Hydration and Fluid Hydration and Fluid ReplacementReplacement

By Michael BransfieldBy Michael Bransfield

Hydration and Fluid Hydration and Fluid ReplacementReplacement

• Fluid in take is the most important nutritional factor during competition . Fluid in take is the most important nutritional factor during competition . Dehydration is a concern during any physical activity. Athletes should Dehydration is a concern during any physical activity. Athletes should aim to drink regularly rather then wait until they become thirsty as thirst aim to drink regularly rather then wait until they become thirsty as thirst is often a poor indicator of hydration.is often a poor indicator of hydration.

• Fluid requirements vary remarkably between athletes and between Fluid requirements vary remarkably between athletes and between exercise situations.  Fluid losses and the onset of dehydration are affected exercise situations.  Fluid losses and the onset of dehydration are affected by:by:– Genetics - some people innately sweat more than othersGenetics - some people innately sweat more than others– Body Size - larger athletes tend to sweat more than smaller athletesBody Size - larger athletes tend to sweat more than smaller athletes– Fitness - fitter people sweat earlier in exercise and in larger volumesFitness - fitter people sweat earlier in exercise and in larger volumes– Environment - sweat losses are higher in hot, humid conditionsEnvironment - sweat losses are higher in hot, humid conditions– Exercise Intensity - sweat losses increase as exercise intensity increasesExercise Intensity - sweat losses increase as exercise intensity increases

• Generally athletes should aim to drink 150- 250mls of water every 15 Generally athletes should aim to drink 150- 250mls of water every 15 minutesminutes

Fluid Losses Fluid Losses

From the pictures above it can be seen that in normal everyday conditions water input vs. output is balanced. However during heavy exercise the amount of fluid lost as sweat increases greatly meaning that a larger quantity or fluid most be consumed to recreate a balance.www.extension.iastate.edu/nutrition/sport/images/02.011A.jpg&imgrefur

General Fluid Replacement General Fluid Replacement GuidelinesGuidelines

• Immediately, before exercise commences, consume 200-600 ml of fluid.Immediately, before exercise commences, consume 200-600 ml of fluid.

• Develop a plan for fluid intake for all exercise sessions longer than 30 Develop a plan for fluid intake for all exercise sessions longer than 30 minutes. Aim to match previous fluid losses as closely as possible minutes. Aim to match previous fluid losses as closely as possible (within 1% of body mass). Take into account all the opportunities (within 1% of body mass). Take into account all the opportunities within the sport.within the sport.

• Begin drinking early in the exercise session and continue to drink Begin drinking early in the exercise session and continue to drink small amounts regularly.  Sports drink or water are the best options.small amounts regularly.  Sports drink or water are the best options.

• Aim to replace fluids as they are lostAim to replace fluids as they are lost

((http://www.ausport.gov.au/ais/nutrition/factsheets/hydration2/fluid_-_who_needs_ithttp://www.ausport.gov.au/ais/nutrition/factsheets/hydration2/fluid_-_who_needs_it))

General Fluid Replacement General Fluid Replacement Guidelines cont.Guidelines cont.

• Drink plenty of water after exercise, past the point of quenching your Drink plenty of water after exercise, past the point of quenching your thirstthirst

• Avoid drinking tea, coffee, cola drinks and alcohol after training or Avoid drinking tea, coffee, cola drinks and alcohol after training or gamesgames

• Glucose are not recommended as they can speed up the onset of Glucose are not recommended as they can speed up the onset of dehydrationdehydration

• Sports drinks should only be taken in small amounts before a sport to Sports drinks should only be taken in small amounts before a sport to prevent the early use of glycogen storesprevent the early use of glycogen stores

In events of less then 30 In events of less then 30 minsmins

• Hydrate well before the eventHydrate well before the event• Fluid taken during the event will not benefit performance as it will not Fluid taken during the event will not benefit performance as it will not

become available to the body within 30 minutesbecome available to the body within 30 minutes• Fluid taken during the event will alleviate a dry mouth and improve Fluid taken during the event will alleviate a dry mouth and improve

perceived exertionperceived exertion

In events of 30- 60 mins In events of 30- 60 mins

• Begin the event well hydratedBegin the event well hydrated• As a general rule replace fluid every 15 minutes by drinking 150- As a general rule replace fluid every 15 minutes by drinking 150-

250mls of water250mls of water• A supplementary source of carbohydrate during exercise has been A supplementary source of carbohydrate during exercise has been

shown to improve performance in some events as short as 60 minutes. shown to improve performance in some events as short as 60 minutes. A general recommendation is 30- 60 grams of carbohydrate per hour. A general recommendation is 30- 60 grams of carbohydrate per hour. The average sports drink contains 60- 80 grams per liter so an athlete The average sports drink contains 60- 80 grams per liter so an athlete should use a diluted sports drink approximately one third sports drink should use a diluted sports drink approximately one third sports drink and two parts waterand two parts water

In endurance eventsIn endurance events

• Begin the event well hydratedBegin the event well hydrated• Replace fluid regularlyReplace fluid regularly• Consume 30- 60grams of carbohydrate per hour of exercise, these Consume 30- 60grams of carbohydrate per hour of exercise, these

carbohydrates can be obtained from sports drinks.carbohydrates can be obtained from sports drinks.• Avoid carbohydrates that delay the stomach emptying(e.g. Avoid carbohydrates that delay the stomach emptying(e.g.

