Final Exam

Question 1

thermal balance

Answer 1

Core temperature represents a dynamic equilibrium between factors that add and subtract body heat

Integration of mechanisms that alter heat transfer to periphery regulates evaporative cooling and varies heat production to sustain thermal balance​

Core temperature rises if heat gain exceeds heat loss (i.e., during vigorous exercise in warm, humid environment)​

Core temperature declines in cold when heat loss exceeds heat production​

37 degrees Celsius, 98.6 degrees Fahrenheit ​

Question 2

how is thermal balance controlled and how can exercise alter you ability to control body heat?

Answer 2

Primarily controlled during exercise through sweat, losing the ability to sweat is losing the ability to control our thermal balance​

Trained individual can adapt to heat better due to an increase in plasma volume (allows sweating)

Question 3

hyperthermia (heat stress)

Answer 3

an increase in deep internal body temperature above normal

heat stress challenges body to dissipate excess heat from working muscles during exercises

75% of energy from food is released as heat

Question 4

thermoregulation (heat stress)

Answer 4

ability of body to maintain constant internal temperature

human body’s ability to maintain constant body temperature makes us homeotherms - able to perform in extreme environments

Question 5

how does elevated heat/humidity affect body cooling?

Answer 5

increases challenge by blocking heat dissipation from body

Question 6

thermoregulation

Answer 6

receptors in periphery & CNS detect temperature changes

Question 7

periphery

Answer 7

receptors in & under skin, in peritoneal (abdominal) cavity

Question 8

CNS receptors in:

Answer 8

brain stem

spinal cord

hypothalamus: acts like thermostat

Question 9

hypothalamic control

Answer 9

hypothalamus contains coordinating center for temperature regulation

cannot turn of heat; initiates responses to protect from buildup or loss of heat

Question 10

activation of heat-regulating mechanisms:

Answer 10

thermal receptors in skin provide input to central control center

changes in temperature of blood that perfuses hypothalamus directly stimulate this area

Question 11

circulation

Answer 11

at rest in heat, heart rate and cardiac output increase while superficial arterial and venous blood vessels dilate to divert warm blood to body shell

Question 12

evaporation

Answer 12

effective thermal defense exists when evaporative cooling combines with large cutaneous blood flow

Question 13

hormonal adjustments

Answer 13

sweating produces loss of water and electrolytes, initiating hormonal adjustments to conserve salts and fluids (increased aldosterone and anti-diuretic hormone)

Question 14

fluid loss

Answer 14

Evaporative cooling dissipates heat in exercise, placing a demand on fluid reserves, often producing hypohydration​

Excessive sweating leads to serious fluid loss and reduced plasma volume

Question 15

Competitive cardiovascular demands of exercise in heat:

Answer 15

Muscles require oxygen to sustain energy metabolism​

Arterial blood that divert

Question 16

as we dehydrate…

Answer 16

As we dehydrate, blood thickens.​

Heart works harder, blood loses liquid portion and becomes thicker. Cannot deliver the oxygen to skeletal muscle.​

Stroke Volume increases

Question 17

cardiovascular drift

Answer 17

refers to increase in heart rate that occurs during prolonged endurance exercise with little or no change in workload

increase in heart rate due to dehydration without an increase in intensity

Question 18

consequences of dehydration

Answer 18

Modest fluid loss of 2% body mass adversely affects exercise performance (40-50 minutes in warm environment)​

Augmented hyperthermia​

Increased cardiovascular strain​

Altered metabolic and central nervous system functions​

Increased perception of effort

As dehydration progresses and plasma volume decreases, peripheral blood flow and sweating rate diminish, making thermoregulation progressively more difficult​

Question 19

exercise in heat

Answer 19

submaximal exercise produces lower SV, causing higher HR at all submaximal levels

higher HR in maximal exercise does not offset SV decrease, so maximal cardiac output decreases

maintaining cutaneous and muscle blood flow requires other tissues to compromise blood supply

Question 20

hyperhydration

Answer 20

ingesting “extra” water before exercising in the heat offers thermoregulatory protection

in reality, would have to urinate more often.

Question 21

convection (mechanisms of heat loss)

Answer 21

air blows over surface of skin (or running water as with swimming)

fluid medium to cool

Question 22

conduction (mechanisms of heat loss)

Answer 22

physical contact between 2 surfaces, such as sitting in a cold-water bath to treat heat stroke

gaining heat (or cool) from hot (or cool) surface

Question 23

radiation

Answer 23

molecules in motion emit electromagnetic waves such as the sun

worse at altitude

only 4% of heat loss from radiation in hot environments (vs. 67% at normal temp)

Question 24

evaporation

Answer 24

sweat on skin vaporizes, taking heat with it. Risk of dehydration

convection and evaporation work together

Question 25

Three factors influence total amount of sweat vaporized from skin and/or pulmonary surfaces:​

Answer 25

Surface exposed to environment​ Temperature and relative humidity of ambient air​ Convective air currents about the body

Question 26

Relative Humidity...

