Physiology of performance in extreme environments (B_PPEE)
Summary
Summary Physiology of Performance in Extreme Environments (B_PPEE)
90 views 8 purchases
Course
Physiology of performance in extreme environments (B_PPEE)
Institution
Vrije Universiteit Amsterdam (VU)
Summary of the lectures/seminars of the master subject Physiology of performance in extreme environments. Consists of all the lectures: introduction, climate change, cold, thermal modeling, scientific review, comparative thermal physiology, clinical thermal physiology, altitude, heat, nobel prize t...
Physiology of performance in extreme environments (B_PPEE)
All documents for this subject (3)
Seller
Follow
sofievm
Reviews received
Content preview
Physiology of performance in extreme environments
Lecture 1 – Introduction
Humans > Homeotherm
Mechanisms to cope with thermal extremes
Thermal neutral zone = vasodilation & vasoconstriction
Heat
- Vasodilation
- Sweat loss (max. 3 L/hr = 2458 W)
o Sweat dripping of is not efficient
o Evaporation of sweat has a cooling effect
o Cotton sucks up a lot of sweat → sweat cannot evaporate
▪ Loose fitting shirt is even worse
o Sweat systems
▪ Hormonal control → emotional sweat
▪ Nerve control (sympathetic system) → thermal sweat
o Unacclimatised: more salt in the sweat
- Powerful acclimatization
Cold
- Vasoconstriction
- Shivering: max. 400 W/hr
o Well trained: more shivering
- Fur coat
- Brown fat
➔ Poor acclimatization
Rest: Brains and liver produce most heat (90-100 W/hr)
- Main dry heat loss because of thermal gradient/convection between skin (30°) and air (20°)
Evolution
- Left Africa 40,000 years ago
- Clothing allows extending the habitat behind physiological limits
- Innuits have shorter fingers
- Longer fingers by people who live in a warm climate
Heat balance: M ± R ± C – E = S
M: Metabolism
➢ Total production of all energy
➢ Oxygen measurement in expirated air
➢ Watt = Joule/sec
R: Radiation
➢ Measurement: Temp. difference between skin and environment
C: Convection/Conduction
, ➢ Convection = stroming (wind/water)
➢ Conduction = heat transfer from material to material
➢ Measurement: Temp. difference between skin and environment
E: Evaporation
➢ Wet heat loss
➢ Measurement: weight people before & after exercise
o Correct for clothing and drinking
S: Storage
➢ Difference between heat production & heat loss
➢ Measurement: measuring body core and body skin temperature
o Cold: core 60%, skin 40%
o Warm: core 80%, skin 20%
Heat balance in;
Rest:
- Equilibrium between heat production and heat loss
- Diet induced thermogenesis
Exercise:
- Heat Production exceeds heat loss
- Core temperature increase
- Performance decrement
➢ Example 8 km run thermal balance
o Lower ambient temperature →
lower sweat loss
,Wet and dry heat loss
Thermal balance calculation
Heat balance climb 1500 m
Mass: 82 + 14 kg
Energy: m*g*h =96*9,81*1500 = 1440 kJ needed to climb the mont ventoux
Time: 2 hr (7200 s)
1440000/7200 = 200 Watt of power needed in bike
Power: 200 W
Efficiency: 20%
Total: 80% over = 800 Watt and 20% in bike = 200 Watt
Heat loss: 800 W
Ambient temperature: 35°C
Heat loss has to be cooled: 800/650 = 1,23 Liter/hr evaporation
Ereq: 2.4 l (1 L in 1 hour ~ 650 W)
➢ If you cannot evaporate, than the body core temperature will go up
Heat balance factors
• Climate:
- Wind
- Temperature
- Humidity
• Clothing:
- Isolation value
- Water vapor probability: Barrier against sweat evaporation
• Metabolism
• Individual factors
- Body shape and fat storage
- Heat acclimation status
, Required clothing for thermal neutrality
- Used in the mountains and military
Mortality and heat balance
Weather related mortality
23 year database of daily mortality
Cold-related mortality exceeds heat-related mortality!
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller sofievm. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.50. You're not tied to anything after your purchase.