carbohydrate foods that are high in fat or fibre), or cause carbohydrate foods that are high in fat or fibre), or cause gastrointestinal problems. Good sources of carbohydrate are jam gastrointestinal problems. Good sources of carbohydrate are jam sandwiches, bananas, thick sugary syrups, muesli bars, jelly beans, sandwiches, bananas, thick sugary syrups, muesli bars, jelly beans, cordial or other sports drinkscordial or other sports drinks

DehydrationDehydration

• It has been demonstrated that dehydration of just 1-2% of body weight can alter It has been demonstrated that dehydration of just 1-2% of body weight can alter physiological function and negatively influence an athlete’s performance.  The signs of physiological function and negatively influence an athlete’s performance.  The signs of dehydration start just one hour or sooner of exercise.  It is a risk factor for athletes dehydration start just one hour or sooner of exercise.  It is a risk factor for athletes developing heat cramps, heat exhaustion, and the potentially life-threatening heat strokedeveloping heat cramps, heat exhaustion, and the potentially life-threatening heat stroke

• Dehydration can be prevented by drinking fluids regularly Dehydration can be prevented by drinking fluids regularly • Signs and symptoms of dehydration include:Signs and symptoms of dehydration include:

– Thirst Thirst – Irritability     Irritability     – Cramps    Cramps    – Headache Headache – NauseaNausea– VomitingVomiting– WeaknessWeakness– Head or neck heat sensationsHead or neck heat sensations– DizzinessDizziness– Decreased performanceDecreased performance((

http://www.csmfoundation.org/James_Madison_Univ. Fluid_Replacement_Guidelines_and_Exertional_Heat_Illnesseshttp://www.csmfoundation.org/James_Madison_Univ. Fluid_Replacement_Guidelines_and_Exertional_Heat_Illnesses.doc.doc))

Sports DrinksSports Drinks

• Sports drinks are an ideal fluid to consume during and after training and Sports drinks are an ideal fluid to consume during and after training and competition sessions, allowing the athlete to replace fluid and electrolyte losses, competition sessions, allowing the athlete to replace fluid and electrolyte losses, and simultaneously providing an additional source of carbohydrate fuel. In and simultaneously providing an additional source of carbohydrate fuel. In many situations, sports drinks are a better choice than water because:many situations, sports drinks are a better choice than water because:– They are likely to promote better fluid intake than water. They are likely to promote better fluid intake than water. – They provide an additional source of fuel that may enhance performance They provide an additional source of fuel that may enhance performance

and reduce immune stresses. and reduce immune stresses. – In situations in which these benefits do not occur, sports drinks do not In situations in which these benefits do not occur, sports drinks do not

detract from performance compared to water. detract from performance compared to water. • Powdered sports drinks can be made up in different concentrations to change Powdered sports drinks can be made up in different concentrations to change

the relative delivery of fluid and carbohydrate. For example, a more the relative delivery of fluid and carbohydrate. For example, a more concentrated drink may be useful when intake of fuel has priority over concentrated drink may be useful when intake of fuel has priority over hydration (e.g. exercise in a cold environment when sweat losses are small), and hydration (e.g. exercise in a cold environment when sweat losses are small), and a more dilute drink may be useful when fluid replacement is critical.. a more dilute drink may be useful when fluid replacement is critical.. Alterations to the standard formulation will change the taste profile and may Alterations to the standard formulation will change the taste profile and may reduce voluntary intake of the sports drink. reduce voluntary intake of the sports drink.

• http://www.ausport.gov.au/ais/nutrition/supplements/resources/supplement_fact_sheets/sports_dhttp://www.ausport.gov.au/ais/nutrition/supplements/resources/supplement_fact_sheets/sports_drinksrinks

AnswersAnswers

• Q1. Q1. Dehydration which is affected by genetics, body size, fitness, Dehydration which is affected by genetics, body size, fitness, environment and exercise intensity.environment and exercise intensity.

• Q2. Q2. Replace fluid as they are lost, drink plenty after exercise past Replace fluid as they are lost, drink plenty after exercise past point of quenching thirst, 200- 600mls before exercise commencespoint of quenching thirst, 200- 600mls before exercise commences

• Q3. Q3. Because it does not become available to the body in that amount of Because it does not become available to the body in that amount of timetime

• Q4. Q4. Replace fluid every 15 minutes by drinking 150- 250mls of water Replace fluid every 15 minutes by drinking 150- 250mls of water during eventduring event

• Q5. Q5. Fluid loss greater then 1% - 2% of total body weight, Thirst Fluid loss greater then 1% - 2% of total body weight, Thirst Irritability, Cramps, Headache, Nausea, Vomiting, Weakness, Head or Irritability, Cramps, Headache, Nausea, Vomiting, Weakness, Head or neck heat sensations, Dizziness and Decreased performance are the neck heat sensations, Dizziness and Decreased performance are the symptomssymptoms

• Q6. Q6. They are likely to promote better fluid intake than water.They are likely to promote better fluid intake than water.