This document discusses how environmental factors like temperature, altitude and humidity can influence human performance. It covers the body's thermoregulation processes for maintaining core temperature during cold and heat exposure. During cold, the body increases heat production and conservation through vascular, muscular and hormonal adjustments. During heat, the main mechanisms of heat loss are radiation, conduction, convection and evaporation. Acclimatization to altitude involves both immediate and long-term adaptations to the reduced oxygen levels to improve tolerance. The key factors for exercising in heat and cold are maintaining hydration and avoiding large fluctuations in core temperature.
1 of 28
Downloaded 55 times
More Related Content
Environmental influence on performance
1. Environmental Influence
on Performance
Sukanya Dandekar (MPT student )
Dr. Suvarna Ganvir (PhD,Prof & H.O.D)
Dept. of Neurophysiotherapy
D.V.V.P.F.s College of Physiotherapy,
Ahmednagar
2. THERMOREGULATION
Normal body temperature fluctuates
several degrees during the day in response
to physical activity, emotions, and ambient
temperature variation.
A person can tolerate a drop in core
temperature of 18F (10C) but only an
increase of 5C (9F).
Understanding thermoregulation and the
most effective ways to support
temperature control mechanisms can
dramatically reduce heat-related tragedies.
3. THERMAL BALANCE
heat loss as the body attempts to
maintain thermal neutrality.
This balance results from
integrative mechanisms that
accompllish the following:
1. Alter heat transfer to the
periphery (shell)
2. Regulate evaporative cooling
3. Vary the rate of heat production
5. HYPOTHALAMIC REGULATION
OF BODY TEMPERATURE
Central coordinating center for
temperature regulation.
Regulate temperature within a narrow
range of 37C
Temperature-regulating mechanisms
become activated in two ways:
1. Thermal receptors in the skin
provide peripheral input
2. Temperature changes in blood that
perfuses the hypothalamus directly
6. COLD EXPOSURE
Heat production and heat
conservation occurs
Three integrated factors regulate
body temperature during cold
exposure:
1. Vascular adjustments
2. Muscular adjustments
3. Hormonal adjustments
7. 1. Vascular adjustments:
2. Muscular activity: Shivering,
physical activity generates energy
3. Hormonal output: Increased
release of the epinephrine and
norepinephrine. Prolonged cold
stress also increases release of
thyroxine to elevate resting
metabolism.
8. HEAT EXPOSURE
Causes heat loss
Integrated factors that regulate
body temperature during heat
exposure:
1. Radiation
2. Conduction
3. Convection
4. Evapouration
9. Radiation Heat is tranferred from more hot
to less hot
Conduction Direct transfer of heat from skin
surface to air molecules
Convection Air movement replacement of hot air
by cool air
Eg fan
Evapourati
on
Water from resp passages & skin
surface
1 vapourized litre 580Kcal
Sweating : glands secrete hypotonic
solution (NaCl 0.2-0.4%)
10. Heat Loss in High Humidity
:Sweat evaporation from the skin
depends on three factors:
1. Surface exposed to the
environment
2. Temperature and relative
humidity of ambient air
3. Convective air currents around
the body
11. EFFECTS OF CLOTHING ON
THERMOREGULATION
Cold :
Air & cloth conduct air poorly
To conserve heat, increase layers
of these
Dry clothing also conserves heat
12. Warm:
Wet clothing helps heat loss
more than dry clothing
Dry clothing retards heat
exchange
Increasing surface area to the air
also helps heat loss
15. Altitude
Air density altitude
PO2 of air altitude
O2 loading: ie. Hb saturation with
oxygen
Till 3048m there is small
change
After that it decreases
16. ACCLIMATIZATION
Adaptive responses in physiology
& metabolism that improve
tolerance to altitude hypoxia
There are immediate and long-
term adaptations
17. system immediate Long-term
pulmonary Hyperventilation Hyperventilation
Acid base Alkaline Excretion of base
therefore alkaline
Cardiovascular submax HR
submax Cardiac
Output
Stroke volume
Max cardiac
output
Submax HR
Submax Cardiac
Output
Stroke volume
Max Cardiac
Output
Haematologic Plasma volume
Haematocrit
Hb conc.
No. of RBCs
Local Capillarization of
skeletal ms
RBC
Mitochondria no
Aerobic enzymes
Body wt. & lean
mass
19. Acid- base:
Air CO2
Wash out of CO2
PaCO2
Physiologic disequilibrium
pH (loss of H2CO)
Alkaline
Kidneys excrete base HCO3
Restoration of normal pH
20. No of RBC:
PO2 Polycythemia
Lactate paradox :
Lactate accumulation reduced
without increase in tissue
oxygenation when hypoxaemia
associated with high altitude should
promote lactate accumulation
glucose mobilisation from liver
lactate formation
21. Acclimatization time :
2300m 2weeks
After that every 610m 1
week
Adaptations dissipate within 2-3
weeks after returning to sea
level.
22. EXERCISE IN THE HEAT
Responses to exercise in heat;
1. Body maintains BP
2. Core temperature & regulated
at high level
3. Water loss: dehydration
23. Adequate hydration is the key to
maintain all the systems
2 strategies :
Prehydration :
1. 500ml before sleeping
2. 500 ml upon awakening
3. 400-600ml 2o min before exercise
Hydration during exercise:
Prehydration does not replace water loss
during exercise
1. 遜 l 2-3 hrs before exercise
2. 200ml- after warm up
3. 800 ml per hour of exercise
24. EXERCISE IN THE COLD
Responses to exercise in heat;
1. Body maintains BP
2. Core temperature
3. Water loss : airway moisture loss
Less physiologic adaptation to
cold than heat exposure
25. EXERCISE AT HIGH ALTITUDES
Sea level performance does not
affect performance at high level,
vice versa
7 days- intermittent high altitude
exposure increases performance
& induces physiologic exercise
26. For optimizing performance
live high , tarin low
Athletes lived at 2500m but
trained at 1000-1250m regularly
They showed greater increase in
Vo2 max and performance than
those who stayed only at 2500m