Electrolytes are vital substances for the survival of all living creatures, particularly humans. A balance of electrolytes is maintained at normal conditions. This balance is maintained by the movement of water and electrolytes in & out of the cells. There are two oceans of water in the body; one ocean is held inside the cells, and the other ocean is held outside the cells. Good health depends on a most delicate balance between the volume of these oceans, and this balance is achieved by salt. When water is available to get inside the cells freely, it is filtered from the outside salty ocean and injected into the cells that are being overworked despite their water shortage. This is the reason why in severe dehydration we develop an edema and retain water. The design of our bodies is such that the extent of the ocean of water outside the cells is expanded to have the extra water available for filtration and emergency injection into vital cells The brain commands an increase in salt and water retention by the kidneys.
The major electrolytes present within and outside the cell are: Inside the cell: Potassium is present in higher concentration. Outside the cell: Sodium and Chloride are present in higher concentrations.
The main source of sodium is salt. Am average diet contains 8 to 15g of salt. The recommended amount of sodium for adults is 5-15g per day. The main route of excretion of excess sodium is through urine. Much salt is not lost through skin under normal conditions. However, during prolonged strenuous exercise excessive sweat is accompanied by considerable loss of salt with the onset of symptoms like muscle cramps, headache, etc. Professional athletes lose 8g of sodium in perspiration It is important to remember that administration of water alone without addition of salt will bring down the level of sodium and chloride still further and worsen the symptoms.
Vegetables are a good source of potassium The recommended amount of potassium for adults is about 4g/day. Excess potassium is mainly excreted through urine.
Chemical imbalance of the body cannot be taken for granted. Vital functions undergo drastic alterations if electrolyte imbalance is left unattended. Sodium , potassium and chloride are the most important electrolytes present in the body. Concentration of potassium is higher inside the cell. Sodium & chloride are present in higher concentration outside the cell. If a person with healthy kidneys drinks a lot of fluid, they will pass a lot of urine. If the weather is very hot and that person loses a lot of water by sweating, they will not pass so much urine. In this way the kidneys are able to control the body's water content - this is called fluid balance . Acid base balance: The reaction of the blood is slightly alkaline ranging between 7.35 &7.45. If the PH falls below thius the blood becomes acidi , which becomes incompatible for life. Similarly if it goes above 7.5 alkalosis sets in and beyond 7.8 death occurs .Hence it is crucial that PH of blood is maintained nearly constant without undue fall or rise.Electrolytes play an important role in the maintenance of this PH.
60% of the body weight is composed of water. Of this 40% is present inside the cell and 20% is present outside the cell. Water itself regulates the water content of the interior of the cell by working its way into all of the cells it reaches. It has to get there to cleanse and extract the toxic wastes of cell metabolisms. Water regulates body temperature. This is the reason that we sweat more during summer therby keeping the body surface cool than in winter.
The state in which the amount of water leaving the body (in form of urine, faeces, sweat, vomiting, etc) is equal to the fluid entering the body (in form of food, drink, intravenous fluid, etc) is defined as water balance. The total water intake is 2,500 ml and the water output is 2,500 ml under normal conditions. The body responds by increased thirst sensation when the volume of water drops in the body. Similarly when the water volume increases in the body, more water is excreted.
Effective water delivery in nights is mainly because the collected water, that mostly pools in the legs, does not have to fight the force of gravity to get onto the blood circulation.
Module 8 mcc sports nutrition credit course - fluid and electrolyte balance during exercise
Heat Removal• Exercise increases core temperature. For every L of O2 consumed during exercise ~5 kcal is produced but only 1kcal is used for mechanical work – the rest is heat• Increases in core temperature: – Increase blood flow to the skin – Initiate sweating
Sweating and Fluid Loss• Mild to moderate work and routine physical training typically result in whole-body sweat losses of about ~0.8-1.4 L/h.• Evaporation of 1L of water from the skin will remove 573 kcal of heat from the body.• Heat loss via evaporation of sweat is largely dependent on the humidity (proximate to the skin) in which the athlete is working.• Individual sweat rates and fluid losses vary widely between athletes and across sports.
