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HYDRATION

“HYDRATION” Key for maintaining complete health and achieving ideal workout performance.

Avg. Body Mass = 60-70 % water

Can dramatically during extraneous activity.

∴ Maintenance of fluid uptake is EXTREMELY IMPORTANT

65% ICF (intracellular fluid) 35% ECF (extracellular fluid) 25% tissue (interstitial) fluid 8% blood plasma & lymph 2% transcellular fluid

Ingested water water absorbed by small intestine passed through the bloodstream continually changing between chief fluid compartments

WATER ABSORPTION

Water transportation through intestinal mucosa- osmosis process:

Initiates at digestive tract through lumen into the bloodstream.

All regions in the intestine absorb water; however uptake differs in each region, depending on solute presence.

Jejunum: Active transport of sugars and amino acids cause transport of salt and water maximum water uptake.

Ilium: Active sodium transport is the main cause of water movement.

Lumen: Capillary filtration interchanges the water from blood into tissue fluid, where eventually it is absorbed by the ICF compartment.

During rest and exercise, water moves freely through plasma membranes where compartment gradients can easily alter

If tissue fluid osmolality increases, water moves out of cells. When fluid osmolality decreases, water moves inside cells.

Maintenance of electrolyte osmolality within fluid compartments is dependant on their solute concentration.

* A vital pathway for athletes

Intracellular (inside cells)

Extracellular (outside cells)

Membranes of most cells contain pumps that aid in:

- sodium removal from cells into lateral spaces - transfer potassium inside the cells

Involves use of energy (ATP), so if energy is not accessible, sodium remains in the cells and builds up.

“Sodium-potassium ATPase-pump”

Highly Depends On

Genetics, body size, fitness level, environment and intensity of exercise --- (INDIVIDUALISED)

Up to 1.5L of water can be lost during every hour of exercise, therefore must be replaced to prevent possible decrease in the athlete’s body temperature or blood volume ‘Dehydration’

HOW MUCH FLUID IS ENOUGH?

BEFORE: Constant fluid intake leading up to training/competition, ensuring all meals and snacks are accompanied with fluid (200-600ml).

DURING: Prepare to drink early in the exercise, & continue with small amounts throughout

(200-300ml every 15 minutes)

POST: (300-600ml straight after) - Sweat and urinary losses continue for 4-6 hours after, so keep hydrating during these crucial periods.

If lost at an rate, certain sodium/potassium requirements are vital in the rehydration process.

(sport drinks, oral supplements, and or foods high in salt)

WATER AVAILABILITY is crucial and also a vital element of plasma--- essential in the maintenance of blood volume (BV).

If BV is hindered, function of the circulatory system can be modified, causing a delay in an athlete’s performance.

During exercise, the nature and intensity defines the amount and frequency of water movement between fluid partitions.

The aim of fluid intake is to replace losses and maintain fluid and electrolyte balance.

Thus allowing for normal cell and organ function.

If outputs are not replaced, a negative state of fluid balance can be a fatal consequence…

DEHYDRATION

During exercise, fluid is lost through the by-product of ENERGY PRODUCTION, where ‘heat’ is shifted from the athlete’s body to the environment --- known as ‘SWEATING’.

THE ATHLETE SIMPLY SWEATS TO RID OF THE EXCESS HEAT PRODUCED.

DEHYDRATION can come about due to body water loss prior to or during exercise...

THROUGH---- Faeces or urine - Sweat- Exhaled breath

EFFECTS

Decreased Blood Volume

Decreased Skin Blood Flow

Decreased Sweat Rate

Increased Core Temperature

Increased Muscle Glycogen Use

The amount of sweat loss, determines the volume of fluid transported between intracellular space to the interstitial and plasma regions.

Performance & training ability becomes diminished and prevention of thermoregulation can arise with any dehydration level…

Only a 2% loss of water in our body weight whilst performing exercise in a hot or humid climate CAN result in

DEHYDRATION.

+++ minerals/salts, found in our blood and other fluid compartments.

Electrolytes determine our; body water, blood pH & muscle function

Through extreme perspiration, electrolytes are lost, thus must be replaced with supplements, e.g. fluids, tablets or powders.

Our Bodies use; sodium, potassium, chloride, calcium & magnesium.

