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2013-11-04 23:12:33
environmental challenges exercise performance

environmental challenges and exercise performance
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  1. the inability to dissipate excess heat is called:
    heat stress
  2. the ability of the body to maintain constant internal temperature is called:

    elevated heat & humidity increase this challenge by blocking heat dissipation from the body
  3. where are the receptors that detect  increases or decreases in temperature:
    • periphery
    • in and under the skin
    • peritoneal (abdominal) cavity

    • CNS
    • hypothalamus
    • brain stem
    • spinal cord
  4. describe the acute regulation and control of core temperature by the hypothalamus:
    • increased environmental temperature
    • signals from thermosensitive receptors and tempertaure of the blood is detected by the hypothalamus
    • physiolgoical responses: increased heart rate & cardic output, increased vasodilation, accelerated sweating
  5. describe the acute regulation and control of core temperature by the cerebral cortex:
    • increased environmental temperature
    • signals from the skin thermal receptors
    • cerebral cortex
    • voluntary responses: seek cooler environment, drink cold fluids, loosen clothing, take off clothing
  6. what are the 3 factors that determine the thermoregulatory stress that the enviroment imparts on the body:
    • ambient temperature
    • relative humidity: the % of water vapor held in the air
    • wind speed: contributes to the effect of convective cooling
  7. what are the body's 4 basic mechansims that can help maintain core temperature and foster heat loss:
    • convection
    • conduction
    • radiation
    • evaporation
  8. air blowing over the surface of the skin, removes the air warmed by the body and replaces it with cooler air is called:

    the motion of a gas or liquid across a heated surface
  9. physical contact between two surfaces and the direction of heat flow is from the warmer to the cooler object is called:
    • conduction
    • example: cold water over the skin, will promote conduction of heat from the skin to the water
    • placing a person in a cold water bath will reduce body temperature more quickly, effectivly than cool air
  10. molecules in motion that are constantly moving and giving off heat in the form of electromagnetic waves are called:
    • radiation
    • when surrounding heat is greater than body temperature, heat can be gained by the body
    • radiant heat energy: sunlight, reflected sunlight, radiator or sauna
  11. water that is located on the surface of the body's skin and respiratory airways transforms to its gaseous state which absorbs heat and cools the body is called:
  12. list factors that can lead to heat gain:
    • exercise intensity and duration
    • amount of muscular activiation
    • basal metabolic rate (metabolic heat)
  13. describe the process of evaporation:
    • as body temperature rises, sweat production increases
    • sweat reaches the skin and evaporates
    • evaporation accounts for only 8% of heat lost during exercise, but only about 20% at rest
    • insensible water loss removes about 10% of heat
    • dehydration is a potential problem with sweating
  14. what are the circulatory and metabolic responses to heat stress:
    • increased heart rate and cardiac output
    • redirects circulatory blood:  redistributes blood flow to the periphery so heat can be dissipated and blood cooled.
    • reddens skin & flush complexion
    • body temperature increases
    • oxygen uptake increases
    • glycogen depletion is hastened
    • muscle lactate levels increase


    • increased lactate
    • not as much blood flow to the muscles b/c its going to the periphery
    • lactate builds up
    • need blood to carry O2 to the muscle to clear lactate
  15. as sweating increases, what are the effects of high volumes of sweat:
    • blood volume decreases
    • loss of electrolytes
    • release of aldosterone and ADH
  16. what are the influences of body composition on heat stress:

    what are the influences of fitness level on heat stress:
    • body composition
    • larger body mass = greater heat production
    • body fat insulates, make heat loss more difficult

    • fitness level
    • greater fitness = greater cardiac output
    • greater cardiac output = improved ability to dissipate heat
  17. a muscle cramp that occurs when a person is exposed to heat is called:

    what is this cramp a result of:
    a muscle cramp that occurs when a person is exposed to heat is called: heat cramps

    • result of
    • dehydration
    • electrolyte imbalance
    • whole body sodium deficit
    • neuromuscular fatigue

