Nutrition for Fitness Professionals

Nutrition for Fitness Professionals

Chapter 8Replacing Sweat Loss

Chapter 8Replacing Sweat Loss

Exercise and SweatExercise 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 TemperatureBody 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 HydratedStaying 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!

ThirstThirst

• 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

DehydrationDehydration

• 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?How Much Water is Lost?

• Depends on – Sport– Body size– Exercise intensity– Clothing– Weather– Acclimatization– Fitness Level

Other Clues?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 HydrationPre-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 ExerciseHydrating 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 HydrationPost 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 BeveragesOther 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?

• Not necessary unless past 60 minutes

• 6-8 % solutions• Avoid alcohol

SPORTS DRINKSSPORTS DRINKS