids along this is encouraged.
I hope this has encouraged readers to increase their intake of fluid when training and competing.
I will leave the final word to Homer Simpson, expert on nutrition and hydration…
“Son, when you participate in sporting events, it’s not whether you win or lose, it’s how drunk you get.”
Ruth Kilcawley
BSc. Human Nutrition & Dietetics
SNIG MINDI
There is a wealth of evidence out there which has long ago proved that regular ingestion of fluids is essential for sporting performance. We hear this all the time but let’s now focus on why this is so.
In one study, runners preformed a 5k and a10 k run in either a normally hydrated or in a slightly dehydrated state. It was found that when hydration dropped by 2% their running speed dropped substantially in both events (by 6-7%)
Dehydration impairs the body’s ability to regulate heat, this results in increased body temperature and increased heart rate, causing extra strain on the heart, lungs and circulatory system making exercise harder and causing early fatigue. Aerobic capacity falls by 10-20% with equivalent 10-20% deterioration in performance. Also perceived exertion is increased causing the athlete to feel more fatigued than usual at a given work rate. Mental function is reduced effecting concentration levels and decision making ability. Gastric emptying is slowed causing stomach upset and discomfort. Have you ever felt this way?
These effects have been detected when fluid deficits are just 2% (that is a deficit of 1.2 litres in a 60 kg athlete)
So why do you become dehydrated? Whenever you exercise you lose fluid primarily through sweating. When muscles start to exercise they produce extra heat, in fact 75% of the energy put into exercise is actually converted to heat and lost….this is why we feel warmer when exercising. In order to keep the core body temperature stable this heat is dispersed by warm body water moving to the skins surface where it evaporates. Thereby losing the heat produced…but also the body’s water.
The replacement of this fluid is essential when training regularly and competing. During 1 hours exercise the average person could expect to lose around 1 litre of fluid but if the weather is hot this could increase to 2 litre/hr.
The feeling of thirst is a very poor indicator of hydration status; infact if you feel thirsty you have already lost 1.5-2 litres and are significantly dehydrated. Equally if you find water or sports drink hard to tolerate while running it may be because you are already dehydrated. Other signs include general sense of fatigue, headaches, loss of appetite, feeling excessively hot, lightheadedness and nausea. Ironically the more dehydrated you become the less you sweat so this is not a good indication either. Also remember that fitter people sweat earlier and in larger volumes, as your fitness improves you fluid requirement will increase.
The PEE test, looking at the colour of urine after exercise is a surprisingly accurate way of detecting dehydration. Urine described as ‘very pale yellow’ indicates that you are within 1% of optimal hydration, any darker you need to reassess your hydration strategies.
Fluid requirements vary remarkable between athletes and exercise situations. Athletes can easily estimate their own fluid requirements by weighing themselves before and after a session in the same clothing after towel dry. Each kg lost is equivalent to 1 litre of fluid, adding in any fluid taken in during the session gives an accurate measure of fluid requirements.
Case Study: an athlete who finishes an exercise session 1 kg lighter and who has consumes 1 litre of fluid during the session has a total fluid loss of 2 litres.
In this situation advice would be:
Over following 2-4 hrs replace 1.5 times Body weight loss = 1.5l
Then: increase amount in next training session to 2 litres.
So knowing why it is important to drink and how to estimate your own fluid requirements we will now consider what to drink?
The Great Debate – Water or Sport drinks?
Not to get to complicated we will simply focus on the what the body needs;
• Fluid – To prevent dehydration and enhance performance
• Sodium – To replace salt lost in sweat, prevent cramping
• Carbohydrate – To fuel working muscles, delay fatigue
For sessions of 60 minutes or more in duration the body will need these three criteria to perform well.
Water does quench thirst, indeed this is one of its failings; the sensation of water in the mouth switches off thirst indicators in the brain, therefore when drinking water, athletes are inclined to drink less that the body actually needs. Therefore water drinkers need to ensure they drink according to their requirements not their thirst.
However a simple solution to this problem is the addition of sodium. Athletes who take small amounts of sodium in the fluid not only replace salt lost in sweat but also drink more. Carbohydrate provides energy for working muscles but also speeds up gastric emptying thereby reducing any stomach upset and speeding up absorption of fluid. Carbohydrate also gives the fluid a nice taste thereby enabling the athlete to drink more.
The benefits of Sports Drinks are that the fluid, sodium and carbohydrate are in the quantities required for peak absorption and performance, the taste encourages the athlete to drink more and the packaging is conducive to drinking while running. Normal soft drinks and squashes are too high in carbohydrate, requiring body water for digestion and can therefore contribute to dehydration rather than alleviate it and many don’t have enough sodium. Carbonated drinks have also been shown to contribute to heartburn and stomach discomfort.
However this does not mean commercial sports drinks are the only solution. Homemade solutions are much more effective than either water or soft drinks. The ingredients are listed below.
200ml Fruit Squash
800ml Water
¼ tsp salt
500ml Fruit Juice
500ml Water
¼ tsp salt
These recipes are for isotonic drinks which provide the ideal compromise between rehydration and refueling.
The isotonic nature of the drinks mean that when taken in small volumes regularly throughout a sessions there is no resulting need to go to the bathroom.
General Fluid recommendations for Race Day are:
• Well hydrated from previous few days increased fluid intake
• 300 – 600ml with pre-event meal
• 150ml-300ml every 15-20 mins until 45 min before event
• 300-400ml immediately before – need to trial in training
• 150ml every 15-20 minutes during event – match sweat losses
The more you drink in training the more you will tolerate and this will pay off in longer distance events. We can learn over a number of weeks to increase our tolerance for fluid through starting with 100ml every 15 minutes and building over a number of months. The use of race belts with bottles, camelbacks and running bottles are encouraged for training to simulate water stops in events. For ultra endurance training, preplanning the training route and placing fluids along this is encouraged.
I hope this has encouraged readers to increase their intake of fluid when training and competing.
I will leave the final word to Homer Simpson, expert on nutrition and hydration…
“Son, when you participate in sporting events, it’s not whether you win or lose, it’s how drunk you get.”
Ruth Kilcawley
BSc. Human Nutrition & Dietetics
SNIG MINDI