    • triggered by intense exercise
    • characterized by painful, involuntary muscle contractions
  18. when an athlete or any individual sits or stands for a long time in the heat, fainting can occur, called:

    what is this caused by:
    when an athlete or any individual sits or stands for a long time in the heat, fainting can occur, called: heat syncope

    • caused by
    • excessive peripheral dilation
    • pooling of blood in legs, reducing venous return
    • dehydration
    • reduction in cardiac output
    • brain ischemia
  19. heat exhaustion typically occurs in hot & humid environments, and is difficult to distinguish from exertional heat stroke, what is heat exhaustion caused by:

    what are the signs and symptoms of heat exhaustion
    • caused by
    • heavy sweating
    • dehydration
    • sodium loss
    • energy depletion

    • signs and symptoms
    • persistent muscle cramps
    • weakness, pallor
    • fainting, dizziness
    • headache
    • hyperventilation
    • nausea, diarrhea
    • loss of appetite
    • decreased urine output
  20. what are the factors leading to exertional heat stroke:

    what are the signs and symptoms:

    what is the treatment:
    • factors leading to EHS
    • inability to get rid of heat can overwhelm the thermoregulatory system
    • core temperature is typically elevated to greater than 104 degrees
    • cellular damage to organs and tissues, including hypothalamus

    • signs and symptoms
    • rapid heart rate (tachycardia
    • hypotension
    • sweating
    • hyperventilation
    • altered mental state
    • diarrhea
    • seizures
    • coma

    treatment: rapid cooling of the body
  21. describe how fitness level can affect the susceptibility to heat illness:

    describe how age can affect the susceptibility to heat illness:
    • fitness level
    • greater fitness level= less susceptibility to heat illness
    • carefully consider fitness before engaging in activity in heat
    • cardiovascular fitness should be the primary focus of conditioning

    • age
    • cardiovascular fxn declines with age
    • decline in cardiac output with age reduces tolerance to heat
  22. for optimal performance of endurance activities in a hot environment what 3 things should be "required":
    • prior acclimatization
    • proper hydration
    • physical conditioning

    • as heat increases, performance declines
    • endurance performance in the heat was consistently found to decrease as predicted by wet bulb globe temperature (WBGT)
  23. describe how anaerobic & strength performance may be impacted by heat exposure:

    how can anaerobic performance be improved in heat exposure:
    • depends on duration of the event and the duration of heat exposure
    • limited exposure in shorter activities may have affect performance at all (100m track)
    • longer events are more likely to affect performance (1500m track)

    • improved by
    • cooling methods
    • hydration
    • limiting of exposure to heat
  24. to avoid declines in performance related heat stress, what are some prevention strategies:

    what are the stages of time course adaptions:
    1-5 days:
    5-8 days:
    3-9 days:
    14 days:
    • acclimation: physiological adaption to an artificial environment
    • acclimatization: physiological adaption to a natural environment

    • time course adaptions
    • 1-5 days: improved regulation/control of cardiovascular system
    • 5-8 days: regulation of body temperature is improved
    • 3-9 days: conservation of sodium chloride (better extracellular fluid volume)
    • 14 days: all adaptions take place
  25. list the 7 adaptions that occur during acclimation and acclimatization:
    • lower core temperature at the onset of sweating
    • increased heat loss via radiation and convection (skin blood flow)
    • increased plasma volume
    • decreased heart rate at a specific workload
    • decreased body-core temperature
    • decreased skin temperature
    • decreased O2 consumption at a giving workload
    • improved exercise economy
  26. list 2 reasons why hydration is important in responding to heat:
    • sweating contributes to evaporative cooling, and heat loss, but it also contributes to dehydration
    • when an athlete's water intake is not optimal, or hypohydration this makes them more susceptible to heat stress, b/c a loss of body mass as little as 1% increases core temperature during exercise
  27. what are the fxn of cold receptors of the body:

    where are cold receptors located:
    • fxn of cold receptors: monitor change and rate of decrease in temperature, signal many different actions to occur
    • located: skin, abdominal viscera & spinal cord

    there are fewer # of cold receptors than heat receptors
  28. describe the acute regulation of physiological responses to cold stress by the hypothalamus:
    • decrease in environmental temperature
    • skin thermal receptors and decreased blood temperature detected by the hypothalamus

