Fluid And Exercise PDF

FLUID AND EXERCISE  Water (H2O) in your body contains numerous mineral – electrolytes H2O makes up between 50 – 75% of your weight Water for Leaner > H2O (obese – 40%, muscular – 70%) – protein contains more water than Life...

FLUID AND EXERCISE  Water (H2O) in your body contains numerous mineral – electrolytes H2O makes up between 50 – 75% of your weight Water for Leaner > H2O (obese – 40%, muscular – 70%) – protein contains more water than Life fat. An adult male – 62% H2O, 17% protein, 15% fat & 6% minerals and glycogen. We can survive much longer without food than without H20.  Typical Daily H20 Intake & Output Food: 700 – 1000ml INTAKE Drink: 550 – 1500ml Metabolic: 200 – 300ml Kidney (urine): 500 – 1400ml Skin*: 450 – 900ml OUTPUT Lungs: 350ml Feces**: 150ml * Hot environment – 10-20 times more per hour ** severe diarrhea lose more  1. Heat capacity (high) Amount of energy required to raise its temperature 1oC H2O’s high heat capacity – it takes a lot of heat to change Function the temperature of the body of H20 2. Cooling ability Warm: blood vessels dilate (vasodilatation) – component of sweat.  3. Participation in metabolism Nearly all chemical reaction of metabolism involved H20 4. Control osmotic pressure in the body and maintain proper balance between electrolyte. Function of 5. Main constituent of blood, major transport H20 mechanism (oxygen, nutrients, hormones), and carry waste product of metabolism. 6. Body fluids Shock absorption, lubrication (synovial fluid), cleansing (tears) & protection (amniotic fluid)  Based on body size & composition, activity level, temperature & humidity. 2.4 liters (10 cups) of water each day. H20 RDA RDA- 1.0ml to 1.5ml per kcal expended. Athletes & very active people need much more than this especially if they train in warm, humid climates. H2O RDA H20 Balance Our bodies maintain H2O balance by mechanisms that control H2O intake (thirst) & H2O excretion Low H2O – kidney conserve H2O (reabsorb H2O, decreasing urine volume, concentrating the urine) High H2O – kidney form & excrete a large volume of dilute urine. Regulation of Fluid Excretion H2O Deficit Increased [Na+] stimulates osmoreceptors Pituitary gland released antidiuratic hormone (ADH) EFFECT ON KIDNEY conserve H2O excrete solute in highly [urine]  Alcohol Substances Caffeine That Affect Fluid Balance Diuretic medication High protein diet Hydration Status & Performance Insensible Water Loss by continuous evaporation of water from the lungs and skin, typically accounts for about one quarter to one half of daily fluid loss Other factors: High altitude Low humidity High temperature Insensible Water Loss Commonly used strategies to help prevent excessive increase in body temperature during exercise in hot environment Skin wetting Hyperhydration Rehydration Recommendations on Fluid Replacement for Endurance Event Before Event Athletes are encourage to drink 13-20 oz (400- 600ml) or about 1½ to 2½ cups of fluid 2-3 hours prior to exercise Larger athletes may consume a greater quantity Fluid consume not just only water but carbs and electrolytes. Sports drinks containing 4-8% carbs are preferred Recommendations on Fluid Replacement for Endurance Event During event Drink a small amount of fluid: 6-12 oz (150-350ml) or about ¾ or 1½ cups of fluid every 15-20 minutes during event. Additional fluid may be necessary in hot environment and heavy sweating. Fluid consumption maybe enhance when fluid is cooler (5-15 ºC) Fluid consumption maybe enhance when fluid is flavored. Sports drink containing 6-8% carbs would be sufficient. Glucose, sucrose and maltodextrins are preferred over fructose. (overloaded of fructose will make the liver convert it to fat which are exported as VLDL cholesterol) Add sodium (0.5-0.7g/L) Recommendations on Fluid Replacement for Endurance Event After event Drink 16½ - 33oz (500-1000ml) or about 2-4 cups of fluid during the first 30min after event. Fluid consumption maybe enhance when fluid is cooler and flavored. Then consume at least 1L every 1-2 hour thereafter until consumption has matched 150% of sweat weight loss to allow complete rehydration. Fluid containing carbs and electrolytes serve better than just water alone.  Factors that can influence the rate of absorption of sports drink. Temperature Cooler solutions (5-15oC) may empty the stomach more quickly than warmer or hot solutions. Cooler drinks are more enjoyable and promote greater consumption. Osmolality and energy content High Fructose Corn Syrup has lower Osmolality than sucrose or glucose. Concentration of more than 8% carbohydrate in the stomach can slow down gastric emptying. Exercise intensity Athletes performing at higher intensities for a relatively short time (e.g., 10km run) might benefit more from consuming sport drinks. Mild to moderate exercise intensity ( 2% body weight loss from water deficit Amount and rate of fluid replacement depends on individual sweating rate, exercise duration, and opportunities to rehydrate Individuals should monitor body weight changes during training/competition sessions to estimate fluid losses during a particular exercise task Possible starting point for marathon runners is to drink ad libitum 0.4-0.8 liter of fluids per hour. Smaller runners at 0.4 liter and bigger runners at 0.8 liter.  Heat acclimitization Favorable adaptations – ↑ total body water and blood volume ↑ sodium and protein – ↑ cardiac output to muscles and skin – ↑ size of sweat glands and ↑ sweat rate – ↑ sweating at a lower core temperature – ↓ muscle glycogen usage – ↓ loss of body salt and sodium – ↓ in rate of core temperature increase – ↓ psychological feeling of stress Figure 9.13