7: exercise in unusual environments Flashcards
Altitude
air is compressible;
a given volume at sea level (SL) contains more molecules than at ALT -
ALT a given volume contains less molecules that at sea level
what is air made up of?
N2=79.04%; Co2=0.03%; O2=20.93%
constant up to 110,000m
What is same at any altitude?
the concentration of gases do not change, but the content per unit volume decreases
What us the partial pressure of nitrogen?
600mmHG
what is the PP of O2?
159 mmHg
what is the PP of co2?
0.23 mmHg
as one move up in altitude, if barometric pressure drops then..
everything else will drop as well
driving pressure to move o2 along the o2 transport cascade is compromised
Ventilation (VE):
the movement of air between the environment and the lungs via inhalation and exhalation
make alveolar ventiatiolation as close to the outside as possible by breathing slower and deeper. but trouble is blowing off co2
Hyperventilation (HV)
changes the partial pressure of oxygen in the alveoli and
improves oxygenation of the blood
hyperventilation: adaptive
the greater the HV the more closely the alveolar air resembles inspired air –facilitates O2 loading in the lungs
hyperventiolation: “non-adaptive”
: decrease es partial pressure of CO2 at the alveolar level and this causes blood pH to increase (alkalosis)
oxyHb curve shifts to facilitate loading
-Bicarbonate is excreted in the urine
at altitude what type of breathing do you want to do?
deep nad slow breathing
CO2 + water –> carbonic acid
-the formation of carbonic acid from CO2 and water
is favored by the high PCO2 found in tissue capillaries
-in the lung there is a low PCO2 and thus the formation
of CO2 and H2O from H2CO3 occurs
why does heart rate go up with altitude?
becuase less o2 so the heart has to pump harder to obtain o2
as you go higher and higher what happens to your heart rate and o2?
altitude 0> icnreaes HR
altitude –> decrease o2
they will meet at one pt and you need to not do anything and just rest
HEMATOLOGICAL CHANGES:
1) Hb concentration (1 g of Hb can carry 1.34 ml of O2)
2) the extent to which Hb is saturated (SaO2)
Exercise in the Heat
–vasodilation –dehydration, –hyponatremia, –heat cramps, –heat exhaustion, –heat stroke evaporation is always NEGATIVE!
Latent heat of evaoporation
The input energy required to change the state from liquid to vapor at constant temperature
Heat Illness:
syndromes overlap and frequently occur in combinations-regarded as a continuum
1) heat cramps
2) heat exchuastion
3) heat stroke
heat cramps
painful muscle contractions which occur during or after work in the heat
Heat exhaustion
characterized by weakness, fatigue, headache, nausea and diarrhea.
Heat stroke
potentially fatal illness, a state of thermoregulation failure characterized by disturbance of the nervous system (poor limb co-ordination, delirium, convulsions, grand mal seizures) by generalized anhidrosis and by a rectal temp above 40.6°C (variability in threshold up to 41.1°C) often hot, dry skin
What happens to HR and SV when temperature increases?
will raise; your HR will hit max at high temperatures
SV will decrease
Cardiovascular drift
Results from
–Dehydration
–Reduction in SV
•HR drifts upward to maintain same Q
Will you ever reach your peak Q when temp increases?
NO; eventually Q will plateua
Submaximal Exercise
Need a given vo2 for a particular pace
No change in extraction or hematocrit.
If you lose fluid over time, stroke volume willl start to decline.
In order to maintain Q Pyou need to increase heart rate.
Has to accommodate the drop in stroke volume (that decreasing)
Maximum heart rate cannot go any higher = crash
Exercise in the Cold
- vasoconstriction (conserve heat)
- shivering (generating heat involuntarily)
- hypothermia
- frost bite
- heart rate –> increase
- heat loss
- cold water
- hunting response (Cold induced vasodilation dilation)
- body fat
- hydration
Pollution: effective dose:
ED= [ ] (ppm) x volime (L/min) x exposure time (min)
all 3 variables have na impact
Why are athletes at risk?
