Option - A2
Environmental Factors and
Physical Performance
I. Cellular Metabolism and Heat Production
*using and re-synthesizing ATP produces heat.
*60-70% of energy produced is lost as heat.
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In other words, the energy released during
cellular respiration is used to produce ATP.
However, only a fraction of the released
energy goes into making ATP.
Overall the reaction is exergonic. (releases
energy)
II. Thermoregulation : the human body works
to maintain an average core temperature.
37°C + .6° (98.6°F)
Normal core body
Resting adult 98.6 °F (37°C)
Core temperature variation
Metabolism
Faster metabolism = higher temp.
Time of day
More active times = increase temp.
Part of body used to measure temperature
rectal – most accurate, slightly higher
(99.6 °F or 37.6 °C)
oral – easiest, used for normal range
axillary - inaccurate (97.6 °F or 36.4 °C)
ear – tympanic membrane temp. run higher than normal
Balancing heat in the human body
Heat loss from the body
1. Radiation:
the transfer of
energy waves between two
objects of different temps.
Example:
Atmosphere temperatures
2. Convection: the transfer of heat from one
place to another by the motion air or water.
*cool wind blowing over the skin.
*warm blood circulating through the body
*water in a pool/ocean
Temperature change is always
from hot to cold.
3. Conduction: the transfer of heat energy
between two objects in direct contact.
Examples
ice packs, snow, wet
clothing, cold water.
hot road, warm water,
electric blanket.
4. Evaporation: the majority of heat lost
during exercise is through the evaporation
of sweat. This process takes energy which
results in cooling.
As sweat evaporates
from the skin, a cooling
effect is achieved thus
releasing heat from the
body.
Which mechanisms for heat loss are used
more often by our bodies at rest?
During exercise?
• How do we thermoregulate our bodies? 8 minutes
III. Hot/Humid Environments: reduce the temp.
gradient between the skin and the outside environ.
Humidity reduces the amount of evaporation from
the skin.
A. When the outside temp.
approaches body temp.
the body responds by:
*sweating
*increasing respiration
*altering the rate and depth
of blood circulation
1. The Sweat Response
*thermal receptors in the skin
sense temp. change
*the hypothalamus is the
regulatory center.
*signals from the
hypothalamus cause
vasodilation and trigger
sweat glands to decrease
core temp.
2. Heat Effects on the Circulatory System
*excessive water loss
increases blood viscosity.
*blood flow to the muscles
decreases, increasing
glycogen use.
*blood flow increases to the
external surface of the
skin.
*decreased stroke vol. and
increased heart rate
B. Health Risks Assoc. with Exercising in the Heat
1. Heat Cramps: cramping,
mostly in the legs,
caused by salt
imbalances.
2. Heat Syncope: feeling
faint, dizzy from heat.
3. Heat Exhaustion:
excessive water and salt
loss causing headaches
and dizziness.
4. Heat Stroke: body temp.
rises to 105 causing
lethargy, confusion and
unconsciousness
C. Prevention of Heat Related Disorders
1. Acclimatization:
training in similar
environmental
conditions 5-10 days
while initially reducing
training intensity.
*increases blood vol.,
sweat response and
reduces the rate of
muscle glycogen use.
Prevention and Treatment of Heat Related
Disorders
2. Proper hydration
before
training/event.
3. Educate yourself of
the symptoms.
D. Treatment of Heat Related Disorders
1. Move to cool
environment.
2. Rehydrate
3. Place ice packs on
the neck, groin and
underarms
4. Loosen/remove
clothing
IV. Thermoregulation in Cold Environments
A. Physiological Responses
1. Shivering: when muscles
around the vital organs
shake in an attempt to
create warmth by
expending energy.
2. Non-shivering thermogenesis: a rise in
metabolism that is not related to muscular
activities.
*greater oxygen consumption metabolizes fats to
generate heat.
*common in infants due to more brown fat in the
body. (packed with mitochondria)
3. Peripheral Vasocontriction: blood vessels in
the skin constrict to divert blood to the core.
B. Body surface area-to-body mass ratio: smaller
people and children have a larger ratio and lose
heat and fluids at a faster rate.
C. Wind chill: the felt air temp. on exposed skin
due to the convective cooling process of the wind.
D. Heat loss in Swimming: swimming increases
convective heat loss resulting in:
*the cooling of nerve
and muscle fibers
*swimming and
breath coordination
become difficult
E. Health Risks of Exercising in the Cold
1. Hypothermia: when
the core temp. drops
below the required
temp., 350, for basic
metabolism.
*fatigue
*confusion and irrational
thinking
*poor coordination and
balance
2. Frostbite: Ice crystal formation in the tissues of
exposed skin to extreme cold temps.
F. Precautionary Measures for Exercising in the Cold
*dress in layers to insulate
the body. .6 cm of
clothing adds 1 (clo) of
insulation.
*Keep clothing from
getting wet
*cover the head, neck and
hands
Non-Nutritional Ergogenic Aids in Sport
A. The following
ergogenic aids are
banned by the
International Olympic
Committee (IOC) and
the World Anti-Doping
Agency (WADA)
*anabolic steroids
*hormones (EPO)
*diuretics and
masking agents
*beta blockers
*stimulants
1. Anabolic Steroids: substances that mimic the
effects of testosterone. The increase protein
synthesis resulting in the build-up of muscle.
Negative Effects
*high cholesterol
*acne
*high blood pressure
*liver damage
*testicular atrophy
*gynecomastia
*aggressive behavior
http://www.youtube.com/watch?v=qfxoqje1
X7o&feature=youtu.be
2. Erythropoietin: (EPO) is a hormone produced
naturally in the kidney that stimulates RBC
development in bone marrow.
*instead of blood doping
endurance athletes
are shooting EPO.
Negative Effects
*increased blood
viscosity
*blood clots
(stroke/heart attack)
*sudden death during
sleep
http://www.youtube.com/watch?v=t6OP
h_a11QA 5 min
3. Diuretics and Masking Agents: are used to increase
water loss and conceal the banned substance in the
urine.
Negative Effects
*dehydration
*cramping
*loss of electrolytes
*drop in blood pressure
http://www.youtube.com/watch?v=H4Ua9q_0Os8
3 ½ minutes
4. Beta-Blockers: medications used to block the effects
of adrenaline. They reduce heart rate, blood pressure,
muscle tremors and anxiety.
Negative Effects
*severe blood sugar
changes
*heart failure
*weight gain
*extreme fatigue
Kim Jong Su
http://www.youtube.com/watch?v=WUuY3paZWs
3 min
5. Stimulants: any substance that increases
alertness and physical performance. Ex. Caffeine,
cocaine and amphetamines.
Negative Effects
*irregular heart beat
*sleeplessness
*dizziness
*anxiety
Note: a caffeine level of
12 mg/L of urine is
acceptable by the
IOC.
http://www.youtube.com/watch?v=VvKQ2kVBwTU&list=PLxlVzd1n0m3tncpcYf
u29_MCCJGCkC5vL 53 min