In cool laboratory conditions, VO2max has been shown to decrease with fluid losses > 2% BW... In the heat, sweat rates increase even more such that fluid intake must be even more closely monitored. 100% 80%CapacityExercise 60% 0 1 2 3 4 5 Body weight loss
Effects of dehydration on sportsperformance. % OF BODY WEIGHT PHYSIOLOGICAL EFFECT LOST AS SWEAT 4% CAPACITY FOR MUSCULAR DECREASES 5% HEAT EXHAUSTION 7% HALLUCINATIONS 10% CIRCULATORY COLLAPSE / HEAT STROKES
How does sweating (fluid loss) work to decreaseperformance? increase in plasma osmolarity (higher concentration of solute in solution) release of vasopressin (ADH) from the posterior pituitary gland. ADH causes the kidney to re-absorb water Urine volume goes DOWN dramatically to preserve blood osmolarity, volume and pressure As exercise progresses, the transfer of body water into the plasma cannot keep up with
Daily Water BalanceAthletes need to be fully hydrated before training/competitionThe average sedentary person excretes about2700 milliliters of water/day (1400 from urine, 1100sweat/breath)To replace that 2700 ml, get:• 300-400 ml from metabolism,• 1000 ml from food and• 1300-1400 ml from beverages 2700 ml
Water Output: Normal vs.Exercise50004000 Stool3000 Breath Sweat2000 Urine1000 0 Normal Exercise
Water Intake: Normal vs Exercise500040003000 Metab Food2000 Fluids1000 0 Normal Exercise
In comparison to non-athletes:• Athletes greatly increase their water loss – Large increases in sweat loss – Some decreases in urine loss• Athletes need to greatly increase water intake – Large increases in fluid consumption – Smaller increases in food water and metabolic water – Athletes often fail to consume adequate amounts of fluids to maintain optimal hydration status
Guidelines1. Intake approximately 500ml. (2 cups) of a cool beverage 2 hours before a workout, 250ml (1 cup) in final 15-30 minutes.2. During activity, drink fluid frequently- for example, 150 -200ml(1 cup) every 15-20 minutes.3. After a workout, replenish fluids at a rate of 1litre for every kilogram of body weight lost. Weight should be regained, before the next workout, indicating rehydration.
• Hydrate properly before prolonged exercise in hot environments.• Water is the ideal fluid replacement, although flavored beverages may be more effective at promoting drinking.• The salt in the beverages or as food can promote rehydration more effectively than plain water when significant weight loss has occurred through sweating.• Urine should be pale yellow or clear. This indicates that you are in a hydrated status
Sports DrinksTYPE CONTENTISOTONIC FLUID, ELECTROLYTES , 6-8% CARBOHYDRATEHYPOTONIC FLUID , ELECTROLYTES , LOW CARBOHYDRATEHYPERTONIC HIGH LEVEL OF CARBOHYDRATE
The osmolality of a fluid is a measure of the number of particles in a solution.In a drink, these particles will comprise of carbohydrate, electrolytes, sweeteners and preservatives.In blood plasma the particles will comprise of sodium, proteins and glucose.Blood has an osmolality of 280 to 330mOsm/kg. Drinks with an osmolality of 270 to 330mOsm/kg are said to be in balance with the bodys fluid and are called Isotonic.Hypotonic fluids have fewer particles than blood and Hypertonic have more particles than blood.Consuming fluids with a low osmolality, e.g. water, results in a fall in the blood plasma osmolality and reduces the drive to drink well before sufficient fluid has been consumed to replace losses.
Isotonic - quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes - middle and long distance running or team sports. Glucose is the bodys preferred source of energy therefore it may be appropriate to consume Isotonic drinks where the carbohydrate source is glucose in a concentration of 6% to 8% - e.g. High Five, SiS Go, Boots Isotonic, Lucozade Sport.Hypotonic - quickly replaces fluids lost by sweating. Suitable for athletes who need fluid without the boost of carbohydrate e.g. jockeys and gymnasts.Hypertonic - used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. In ultra distance events, high levels of energy are required and Hypertonic drinks can be taken during exercise to meet the energy demands. If used during exercise Hypertonic drinks need to be used in conjunction with Isotonic drinks to replace fluids.
SALTINSIDE CELL OUTSIDE CELL DEHYDRATION WATER
ELECTROLYTES Electrolytes are electrically charged particles thatconduct electricity as they dissolve in liquids such as water or blood.
