Phys. Ex. Environment and Performance
4 Types of environments in which performance can take place
exercise in heat
exercise in cold
low pressure environment (altitude)
high pressure environment (under sea)
Which environment do we know most/least about?
heat - most
under sea - least
In the heat environment, the ability to exercise is dependent on (physiological and behavioral)
P - increase heat dissipation
B - decrease artificial insulation
In the cold environment, the ability to exercise is dependent on (physiological and behavioral)
P - increase heat production and storage
B - increase artificial insulation
________ is the air layer that exists between your skin and the first layer of clothing
What is the goal of regulating the microenvironment?
What is thermal balance?
heat production = heat dissipation
_______ thermal balance is when dissipation occurs more than production
________ thermal balance is when production of heat is more than dissipation
Normal body temperature range
36.5-37.5 degrees C
What classification of animals are we?
_____________ are animals that regulate its core temperature independent of the environmental temperature
___________- is an animal whose body temperature becomes the temperature of the environment
Why is our ability to regulate temperature not perfect? (3)
Phases of menstrual cycle
How to measure temperature
What is circadian rhythm?
cycle that repeats itself over 10-24 hours.
Temperature changes based on the time of day
When is your body temperature lowest?
When you first get out of bed, because all night metabolic rate is low as it can be, generating less heat
When is your body temperature highest?
After the evening meal, because during the day the temperature goes up and increases metabolic rate
2 phases of the menstrual cycle
Which phase of the menstrual cycle is the first 14?
Which phase of menstrual cycle makes body temperature higher?
Ludial phase temperature is ___-___ degrees C higher than falicular.
When do you run the risk of heat related issues more often? Why?
ludial because temperature is closer to critical temperature due to hormonal control
What is the worst way to measure body temperature?
sticking thermometer in the mouth
Why do we want to regulate temperature so accurately? (3)
Action of nervous system - fast neural communication
Cellular metabolism - enzymes temperature dependent
Myocardial function - change efficiency
What is core temperature?
the central region of the body temperature
What is peripheral temperature?
5 ways to measure core temperature
How to measure temperature orally
Put thermometer under tongue
Why is it bad to find temperature orally?
temperature changes with every breath they take
What is the most common way to represent temperature in newborn babies?
What is the most accurate representation of core temperature before telemetry?
How is core temperature measured tympanically?
- radioactive chip in ear, push it in next to tympanic membrane, then hold radioactive receiver reading temperature of the brain area (not necessarily core temperature)
How is core temperature measured esophageal?
put someone on their back, put thermoster up their nose, follow nasal passages, comes back and feel it hanging in the back of their throat, they swallow hard until it goes down to a level of the atria. Wire hanging from nose goes into a telethermometer and gives you a core temperature.
How does the telemetry system work?
pill has a magnetic bar attached to it, when magnetic bar is taken off it’s activated, taken with 250mL water 2-4 hours before subject/exercise, travels through digestive system, and someone carries a small box, put it next to their back, and have core temperature in seconds.
What is the problem with telemetry systems?
each pill costs $60 and box is $2500
What is core-shell-environment gradient?
move heat form core to shell to environment direction
What does shell stand for?
What is Tsk?
mean temperature of the skin (peripheral temperature)
Surface thermostesr are placed on 4 locations and numbered:
What is T1?
Other symbols for T1 (3)
Tsk = ?
0.3(T2 + T3) + 0.2(T4 + T5)
Tb means what?
mean temperature of the body
Tb = ?
0.67(T1) + 0.33 (Tsk)
Exercise in heat creates a situation of POSITIVE/NEGATIVE heat balance
Physiological factors that may be impacted upon by exericse in the heat (4)
Maximal oxygen consumption
During brief exercise, max VO2 doesn't fall with short duration exercise unless body temperature rises above ____ degrees C
Why would Vo2 drop in heat environment?
shift of blood from working tissues to the skin
why would Q reduce in heat environent?
reduction in stroke volume
After an hhour or more of exercise in heat, a more consistent drop in max VO2 may occur, __-__%
Why does cardiac output often rise in short duration exercise and long duration mild exericse?
increase in HR, because SV is diminished in heat
directed towards skin for dissipation
Individuals who exercise in the heat for prolonged times can lose more than ___ liters of body fluids per hour, and experience a total weight loss of ___-___% of the total body weight in the course of an endurance event
What happens when blood volume is reduced in heat environment?