Why? … to function properly …

--- Body cells (nerves, heart, muscle) use them for maintenance across the cell membrane & to transport electrical impulses, (e.g. muscle contractions & nerve impulses).

ELECTROLYTES

With Ultra-endurance activity, fluids containing electrolytes and CHO can become vital in overall performance and energy output.

*** 2-3L/hr. can be lost about 10-14 grams of sodium.

Thus… rehydration is the key.

FLUIDS: ELECTROLYT

ES & CHO

Sodium Essential electrolyte for prevention of muscle weakness Needed during exercise where dehydration causes a drop in blood plasma

volume, thus sodium helps increase the blood plasma value

An electrolyte added to sports drinks to replace ‘lost salts’ through sweat and to stimulate glucose and water uptake in the small intestine --- ensures optimal maintenance in the ECF.

Normal Sodium levels in the blood plasma= 136-145mmol/L

Potassium - vital for growth- muscle re-build- nerve impulse transmission - aids in heart activity- prevent fatigue, cramps & muscle

weakness

Together, potassium inside the cell and sodium outside the surrounding cells, help convey communication

from the nervous system and ensure muscle contraction regulation.

In addition, magnesium is another electrolyte that can aid

in post exercise recovery, in particular muscle relaxation,

through minimising cramps and twitching.

CHO main fuel for optimal muscle function.

Failing to replenish carbohydrate stores before, during & after exercise, particularly with ultra-endurance activities, the body will shut down.

--- Our bodies begin to use extra effort to break down & use other fuel stores, which is not ideal.

General Rule: >90 minutes of activity 30-60g carbohydrates/hourMaintain stores & prevent depletion

However… dependant on the athletes - sweat rates- digestive tolerance- climate- duration and intensity of exercise

Sports drinks, powders & gels are ideal methods of maintaining & re-fuelling an athlete’s

- Blood glucose levels

- Fluid

- Electrolytes

- Working muscles

IMPORTANT…

Certain CHO & electrolyte supplements are required mainly to athletes competing or training in events >1-2 hours

UNLESS the intensity is extremely high or the individual feels as though they are running low on fuel & perspiration is shown in large amounts.

‘Conditions, consulting a disturbance in ones water balance’

HYPERNATREMIA = high sodium in blood plasma, relative to water concentration

HYPONATREMIA= low sodium in blood plasma, relative to water concentration

HYPERNATREMIA

Insufficient water in the body with plasma sodium >145mmol/L in the ECF (>155mmol/L is life threatening)

Causes- water loss in relation to sodium volume in the body due to;- inadequate access to water- free water loss (renal or extrarenal)- prohibited sense of thirst

An ‘antidiuretic hormone’ (ADH)/vasopressin is released in response to low BP and low salt in water concentration, to instruct kidneys in conserving water and help stimulate thirst. If compromised, reabsorption of water and sense of thirst is prohibited, causing an imbalance of sodium, thus hypernatremia arises.

HYPONATREMIA(OVER-HYDRATION)

How it occurs?Excess fluid and insufficient sodium is not ingested during prolonged exercise, causing the extracellular fluid to become “hypotonic”

During sustained exercise, extreme perspiration escalates the athlete’s possibility in sodium deficiency in the blood stream.

When athlete replaces losses with plain water, without electrolytes, dilution in the ECF occurs, triggering quick onset of ‘severe hyponatremia’ (Na+, <120meq/l), resulting in development of neurological symptoms, such as brain swelling.

Furthermore… OVER-CONSUMPTION OF WATER

The body is efficient in maintaining fluid and electrolyte balance.Kidneys--- active at managing unnecessary water inside the body, through urine excretion; however when a person consumes a lot of water in a given time, the kidneys are unable to excrete fast enough or when the body is under physical stress, increased secretion of hormone ‘aldosterone’ (vasopressin) triggers the kidneys to ‘conserve’ water, thus water builds up in the blood--- causing water to move into cells and swell as a way of accommodating.

However, this build-up causes the water to enter the brain. Inside the brain is only minimal space with packed cells, & when water enters, there is no room for cells to expand. As a result brain swelling occurs, following seizures, coma and eventually death if the victim is not attended to immediately (>48hrs).

--- Prompt administration of hypertonic saline (salt) solution is required and water must be constrained.https://www.youtube.com/watch?v=t1nwSuWr_q8

--- A healthy kidney can excrete up to 800-1000ml/hour, so drinking this amount per hour cannot harm.

