+ A.2 Environmental factors and physical performance

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A.2 Environmental factors and physical performance

+A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body

In Pairs (2), research the following.

Cellular metabolism Exothermic reaction Endothermic reaction


Cellular metabolism – all chemical reactions taking place within the body, including respiration of working cells during physical exercise.Energy needed to sustain vital functions

These cells take in energy through fuel (food) and convert into chemical energy, which is converted into mechanical energy (e.g. Muscle contraction)


ATP – Adenosine Triphosphate – energy-rich compound that powers all of the cell’s energy-requiring processes.

Cell respiration – the controlled release of energy in the form of ATP

In humans, ATP is created through cellular respiration, which uses O2 to convert glucose into CO2 and H2O.

+A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body Energy liberation - The energy liberated (released)

from dietary nutrients through reactions occurring in metabolism results in both heat production and the conservation of energy within the compound ATP.

Cellular metabolism

Food + O2 + ADP ATP + H2O + CO2 + Heat (entrophy)

http://www.colorado.edu/intphys/Class/IPHY3730/image/figure2a.jpg



The energy released when glucose (sugar) reacts with O2 is used to produce ATP. However, only a fraction of the released energy goes into the high-energy bonds of ATP. Since the overall reaction is exergonic, some energy is lost as heat.

Exergonic (catabolism) – to release energy in the form of work. Breaking down energy.

Energy released = an in body temperature.


As cellular metabolism increases so does the production of heat

Factors that affect the metabolic rate:Physical activityFoodEnvironmental temperature

+A.2.2 State the normal physiological range for core body temperature

Normal core body temperature of a healthy, resting adult human is 98.6 (+.4) degrees Fahrenheit or 37.0 (+.6 to 1) degrees Celsius.

Elevated body temperature is usually above 39o C or 102o F. (Hyperthermia)

Hypothermia – low body temperature (around 34 to 35o C or 93.2o F.

http://hypertextbook.com/facts/LenaWong.shtml

+A.2.3 Outline how the body thermoregulates in hot and cold environments. Conduction: Involves skin contact with an object of a

different temperature. The body will lose temperature when in contact with colder surfaces (e.g. ice packs snow, wet clothing, cold water). Conversely, the body will increase in temperature when in contact with warmer surfaces (e.g. a hot road, warm water, electric blanket)

Browne et.al 2000

+A.2.3 Outline how the body thermoregulates in hot and cold environments.

Convection: Body temperature is influenced by the flow of air across the skin – as in the cooling experience from a fan.

Cyclists gain a cooling effect through convection.

In cold climates, strong air currents are a serious threat. This is commonly known as “wind chill.” If the air currents are warmer than body temperature, the body will gain heat.

Browne et.al 2000


Radiation: Transfer of energy waves (e.g. sun, fireplace, radiator)

Sent out from one object, absorbed by another.

The body absorbs radiant heat energy when temperature of the environment is higher than skin temperature.


Evaporation: Is the most important avenue for heat loss from the body. As sweat evaporates from the skin, a cooling effect is achieved, thus releasing heat from the body.

+A2.4 Discuss the significance of humidity and wind in relation to body heat loss

Research task: In pairs (2)

Humidity: Wind:

+A2.5 Describe the formation of sweat and the sweat response

Sweat glands are located over most of the body, and release fluids through the pores onto the surface of the body. This is one of the mechanisms the body uses to regulate temperature through the evaporation of sweat as it spreads over the surface of the skin.

Individuals vary hugely in their capacity to sweat.


Sweating is a response to the rise in core temperature

Sweating causes a decrease in core temperature (this is a release of what?)

Cooled venous blood returns to the body’s core

Sweat Response

http://en.wikipedia.org/wiki/Perspiration


Because of their relatively large body surface area and immature sweat response, infants, children and young adolescents are more susceptible to complications associated with exercise performed in the heat and cold.

Refer to the link below:

http://www.gssiweb.com/Article/sse-51-children%27s-responses-to-exercise-in-cold-climates-health-implications

http://www.gssiweb.com/Article/see-51-children's-responses-to-exercise-in-cold-climates-health-implications




+A.2.6 Discuss the physiological responses that occur during prolonged exercise in the heat. Submaximal exercise performed for more than

15 minutes produces progressive water loss through sweating and a fluid shift from plasma to tissues. (McArdle, Katch & Katch, 2007)

An increase of body temperature results in a lower venous return to the heart, and a small decrease in blood volume from sweating.