Reduce Q, reduce BP
Reduce sweat capacity --> increase temperature
_________ the sum total of the physiological adjustments that occur as a result of repeated exposures to hot environments
______ occurs in natural setting
_____ occurs in artificial setting
5 primary physiological adjustments of acclimatization to heat
1. increased peripheral conductance
2. increased plasma volume
3. increases sweating capacity
4. a fall in the threshold of skin temperature for the onset of sweating
5. better distribution of sweat over the skin
Physiological specifics in adjustments of acclimatization (3)
1. blood flow to the skin decreases - this restores the central blood
2. restoring central blood volume is important for maintaining stroke volume and muscle blood flow during the exercise.
3. this is accompanied by a large increase in sweating and evaporative cooling capacity resulting in greater peripheral conductance of heat.
There is a ____% increase in PV during acclimatization
There is almost a threefold increase in sweating capacity during acclimatization - __-__L per hour
Heat production in cold environments can increase ___ fold
When exercising in the cold, two important concepts must be understood
1. Skin temperature is dependent in a large measure upon the
temperature of the air or water surrounding the skin and is relatively
independent of the exercise load.
2. Any change in core temperature is independent of the ambient temperature and is primarily dependent upon the relative exercise load.
What maximal Vo2 and oxygen cost of submaximal exercise effected by cold?
No, provided it's enough to maintain core temperature
Oxygen cost of submaximal exercise by subjects in wet clothing exercising in wind is __-__% higher than same exercise in comfortable environment
Why is there an increased oxygen cost in wet cold weather?
2 effects of shivering
1. An increase of muscle tome with a periodic simultaneous
contraction of the agonists and antagonists.
2. Causes an increase in metabolic rate, thus an increase in heat production.
5 Circulatory adjustments during cold exposure
1. cutaneous vasoconstriction
2. increase in peripheral vascular resistance
3. increase in systemic blood pressure
4. increase in afterload
5. Lewis-Hunting Response - vasoconstriction followed by bouts of vasodilation.
What is the lewis-hunting response?
vasoconstriction followed by bouts of vasodilation
thermoregulatory oxygen consumption
What is the difference in the VO2 between the cold environment and the neutral environment for the same activity called?
Thermoregulatory oxygen consumption
2 Causes of TVO2
1. chemical heat production - non-shivering thermoregulation - NST
What do you use to dissipate heat?
4 avenues of dissipation (or heat sinks) to maintain core temperature
________ is the transfer of heat using inferred rays
At rest, we dissipate heat via radiation ___% of the time
___________ is the transfer of heat from a warmed object to a cooler object but must have physical contract
Dissipation of heat via conduction is used ___% of the time
______ is the transfer of heat to either air or eater provided that the air or water is moving
Dissipation of heat via convection is used ____% of the time
whatever is left (12%)
_________ can only work if the moisture on your skin evaporates into the air
In order for water to evaporate, you are required to convert water into a gaseous form using energy, called _________________
latent heat of vaporization
What 3 types of dissipation can also be heat sources?
What type of dissipation can NOT be used as a heat source?
If air is already saturated with moisture, it can still accept moisture from your skin. T/F
Dissipation of heat via evaporation occurs ___% of the time
What is our only viable heat source?
3 ways to generate heat
chemical heat production
_______ is a series of microvibrations, contractions and relaxation of antagonist and agonist muscles
What are the chemical activities of body organs?
Chemical heat production
Where is the temperature control center regulated?
hypothalamus in the midbrain
Where is the hypothalamus located?
2 parts of the hypothalamus
Which part of the hypothalamus responds to a heat environment?
What part of the hypothalamus decides when you should start to sweat basd on temperature of blood?
What part of the hypothalamus responds to a cold environment?
What part of the hypothalamus regulates heat conservation events?
What heat conservation events does the posterior hypothalamus take place in? (2)
production of heat
Increase metabolic rate
2 ways to conserve heat
For heat, we VASOCONSTRICT/VASODILATE and cause what?
How does vasodilation cause heat dissipation?
brings blood to the surface and the amount of insulation naturally is going to go down
For cold, we VASOCONTRICT/VASODILATE and cause what?
heat production and conservation
How does vasoconstriction cause heat production and conservation?
Constricts everything and keeps blood in the periphery and makes it harder to dissipate.
When considering the mechanisms of heat transfer - they can only occur due to two physiological occurrences:
- body can change surface temperature by altering skin blood flow
- body can control sweat secretion via the sweat glands
Human skin, regardless of color, absorbs about ___% of the radiant energy that strikes it
The temperature of an object is a measure of what?
Kinetic activity of its molecules
_________ occurs when body temperature rises above 40 degrees C due to lack of evaporative cooling
5 Characteristics of heat exhaustion
Rapid weak pulse
4 Types of thermal distress or illness
_____ is loss of body fluids
_______ is involuntary cramping of skeletal muscle
_______ is characterized by hypotension - weakness caused by inability of the circulation to compensate for teh vasofilation of the peripheral vessels
______ is the complete failure of the hypothalamus