Answer 26

most important factor determining effectiveness of evaporative heat loss ratio of water in ambient air to total quantity of moisture that air could contain in humid environment, less convection and evaporation

Question 27

countermeasures (clothing)

Answer 27

Physiologic adaptations can only protect an individual to a certain degree​ Designed to protect against environmental stressors​ Technological advances for both cooling and keeping you warm in microclimates

Question 28

circulatory and metabolic responses to heat stress

Answer 28

Heat increases heart rate & cardiac output (sub-maximal activity, decreased at maximal exercise)​ Redirects circulatory flow to periphery to:​ Dissipate heat​ Cool blood​ Reddens skin​ Flushes complexion

Question 29

body composition (influence of body composition and physical fitness level)

Answer 29

Larger body mass = greater heat production​ Ratio of body volume (generate heat): body surface area (dissipate heat) less favourable in some NFL players​ Body fat insulates, makes heat loss more difficult​ Adipose tissue decreases ability to dissipate heat

Question 30

fitness level (influence of body composition and physical fitness level)

Answer 30

Hot environments require redistribution of blood from core and muscle to periphery to dissipate heat​ Greater fitness = greater cardiac output​ Greater cardiac output = improved ability to redistribute blood from muscle and dissipate heat​ Age:​ More body fat​ Decreased ability to tolerate and dissipate heat

Question 31

korey stringer

Answer 31

core temp reached 108 degrees died from heat stroke brain turned to "mush"

Question 32

heat cramps

Answer 32

muscle cramps that occur when one is exposed to heat triggered by intense exercise characterized by painful, involuntary muscle contractions

Question 33

heat cramps result from

Answer 33

dehydration - lose plasma volume & sodium electrolyte imbalance, specifically whole-body sodium deficit neuromuscular fatigue

Question 34

syncope

Answer 34

fainting or "passing out" often occurs when sitting or standing or after an activity in heat, dizziness or lightheadedness may occur beforehand more common when individuals have not be acclimated or acclimatized need adequate cool down

Question 35

syncope is caused by:

Answer 35

Excessive peripheral dilation​ Pooling of blood in legs, reducing venous return​ Dehydration​ Reduction in cardiac output​ Brain ischemia

Question 36

heat exhaustion

Answer 36

typically occurs in hot & humid environments confused with exertional heat stroke fluid loss decreases SV, decreasing cardiac output

Question 37

heat exhaustion is caused by:

Answer 37

heavy sweating dehydration sodium loss energy depletion

Question 38

exertional heat stroke (EHS)

Answer 38

medical emergency: can lead to death if not treated quickly (temp above 109) body loses its ability to cool itself failure to dissipate heat after intense exercise termoregulatory center is overwhelmed, leading to stroke core temp above 104 degrees

Question 39

exertional heat stroke treatment

Answer 39

rapid cooling of body ice bath, cold compress cool blood where major arteries are (head, neck, armpits, groin area, back of knees)

Question 40

complications of exertional heat stroke

Answer 40

Lactic acidosis​ Acute renal failure​ Rhabdomyolysis (destruction of muscle tissue releasing proteins into blood)​ Bleeding disorders​ Death​ Treatment: immediate, rapid cooling preferably in ice water bath; monitor temperature with rectal thermometer

Question 41

fitness level (factors affecting heat illness)

Answer 41

Greater fitness = less susceptibility to heat illness​ Carefully consider fitness before engaging in activity in heat​ Cardiovascular fitness should be primary focus of conditioning

Question 42

age (factors affecting heat illness)

Answer 42

Cardiovascular function declines with age​ Decline in cardiac output with age reduces tolerance to heat​ Heat acclimatization is possible

Question 43

endurance performance in the heat

Answer 43

as heat increases, performance declines

Question 44

measures to ensure optimal performance

Answer 44

Prior acclimatization (go to where you’re going to be competing) or acclimation (use to environment you’ll be competing in through artificial means) ​ Proper hydration​ Physical conditioning (actual temperature, relative humidity, cloud coverage, and non/prevelance of wind)

Question 45

wet-bulb globe temperature (WGBT)

Answer 45

a composite temperature used to estimate the effect of temperature, humidity, and solar radiation on humans

Question 46

depends on duration of event & duration of heat exposure (anaerobic & strength performance in the heat)

