How does water and hydration effect your health and improve performance?
Approximately 40-75% of the Body is Water
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- 2/3 of this Intracellular (Within Cells)
- 1/3 Is Extracellular (Outside Cells)
The Amount of Water We Store Depends:
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- On Our Hydration Status
- On Body Composition
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The More Fat Mass You Have the Less Water You Store.
How Important is water?
Dehydration
- Dehydration Occurs when Fluid Loss is Greater than Fluid Intake such that the Body Becomes Hypohydrated
- Reduced Blood Volume
- Dehydration Causes;
- Reduced Blood Flow to Skin
- Impaired Dissipation of Heat
- Increased Body Temperature
- Strain on Heart
- Increase Exercise RPE
Dehydration and Performance
- Exercising while dehydrate may increase RPE, reduce exercise capacity and reduce intensity and ultimately premature fatigue
- Slight dehydration will not affect performance or physiology
- 2% dehydration may affect performance
- Sports involving decision-making will be affected most
- There is a marked decrease in the ability to perform demanding muscular work at 4% dehydration
- As dehydration progresses, blood becomes thicker due to reduce blood plasma volume and heart rate increases
- Individual responses to dehydration are based on genetics and training status
Rehydration
To aid rehydration and maintain osmotic pressure, fluids containing electrolytes will assist in maintaining plasma volume.
Electrolytes
- Aid Absorption in the Intestine as Opposed to Replenish Losses
- Water Movement Follows Sodium Movement
- Sodium Increases Absorption of Water in Gut to Bloodstream
- Presence of Sodium Promotes Urge to Drink
- Sports Drinks are Isotonic
Isotonic Drinks
- “Isotonic” drinks mean the fluid has the same osmolality as the body
- Characteristics of Isotonic Drinks:
- Same Osmolality as the Plasma
- 4-9 g/100ml Carbohydrates
- Faster Absorption from the Gut Vs Water
- Quicker Rehydration Vs Water
- Useful Energy Source
Drink Hydration Matrix
- The beverage hydration index gives a comparison of the rehydration potential of various drinks
- The drinks included in the study were compared to the rehydration potential of water
- Contrary to popular belief beer, coffee and tea had similar rehydration potential to water
Hydration Guidelines
- The duration of exercise and the amount of fluid loss will determine the type of solution to use
- In general, water is a good rehydration solution as the sodium lost during exercise can be made up throughout the day through food/drink
- The use of sports/carbohydrate replacement drinks will come down to:
- Intensity/Duration of Exercise
- Personal Preference
- Post Exercise Hunger Levels
- Food Choices After Exercise
Summary
- The body must balance an increase in heat production during exercise with heat loss to maintain exercise intensity
- Many intrinsic and extrinsic factors influence sweat rates
- Duration, intensity of exercise and environmental factors influence sweat rates
- Dehydration Likely Impairs Performance
- Monitor Hydration Status
- Always Start Exercise in a Hydrated State
- Water + Normal meals & snacks may be sufficient to restore the body to rehydration
- Sports +/- carbohydrate drinks are a useful tool for those exercising >90 minutes