--- Except when our bodies undergo physical stress, such as marathon runners. This stress increases ‘vasopressin’ excretion.Vasopressin --- produced by the hypothalamus into the bloodstream to communicate

with kidneys to “preserve water”.

** Thus, the kidney reduces excretion to no >100ml/hour, causing build-up of water in the bloodstream.

Those mainly at risk

Higher prevalence in inexperienced individuals competing in high endurance fundraising events, exceeding 4 hours thus have more time to continuously drink & place increase strain on their bodies.

REMEMBER!

High intensity, endurance activities, >3 hours

Obtaining enough sodium, before, during & post, partnered with high water intake is vital. Particularly

during hot/humid climates.

However! Don’t forget! Activity <1 hour Fuel your body with plain water, & natural sugar, CHO substitutes like fresh fruit during or after trainings/games. Post trainings, opt for natural sodium in foods like certain veggies and eggs. These options will benefit your body without adding any nasty or additional salts and sugars.

Additionally, athletes need to be aware of misleading guidelines of “drinking as much as they can”, as it is dependent on the type of

athlete, their intensity, duration & present temperature.

INDIVIDUALISE YOUR OWN WATER AND

ELECTROLYTE INTAKE!

AIMEE CECILYSTAY HYDRATED!

Agarwal, M, Agrawal, V, Ghosh, AK, Joshi, S 2008, ‘Hyponatremia and Hypernatremia: Disorders of Water Balance’, Department of Internal Medicine, viewed 5 April 2014, <http://www.japi.org/december_2008/R-1.html>

Australian Institute of Sport 2011, Electrolyte replacement supplements: AIS Website Fact Sheet – AIS Sports Supplementation Program, viewed 10 April 2014, <http://www.ausport.gov.au/__data/assets/pdf_file/0011/463538/Electrolyte_replacement_11-_website_fact_sheet.pdf>

Australian Institute of Sport 2014, Fluid - Who Needs It, Australian Government: Australian Sports Commission, viewed 10 April 2014, <http://www.ausport.gov.au/ais/nutrition/factsheets/hydration/fluid_-_who_needs_it>

Ballantyne, C 2007, ‘Strange but true: drinking too much water can kill’, Scientific American, 21 June, viewed 18 April 2014, <http://www.scientificamerican.com/article/strange-but-true-drinking-too-much-water-can-kill/>

REFERENCES

Driskell, J, Wolinsky, I 2008, Sports Nutrition: Energy metabolism & Exercise, Taylor & Francis Group, Boca Raton, FL, viewed 30 March 2014, CRC Press. http://faculty.mu.edu.sa/public/uploads/1348479767.566sports%20nutrition.pdf

Dugdale, D 2014, ‘Hyponatremia: Symptoms’, Medline Plus, 26 February, viewed 24 April 2014, <http://www.nlm.nih.gov/medlineplus/ency/article/000394.htm>

Ellert, M 1998, Nutrient Absorption: Water, GI 4.2 Study Guide, viewed 28 March 2014, <http://www.siumed.edu/mrc/research/nutrient/gi42sg.html?>

Elsevier Health 2012, Hypernatremia: background; description, Clinical Key, viewed 3 April 2014, https://www.clinicalkey.com.au/topics/nephrology/hypernatremia.html

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Guest, N 2014 Hypernatremia or Over Hydration- whose at risk, SportMed.BC, viewed 5 April 2014, < http://sportmedbc.com/article/hyponatremia-or-overhydration%E2%80%94who-risk>

Helmenstine, A 2014 Can you drink too much water, About.com Chemistry, viewed 3 April 2014, <http://chemistry.about.com/cs/5/f/blwaterintox.htm>

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Kravitz, L 2007, ‘Water: The Science of Nature's Most Important Nutrient’, The University of New Mexico, viewed 28 March 2014, http://www.unm.edu/~lkravitz/Article%20folder/WaterUNM.html

Kirven, J, Rosner, M 2014, ‘Exercise-Associated Hyponatremia’, Clinical Journal of the American Society of Nephrology, vol. 2, no. 1, pp. 151-161.

Mann, J, Truswell, A 2012, ‘Water, electrolytes and acid-base balance’, in 3 (ed.), Essentials of Human Nutrition, Oxford University Press, New York, pp. 125-133.

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