1) the respiratory minute volume is increased
up to 20 fold
-a proportionate increase in the quantity
of pollutants inhaled
2) a larger fraction of air is inhaled
through the mouth
3) increased airflow velocities carries both
particles and vapors deeper into the
respiratory tract
4) various organs/systems (heart/lung) may be more vulnerable to the effects of pollutants if they must function at maximal capacity.
Types of Pollution:
Primary:
emitted directly from a source and
undergo little or no chemical change in
the atmosphere
e.g.) CO, CO2, SO2, NO and particulate matter
Types of pollution:
Secondary:
formed from the chemical reaction of
emitted and natural precursors in the atmosphere
e.g.) Ozone and peroxyacetyl nitrate (PAN)
Carbon monoxide
odourless; colourless
- highly toxic/ethal
- results form the incomplete combustion of carbon-containing organic materials
- automobiles and cigarette smoke
extremely high affinity for HB
binds 200-250 times mreo readily than o2, formes carboxyhb (COHb)
noramlly 0.05 - 1% COHb
2-5% is associated with negative physiolgoical effects
Sulphur Dioxides
Family of cmpds (S0x) burning fossil fuel (sulphuric acid)
S02-90%
soluble gas
an upper respiratory tract irritant
bronchocontstriction; increased airway resistant
Fine particulants
-dust, smoke, pollen, bacteria, acid aerosols, other compounds
-5-10 um-deposited in nasopharyngeal region
—-inflammation
-3-5 um- tracheobronchial region
—-bronchospasm
-0.5-3 um- reach the alveoli
Cleared by phagocytosis, mucous
Ozone (03)
-a highly reactive secondary pollutant formed
by the interaction of oxygen, nitrogen,
hydrocarbons and UV
-conc increases during the day-greatest
between noon and 4 when sunlight is most favorable
How to Minimize Pollution Related Problems
When Exercising
- Avoid peak traffic hours
- Avoid hours when the sun is brightest;
- -Ozone levels increase on sunny days - Exercise in open areas
- pollutants can be trapped under trees/shade
- air currents disperse pollutants - Be aware of air quality/pollution alerts
Oxidative stress
- a shift of pro-oxidant/antioxidant balance in favor of the former-a consequence of O2 rich environment
- an imbalance between antioxidant defenses and pro-oxidant insults
- -> biological damage
Antioxidant
wide variety of chemically and functionally unrelated substances
-any substance that, when presented at low concentration, compared to oxidants delays or decreases oxidation
Biological Antioxidant
protects against damage in biological systems
regenerated by biological reductants
Free Radical
a species capable of independent existence
that contains one or more unpaired electrons in an orbital (not to be confused with ions)
needed for life-ETC, but may also be harmful
Free Radical Theory of Aging-
Higher metabolic rate, more O2, more FR, more or sooner aging?
Sources of FR
1) Radiation
2) Enviromental chemicals:
Alcoholic beverages,
anti-cancer, parasitic drugs.
3) Metabolism:
Ozone, NO2 (Smog), gas fuels, heavetals
Strenuous Exercise
O2 + 1 electron=superoxide anion (O2-)
not dangerous by itself but can extract an electron from nearby biocompounds–causing a FR chain reaction, therefore must be kept in check.
Haber-Weiss Reaction
-slow and practically non-existent in living organisms
-a catalyzing agent (possibly iron) is necessary to drive the reaction
thus, more likely,
“iron catalyzed Haber-Weiss reaction
generation of highly reactive from
moderately reactive FR
O2 + 2 electrons= hydrogen peroxide (H2O2)
not a true FR
- Reactive Oxygen Species (ROS) or Oxygen Reactive Species (ORS)
- H2O2 formation in the mitochondria is linked directly to the energy coupling mechanism
O2 + 3 electrons=OH x Hydroxyl radical
Hydroxyl radical-most dangerous but practically nonexistent in living organisms-needs catalyst (iron)
