Water, hydratation and exercise Dehydratation Water and the body fluids n The main roles water in body fluids n Carries nutrients and waste products throughout the body n Maintains the structure of alrge molecules such as proteins and glycogen n Participates in metabolic reactions n Serves as the solvent for minerals, vitamins, aminiacids, glucose, and many other small molecules n Acts as a lubricant nad cushion around joints and inside the eyes, the spinal cord, and, in pregnancy, the amniotic sac surrounding the fetus in the womb n Aids in the regulation of body temperature n Maintains blood volume Distribution of body water Roles of body water n The medium of the body n Homeostasis n Regulation of body temperature n Sweating (convection, conduction, radiation, evaporation (sweat)) n Serve as a key factor in urine formation n Control blood pressure – ADH, aldosterone Water balance Water recommendations n General recommendations for adults n 2 – 3 liter of water (7 – 11 cups) n Good sources of water n Water, fruit juice, fruit and green tea n Bad source of water n Coffee, black tea, alcoholic beverages, nonalcoholic beverages rich in caffeine n Adults 1,0 – 1,5 ml/kcal expended n Infants 1,5 ml/kcal expended Dehydratation Exercise and body water distribution n Increased sweating and breathing => water loss n Reduction of blood volume = a flux of water from plasma into ISF and ICF in active sceletal muscle n Durin ginitial phase of endurance exercise n During strength and power exercise Physiological effects of reduced plasma volume Sweating without water replacement => Reductions in plasma volume => Increased plasma osmolality => Decreased plasma volume => Reduced cardiac output => Decreased blood flow to skin => Decreased sweat production => Increased body core temperature => Fatigue Maintain the blood volume and blood pressure Exercise-induced sweating n The breakdown of energy nutrients => generation of excessive heat => sweating (the primary mechanism for releasing heat) n Sweat rate 1 – 2 l/hour (2 – 3 l/hour) n Higher temperature = ↑ sweating n Sweating of children n Greater ratio of surface than adults n Better nonsweating mechanisms n Lower sweat rate than adults n Adaptation n greater production of volume n Less concentrated sweat solution (↓ sodium, chloride) n Swimming n Heat loss by convection n Lower degree adaptation to sweat loss Estimating sweat loss (A - B) + (C + D) n A = weight before exercise n B = weight after exercise n C = water consumed during exercise n D = water urinated during and after exercise Sweat rate (L/hr or ml/min) = total estimated sweat loss / elapsed time of exercise n Example n A = 84,1 kg, B = 82,7 kg, C = 1 kg (1 l), D = 0,1 kg (100 ml) n (84,1 – 82,7) + (1 + 0,1) = 2,5 kg (2500 ml) n 2,5 L/ 2 hr = 1,25 L/hr = 0,3 L/15 min. n Recommendation: drink 300 ml every 15 minutes Practical guidelines for water consumption n Water consumption before exercise n A day before competition, training and n 2 – 3 hr before training, competition 400 – 600 ml n Experiment with fluid volume and composition n Source of fluid: water, 4 – 8 % carbohydrate drink, electrolyte drink n Carbohydrate – tops up muscle glycogen fuel n Sodium reduces urine losses before exercise n Athletes who train shortly after waking in the morning – drink in the evening and also before training – 500 – 1000 ml 1 hour before Practical guidelines for water consumption n Water consumption during exercise n For longer and more efective training and competition n 150 – 350 ml every 15 – 20 minutes = 600 – 1200 ml/hr n Drrink before you feel thirsty !!! n Composition of sport drink n 6 – 8 % carbohydrate (55 – 80 g carbohydrate/hr.) n Glucose, sucrose, maltodextrines, fructose n Sodium 0,5 – 0,7 g/l – stuimulate absorption of carbohydrate and water Practical guidelines for water consumption n Water consumption after exercise n During trainnig 1 – 2 % reduction of weight n It take several hours to restore body water in all fluid compartments n 500 – 100 ml during first 30 minutes n 1 L every 1 – 2 hours until 150 % of sweat weight loss n Composition n Energy - glucose, sucrose, maltodextrines, fructose n Electrolytes – sodium, potassium Fluids n Sports water n Lightly flavoured with a lower carbohydrate (0 – 4 %) and electrolyte (0 – 12 mg/100 ml) content n For moderate exercise of less than an hour n Sport drinks n Higher amount of carbohydrate (4 – 8 %) and electrolyte (20 – 60 mg/100 ml) n For intensive exercise n For exercise longer than an hour n Water n For low intensity or short duration (less than 45 min.) n Soft drinks, fruit juice n Too high in carbohydrate (8 – 14 %) n Too low in electrolytes (7 – 10 mg/100 ml) n Carbonation – decreses voluntary fluid intake n Energy drinks n Too high carbohydrate (10 – 13 %) n Added ingredients (vitamine, taurine, caffeine