SODIUM “ THE YOUTH ELEMENT”• Keeps joints limber• 60% is present in the fluid outside the cell;10% is present inside the cell;30% is present in the bones.• Excessive sweat causes sodium loss as in Hard manual labor Professional athletes Starvation Vomiting & diarrhoea
POTASSIUM “THE ALKALISER”• Makes up 5% of the mineral content of the body.• Plays a vital role in making muscle protein from amino acids.• Concentration of sodium and potassium are inversely proportional to each other.• Dehydration depletes potassium and increase muscle breakdown
FUNCTIONS OF ELECTROLYTES• Regulates water balance• Interacts with the cell membranes to allow nutrients to enter cells and waste to leave• Maintains acid-base balance• Conducts nerve impulse
BODY WATER 60% OF BODY WEIGHT 20% 40% EXTRA INTRA CELLULARCELLULAR
WATER BALANCE Drinking H2O Food stuffs Metabolic & beverages 700 ml water 300ml 1500 ml Body water Urine Feces Skin Lungs1500 ml 150 ml 450 ml 400 ml
INTERESTING FACTS ON WATER• Water delivery inside the cells is more effective in the nights when the body is horizontal• When we drink enough water to pass clear urine, we also pass out a lot of the salt that was held back• Nothing kills life quicker than lack of water• The salinity of the water outside the cells in our bodies is the same as the ocean
Heat and Sweat Production During Exercise• Evaporate 1 liter sweat = 580 Cal heat• 720 Cal heat = evaporates 1.24 liters of sweat• Real conditions, approx. 2 liters
Strategies for Avoiding Dehydration• Establish a hydration protocol for athletes• Determine individual sweat rate – Changes in body weight (pre- post weighings) – 1 kg = 1043ml additional fluids during exercise – May also account for urine volume – Goal: no weight loss (or < 2% wt loss) – Urine color or urine specific gravity
Strategies for Avoiding DehydrationEmphasize continual fluid replacement• Replace fluids as they are lost• Practice fluid replacement – Gradually increase fluids – Body adapts to increase fluid consumption – Generally, cold fluids more rapidly absorbed• Use individual clear bottles for visual monitoring• Old Rule of Thumb: – 0.5-1 cup per 10-15 min – Individualize is far better
Strategies for Avoiding Dehydration• Understand each athlete’s sport dynamics – Rest breaks/time outs – Fluid accessibility• Establish athlete’s acclimatized state – Non-Acclimatized athletes • sweat more • lose more electrolytes
Strategies for Avoiding Dehydration• Anticipate high risk conditions• High temperature – Uniform/clothing effects• High humidity – Indoor sports – Uniform/clothing effects• Low air movement – Uniform/clothing effects• Bright sun – Dark colored clothing
Strategies for Avoiding Dehydration• Hyperhydration – 500 ml, 15-30 minutes prior to exercise – Limited benefits• Post-exercise rehydration – Ideally completed within 2 hrs • ACSM/ADA rec: 700ml per 500gms body weight lost • Replace CHO and electrolytes at same time to speed rehydration
Example:• Joe played tennis for two hours( 120 mins). He drank a 500ml bottle of water during his workout. – Initial weight = 70 – Post-exercise weight = 68• Water loss =70-68 = 2 kgs• % body weight loss = 2/70 = 2.8% (dehydrated)• Total sweat loss = approx 2 litres• To stay hydrated within 2% (minimum fluid replacement rate) – 2% x 70 = 1.4 kgs allowed wt loss = 1.4 litres allowable sweat loss• Maximum fluid replacement rate – 1.4 lits/ 120 min = 11ml/min = 175 ml every 15 min• Recommended fluid replacement (per 15 min) – 2.5-10 oz every 15 min
Sport Drinks Water, CHO, electrolytes replacement during exercise• Provide water• Provide dilute carbohydrates – should be < 10% (<8% optimal) – Gatorade: G+S @ 6% – Powerade: F+GP @ 8% – Fruit juice: F+S @ 11-15% – Soft drinks: F @ 11%
Carbohydrates in Sport Drinks• Glucose – rapidly absorbed and utilized by muscle• Fructose – more slowly absorbed and utilized by liver to replace liver glycogen• Sucrose (G-F)• Glucose Polymers – lower osmolarity than simple sugars and may allow for more rapid water absorption
Sport Drinks• Provide electrolytes during exercise – replace Na and Cl lost in sweat – enhances water uptake • [NaCl] < 1000mg/L – Gatorade: Na,Cl,K,P (460mg/L) – Powerade: (Na,Cl) (300mg/L) – Orange Juice: (10 mg Na/L) – Soft drinks: (40 mg Na/L)
Homemade Sport Drink• lemonade mix(nimbu pani powder)• 1000ml water• ¼ - ½ tsp salt• 6 tablespoon Glucose• 1 tablespoon Sucrose• ½ tbsp baking powder