    • shivering
    • activate skeletal muscles to produce more heat
    • increased BMR  (basal metabolic rate)

    • sympathetic nervous system
    • piloerection (goosebumps)
    • norephienepherine: skin vasoconstriction
    • small increase in BMR from epinepherine
  29. a condition in which the body's temperature decreases to a point at which normal physiological systems are challenged to maintain normal core temperature is called:

    list and describe the 3 stage of this condition:

    • stage 1
    • body temp drops 1-2 degres below normal
    • loss of ability to perform complex motor tasks (due to increased muscle tension)
    • breathing becomes rapid and shallow

    • stage 2
    • body temp drops 2-4 degrees below normal
    • neuromuscular fxn is affected; slow nerve conduction velocities and blood flow restrictions

    • stage 3
    • body temp drops below 32 degrees C (89.6 F)
    • body systems dramatically shut down
    • example: metabolic and neverous systems
    • cardiac abnormalities occur
    • organs fail
    • brain dies
  30. list the 7 performance responses due to cold:
    • reductions in neuromuscular activity
    • reduction in force production
    • reuction in nerve conduction velocity: summation of nerve impulses arriving at the surface of muscle fibers reduces force production
    • diminished power output
    • decreased heart rate
    • decreased time to peak power
    • exercise- induced brochoconstriction in those with asthma
  31. unlike the case with heat, acclimatization or acclimation to cold typically is related to...

    behavioral changes:
    phsychological adjustments:
    physiological adaptions:
    • behavioral: warming up,learning how to layer and dress properly
    • phsychological: ability to endur the cold
    • physicological: vasodilation in response to high altitude cold exposure, higher basal metabolic rates (eskimos)
  32. describe how heat and cold effect the following:

    VO2 during exercise:
    blood lactate during exercise:
    heart rate during exercise:
    muscle glycogen during exercise:
    • VO2 during exercise: higher in heat than in cold
    • blood lactate during exercise: higher in heat than in cold
    • HR during exercise: higher in heat than in cold
    • muscle glycogen during exercise: higher in cold than in heat
  33. describe the decines in performance at various altiudes...

    700m (2300ft):
    1524m (5000ft):
    2200m (7217ft):

    what are the declines that will be present:
    • 700m: declines being
    • 1524m: declines become more obvious
    • 2200m: declines become more significant

    • present declines
    • imparied oxygen consumption
    • imparied enduracne performanc
    • decline in oxidative metabolism

    WHY: reduced partial pressure of oxygen, more difficult to exchange air flow
  34. compromised delivery of oxygen to target tissues is called:

    what is this condition caused by:
    compromised delivery of oxygen to target tissues is called: hypoxia

    • caused by
    • decreased barometric pressure (hyperbaric)
    • redueced partial pressure of oxygen

    the % of oxygen and other gases in the air are the same regarless of altitude, what varies is the amount of pressure exerted on the molecule of each gas

    as altitude increases, oxygen tension (partial pressure decreases

  35. in addition to hypoxia, as altitude increases what are some other environmental challenges:
    • increased cold with altitude
    • dehydration induced by cold: lower water vapor level than warm air, gradient for water loss from body promotes dehydration
    • increased solar radiation:  a shorter distance for the sun waves to travel, sunburn or skin cancer
  36. compare the partial pressure diffusion gradient of oxygen in the inspired air and in body tissues:

    at sea level:
    at 4300m:
    • at sea level
    • PO2 inspired air = 104 mmHg
    • PO2 in pulmonary artery blood = 40mmHg

    • at 4300m
    • PO2 inspired air = 46mmHg
    • PO2 in pulmonary artery blood = 27mmHg

