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Chapter 17. Environment and Exercise. Key Concepts. altitude acclimatization conduction convection core temperature evaporation frostbite heat exhaustion . heat strain heat stress heat stroke hypothermia radiation temperature regulatory center wind chill factor . Review Questions.

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Chapter 17 l.jpg

Chapter 17

Environment and Exercise



Slide3 l.jpg

altitude acclimatization

conduction

convection

core temperature

evaporation

frostbite

heat exhaustion

  • heat strain

  • heat stress

  • heat stroke

  • hypothermia

  • radiation

  • temperature regulatory center

  • wind chill factor



What are the four ways the body loses heat to the environment l.jpg
What are the four ways the body loses heat to the environment?

  • Conduction

  • Convection

  • Radiation

  • Evaporation


Explain heat exchange by conduction l.jpg
Explain heat exchange by conduction.

It is accomplished through physical contact

between one substance and another (e.g., the

body loses heat through conduction when

submerged in cold water).


Explain heat exchange by convection l.jpg
Explain heat exchange by convection.

Heat is transferred by a moving fluid-

liquid or gas (e.g., man submerged in

cold water)


Explain heat exchange by radiation l.jpg
Explain heat exchange by radiation.

Heat is transferred by means of electromagnetic

waves (e.g., sun heating the earth)


Explain heat exchange by evaporation l.jpg
Explain heat exchange by evaporation.

When a liquid changes to a gas, it

requires large amounts of heat energy

(e.g., a refrigerator or a human leaving

the swimming pool)


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How does the body maintain temperature equilibrium within narrow limits under resting conditions?

The regulatory function is brought about by

nervous feedback operating through the

temperature regulatory center in the

hypothalamus.


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In what two ways does the temperature regulatory center of the hypothalamus respond when body temperature is too high?

  • It stimulates the sweat glands to secrete, encouraging evaporative heat loss.

  • It inhibits sympathetic centers in the posterior hypothalamus, reducing the vasoconstrictor tone of the arterioles and microcirculation in the skin.


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In what three ways does the hypothalamus respond when body temperature is too low?

  • It stimulates shivering.

  • It stimulates catecholamine release, increasing the rate of cellular oxidation.

  • It stimulates the thyroid gland, which increases metabolic rates.


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What is the main problem with exercising in cold weather? temperature is too low?

Preventing sudden changes in temperature (chilling)


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For winter sports such as hiking, snowmobiling, and ice fishing, what is the most effective method of conserving heat?

Protecting the torso, for example with a down-

filled vest, helps maintain core body temperature.


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What is the best clothing to wear fishing, what is the most effective method of conserving heat?for very intense winter sports?

  • Should keep athlete warm while waiting to perform and warming up

  • Part of clothing should be able to be removed after warm-up

  • Should be light-weight to allow sweat to evaporate efficiently


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What are the effects fishing, what is the most effective method of conserving heat?of cold acclimatization?

  • Increased basal metabolic rate

  • Decreased peripheral circulation

  • Increased body fatness


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How does wind chill affect an individual exercising in cold weather?

It requires a dramatic increase over resting

metabolism in order for the body to maintain

thermal balance.


Why is it more difficult to exercise in a hot environment than in a cold one l.jpg
Why is it more difficult to exercise in weather?a hot environment than in a cold one?

When environmental temperature approaches

skin temperature, heat loss through convection

and radiation gradually ends, so that the only

means for heat loss is evaporation of sweat.

Radiation and convection reverse their direction

and add heat to the body.


What are the two main problems that could result from exercising in a hot dry environment l.jpg
What are the two main problems that could result from exercising in a hot, dry environment?

  • Severe loads on the cardiovascular system due to increases in heart rate to meet the demands of both exercising muscles and skin circulation.

  • Dehydration because voluntary thirst does not ensure adequate water replacement during exercise.


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How do the problems of exercising in a hot, humid environment compare to exercising in a hot, dry environment?

The problems of increased cardiovascular loads

and dehydration are aggravated in a hot, humid

environment because of the body’s decreased

ability to unload water vapor into an already

loaded ambient atmosphere.


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List some of the guidelines for maintaining proper hydration in athletes during practice or competition during hot weather.

  • Weigh in without clothes before and after exercise

  • For each pound of body weight lost during exercise, drink two cups of fluid

  • Drink a rehydration beverage containing sodium

  • Drink 2.5 cups of fluid two hours before practice or competition

  • Drink 1.5 cups of fluid 15 minutes before the event

  • Drink at least one cup of fluid every 15 to 20 minutes

  • Do not restrict fluids before or during exercise

  • Avoid beverages containing caffeine or alcohol


Name some ways to prevent heat related illnesses l.jpg
Name some ways to in athletes during practice or competition during hot weather.prevent heat-related illnesses.

  • Education

  • Clothing

  • Hydration

  • Fitness


What are some effects of acclimatization to a hot climate l.jpg
What are some effects of acclimatization to a hot climate? in athletes during practice or competition during hot weather.

  • Cooler skin and core temperatures

  • Greater portion of cardiac output available to muscle blood flow

  • Reduction of the level of skin blood flow for temperature regulation


What are some of the causes for the decrease in aerobic power when exercising at high altitudes l.jpg
What are some of the causes for the decrease in aerobic power when exercising at high altitudes?

  • Reduction in oxygen saturation of arterial blood

  • Higher cost of increased lung ventilation


What are the effects of acclimating to high altitudes l.jpg
What are the effects of power when exercising at high altitudes?acclimating to high altitudes?

Increase in:

  • red blood cell count

  • hemoglobin content in the blood

  • plasma volume

  • lung ventilation

  • aerobic enzyme activity

  • capillary density

  • mitochondrial density in skeletal muscle


Useful websites l.jpg
Useful Websites power when exercising at high altitudes?


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Environmental Physiology Lab power when exercising at high altitudes?

www.jsc.nasa.gov/sa/sd/facility/labs/EPL/epl.htm

Temperature and Performance

www-rohan.sdsu.edu/dept/coachsci/csa/

vol36/table.htm

Nutrition and the Athlete: Fluid Replacements

www.ianr.unl.edu/pubs/foods/nf72.htm

The High Altitude Medicine Group

www.high-altitude-medicine.com

OA Guide to High Altitude: Acclimatization and Illness

www.princeton.edu/~oa/safety/altitude.html


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