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Nutrition for Fitness Professionals. Chapter 8 Replacing Sweat Loss. Exercise and Sweat. Muscles generate 20 times more heat during exercise Sweat evaporates and cools the skin This cools the blood Which cools the core temperature. Body Temperature. Normal: 98.6 F (37 Celsius)
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Nutrition for Fitness Professionals Chapter 8 Replacing Sweat Loss
Exercise and Sweat • Muscles generate 20 times more heat during exercise • Sweat evaporates and cools the skin • This cools the blood • Which cools the core temperature
Body Temperature • Normal: 98.6 F (37 Celsius) • Cell damage: 106 F (41 Celsius) • Cell protein coagulates: 107.6 F (42 Celsius) • Do not overheat! • Stay hydrated • Know your sweat rate and plan ahead
Staying Hydrated • Weigh before and after exercise • 1 lb loss = 13-16 oz (replace 80-100%) • 1 oz = 1 gulp • 16 oz = 1 pint • Drink chilled and palatable fluids • Set an alarm to drink every 15 minutes • We get 20-30% of our fluids from food!
Thirst • When body fluid is highly concentrated • Sodium concentration • Thirst may be unreliable for athletes losing significant amounts of sweat • Thirst can be blunted by exercise! • We voluntarily replace only 2/3 of sweat loss • Stop drinking if stomach is sloshing
Dehydration • 1% body weight can be lost before you feel thirsty • 1.5 lbs/3 cups/ 24 oz • Heart must beat 3-4 more times per minute • 2% loss = dehydration • 3% loss = significantly impaired performance • 9-12% loss = possible death
How Much Water is Lost? • Depends on • Sport • Body size • Exercise intensity • Clothing • Weather • Acclimatization • Fitness Level
Other Clues? • Check color of urine • Dark and scanty = dehydration • Pale yellow = adequate hydration • B vitamins can make urine appear bright yellow • Chronic fatigue • Lethargy • Headaches • Dehydration is cumulative
Pre-Exercise Hydration • 2-3 ml per lb at least 4 hours prior • 300-400 ml = 10-15 oz • Sodium will stimulate thirst and help fluid retention • Don’t over hydrate • Can lead to hyponatremia (low sodium) • Too many bathroom trips • Caffeine – less than 200 mg won’t affect hydration status
Hydrating During Exercise • 110-170 mg sodium per 8 oz • 20-50 mg potassium per 8 oz • 12-24 g CHO (5-10% sugar solution) • 50-95 kals • Pretzels and bananas are similar! • Exercising longer than 1 hour • 120-240 kcals CHO will enhance performance
Post Exercise Hydration • Sipping is better than gulping • May take 24-48 hours to fully replenish water • Drinking 50% more than lost will enhance recovery • See P. 154 for a good sports beverage • What do you go for? • Do you need a sports drink?
Other Beverages • OJ – great with breakfast – watch kcals • Soda – ok, but watch sugar and caffeine • Phosphoric acid/caffeine affects calcium in body • Water – get a filter at home • Bottled water does not help environment • Energy drinks – avoid! (Sugar and caffeine) • Green tea – ok, but watch label abusers • Alcohol – avoid! Not good for the body.
Limit Alcohol • Alcohol impairs exercise! • Metabolized as fat calories • Men: 2 drinks or less per day • Women: 1 or less per day • Can you save up?
SPORTS DRINKS • Not necessary unless past 60 minutes • 6-8 % solutions • Avoid alcohol