    • pressure gradient is much less at 4300m
    • decreased airflow
    • decreased muscle O2 consumption
  37. describe the changes in maximal oxygen uptake with decrements in barometric pressure and partial pressure of oxygen:
    • as higher altitude VO2 max is decreasing
    • a negative correlation: relates to how much VO2 is accounted for by change in altitude
    • 81% is accounted for
  38. list the 8 physiological responses to altitude:
    • increased resting heart rate
    • increased blood pressure
    • increased catecholamines (epinephrine)
    • increased pulmonary ventilation
    • increased depth (tidal volume) & rate of breathing
    • decreased maximal oxygen consumption
    • increased in hemoglobin & hematocrit blood concentrations
    • increased blood lactate concentrations
  39. describe the cardiovascular responses to altitude in regards to blood volume in...

    acute altitude exposure:
    chronic altitude exposure:
    • acute altitude exposure
    • decreases plasma volume (25%)
    • respiratory water losses
    • increased urine production
    • increased hematocrit

    • chronic altitude exposure
    • increased blood volume
    • triggers the release of erythropoietin (EPO) from the kidney to stimulate red blood cell production
    • increased blood volume compensates for the lower PO2

    ways to increase RBC: transfusions (illegals), inject EPO (illegal), supplements, train at altitude, hyperbaric chambers
  40. describe the cardiovasuclar response to altitude in regards to cardiac output:
    • cadicac output is increased at rest and during submaximal exercise
    • acute exposure results in a decrease in stroke volume and an increase in HR
    • increase in HR and cardiac output peaks after 6-10 days at altitude
    • decrease in maximal stroke volume and maximal HR
    • decreased sympathetic responsiveness
  41. describe the short duration performance responses to altitude stress:

    describe the long duration performance responses to altitude stress:
    • short duration performance
    • only primarily aerobic activities are affected
    • effect of altitude itself is likely minimal
    • perparation, focus, & other physchological factors contribute
    • shorter races at altitude may increase in performance

    • long duration performance
    • speed is dramatically decreased in endurance running events
  42. list 3 strategies for training for optimal altitude performance:
    • compete within 24 hours of arrival at altitude
    • train at 1500 to 3000 m above sea leve for a minimum of 2 weeks before competeing
    • increased VO2 max at sea level to be able to compete at a lower relative intensity
  43. a pathological condition often requiring medical attention, caused by a reduction in partial pressure of oxygen is called:
    altitude sickness
  44. a special concern of altitude sickness that can lead to pulmonary edema and progress to high-altitude cerebral edema is called:

    what are the symptoms of this condition:
    acute mountain sickness

    occurs in 7% of males and 22% of female recreational athletes

    • sysmptoms
    • headache
    • impaired vision
    • sleep disturbances
    • nausea
    • interrupted breathing patterns (cheyne-stokes breathing)

    • low ventilatory responses to hypoxia, resulting in CO2 accumulation
    • avoid by ascending gradually: no more than 300 m per day above 3000m
  45. life-threatening accumlation of fluids accumulation of fluids in the lungs is called:

    what are the symptoms of this condition:
    • high-altitude pulmonary edema (HAPE)
    • may be related to pulmonary vascoconstriction - induced blood clot formation in the lungs
    • occurs in unacclimatized people who ascend rapidly

    • symptoms
    • shortness of breath
    • persistent cough
    • chest tightness
    • excessive fatigue
    • blue lips and fingernails
    • mental confusion
    • hypersensitivity to light
    • decreased attention and cognition

    treatments: administration of supplemental oxygen and movement to lower altitude
  46. accumulation of fluid in the cranial cavity in regards to high altitude is called:

    what are the symptoms of this condition:
    high altitude cerebral edema

    • symptoms
    • mental confusion
    • lethargy
    • ataxia
    • progressing to coma and death

    • most cases occur above 4300 m
    • cause is unknown

    treatment: administration of supplemental oxygen and movement to lower altitude
  47. what are the short term benefits to acclimatization and acclimation:

    what are the long term benefits to acclimatization and acclimation:
    • short term benefits (3-6 weeks)
    • pulmonary ventilation
    • release of EPO
    • hemoglobin
    • hematocrit
    • plasma volume

    • long term (greater than 3 months)
    • mitochondrial & capillary density
    • pulmonary diffusing capacity
    • mitochondrial enzymes
    • respiratory chain enzymes
    • cardiac output

    live high and train low theory