A reduction in SV causes the HR to increase to maintain cardiac output.

What is this phenomenon called?

IB SEHS Course Guide

+A.2.6 Discuss the physiological responses that occur during prolonged exercise in the heat.

Energy metabolism

The reduced muscle blood flow in high temperatures results in increased glycogen breakdown in the muscle, and higher levels of muscle and blood lactate in comparison to the same exercise performed in a cooler environment.

IB SEHS Course Guide

+A.2.6 Discuss the physiological responses that occur during prolonged

exercise in the heat.• Elevated heart rate

• Increased vasodilation to assist with cooling

• Reduced muscle blood flow in high temperatures resulting in increased glycogen breakdown in the muscle and higher levels of muscle and blood lactate in comparison to the same exercise performed in a cooler environment.

• Reduced blood volume due to excessive sweating. Thus a reduced cooling ability of circulating blood.

• Reduced sweating response: this increases core temperature.

• Death

+A.2.7 Discuss the health risks associated with exercising in the heat.

Hyperthermia – core body temperature has risen dangerously high Confusion, hot skin, headache, and in severe

cases, can lead to coma and death.

Heat Cramps -

Heat Exhaustion

Heat Stroke

Heat Related Illnesses

http://www.drreddy.com/heat.html

+A.2.8 Outline what steps should be taken to prevent and to subsequently treat heat-related disorders.

Prevention Hydrate Cover – hats, shade Take breaks or stop the activity Acclimatize – later discussion Massage/stretching – heat cramps Lower intensity


TreatmentHeat cramps –

Stop exercisingDrink water

Heat ExhaustionStop exercisingMove to a cool environmentDrink water


Heat Stroke Medical attention Immerse in cold /ice water Move to cool environment Take off clothing Use ice packs Use cold, wet towels

+A.2.9 Describe how an athlete should acclimatize to heat stress.

Performing training sessions in similar environmental conditions (heat and humidity) from 5 to 10 days results in total heat acclimatization.

In pairs – Research and discuss how you would prepare your national soccer team ( to compete in the hot environment (>40oC/104oF) of the 2022 Qatar soccer World Cup.

+A.2.10 Discuss the physiological and metabolic adaptations that occur with heat acclimatization.

Read and summarize the link below.

http://www.answers.com/topic/heat-acclimatization



+A.2.10 Discuss the physiological and metabolic adaptations that occur with heat acclimatization.

plasma volume

sweat response

rate of muscle glycogen utilization

+A.2.11 Outline the principal means by which the body maintains core temperature in cold environments.

Shivering – method used to raise temperature

Non-shivering – fat (brown fat)

Peripheral vasoconstriction – prevents blood from going to the skin in order to retain heat…the vessels need to close here, unlike vasodilation, which is needed when exercising in the heat.

+A.2.12 Explain why the body surface area-to-body mass ratio is important for heat preservation.

Tall, heavy individuals have a small body surface area-to-body-mass ratio, which makes them less susceptible to hypothermia.

Small children tend to have a large body surface area-to-body mass ratio compared to adults. more difficult to maintain normal body

temperature in the cold.

+A.2.13 Outline the importance of wind-chill in relation to body heat.

A chill factor created by the increase in the rate of heat loss via convection and conduction caused by wind.

Look on page 185 of your text.

+A.2.14 Explain why swimming in cold water represents a particular challenge to the body’s ability to thermoregulate.

Cold water immersion = loss of body heat Risk of hypothermia – low core body temperature Increase in body heat loss due to convective

heat loss As with other cold conditions, increasing

intensity of activity (e.g. going faster), the metabolic rate can compensate for the increase in heat loss

+A.2.15 Discuss the physiological responses to exercise in the cold.

Muscle function –

Metabolic responses -

+A.2.16 Describe the health risks of exercising in the cold, including cold water. Frostbite

Hypothermia

+A.2.17 Discuss the precautions that should be taken when exercising in the cold. Appropriate clothing

Used as a barrier/protection Insulation offered is measured in a unit called clo 1 clo = 0.155m2 KW-1

Documents

+ A.2 Environmental factors and physical performance