Answer 46

Limited exposure in shorter activities may not affect performance at all (100-m track)​ Longer events are more likely to affect performance (1500-m track) and predispose to heat illness​ Hypohydration does reduce strength, power, and muscular endurance

Question 47

anaerobic & strength performance in the heat improved by:

Answer 47

cooling methods hydration limiting of exposure to heat

Question 48

acclimation

Answer 48

physiological adaptation to an artificial environment

Question 49

acclimatization

Answer 49

physiological adaptation to a natural environment takes bout 2 wks to adapt to altitudes up to 2300 m (7500 ft); after, each 610-m increase requires 1 extra wk adaptions dissipate within 2-3 wks after returning to sea level

Question 50

time course of adaptations: cardiovascular system

Answer 50

1-5 days (plasma volume, reduced heart rate at workload, improved blood flow)

Question 51

time course of adaptations: temperature regulation

Answer 51

5-8 days (sweat rate, sweat at lower temperatures, sweat gland adaptations)

Question 52

time course of adaptations: conservation of sodium chloride

Answer 52

3-9 days (losses from urine and sweat decrease)

Question 53

time course of adaptations: all adaptations

Answer 53

up to 14 days (increased heat loss, decreased core & skin temp, decrease VO2 at workload, improved exercise economy)​ Adaptations lost after 2.5 to 5 weeks out of heat

Question 54

cold receptors in body

Answer 54

Monitor change & rate of decrease in temperature​ Signal many different actions to occur​ Are fewer in number than heat receptors​ Are found in the skin, abdominal viscera, & spinal cord

Question 55

bodys defense against cold

Answer 55

Vasoconstriction of blood vessels in skin​ Decrease sweating​ Release thyroid hormones to increase metabolism and heat production​ Shivering of skeletal muscle​ Epinephrine: increase metabolism; norepinephrine: increase vasoconstriction​ Hair stands up to increase insulation (less effective in humans)​ Decreased blood flow to skeletal muscle (unless physical activity increases)​ Curling up to preserve core heat, seeking shelter, finding heat sources, eating, putting on additional clothing

Question 56

hypothermia

Answer 56

decrease in bodys temperature to a point that normal physiological function is impaired

Question 57

hypothermia stage 1

Answer 57

body temp 1 to 2°C below normal​ Loss in ability to perform complex motor tasks​ Breathing becomes rapid & shallow

Question 58

hypothermia stage 2

Answer 58

body temp 2 to 4°C below normal​ Neuromuscular function is affected

Question 59

hypothermia stage 3

Answer 59

body temp below 32°C​ Body systems shut down, organs fail, brain dies

Question 60

afterdrop

Answer 60

the continued fall of deep body temperatures during rewarming after hypothermia

Question 61

performance responses to cold

Answer 61

Reductions in neuromuscular activity​ Reduction in nerve conduction velocity, or rate that neural impulses travel to muscle fiber Reduction in force production (except possibly eccentric actions, but only with mild cooling)​ Diminished power output​ Decreased heart rate at given workload​ Decreased time to peak power

Question 62

physiological adaptations of acclimatization/acclimation

Answer 62

vasodilation in response to high altitude cold exposure higher basal metabolic rates (Eskimos)

Question 63

barometric pressure (Pb)

Answer 63

760 mmHg at sea level

Question 64

partial pressure of oxygen (PO2)

Answer 64

portion of Pb exerted by oxygen 0.2093 x Pb ~ 159 mmHg at sea level reduced PO2 at altitude limits exercise performance

Question 65

hypobaria

Answer 65

reduced Pb seen at altitude results in hypoxia (partial pressure of O2 is reduced)

Question 66

stress of altitude

Answer 66

Altitude’s physiologic challenge comes directly ​ from decreased ambient Po2​ O2 transport cascade refers to progressive changes in environment’s O2 pressure and bo

Question 67

other challenges with altitude

Answer 67

Increased cold with increased altitude​ Dehydration induced by cold (which has lower water vapor than warm air, increases loss of water - particularly when paired with physical exertion)​ Increased solar radiation (decreased distance and thinner atmosphere above individual) – vitamin D production, sunburn, DNA damage, skin cancer

Question 68

cardiopulmonary responses

Answer 68

Hyperventilation from reduced arterial Po2 reflects the most important and clear-cut immediate response of native low-landers to altitude exposure Resting blood pressure increases in early stages of altitude adaptation​ Increases in H.R. and Q

Question 69

fluid loss

Answer 69

Ambient air in mountainous regions remains cool and dry, allowing body water to evaporate as inspired air becomes warmed and moistened in respiratory passages​ Respiratory water loss, urine production​ (Lose up to 25% plasma volume​) Fluid loss becomes pronounced for physically active people because of large daily total sweat loss and exercise pulmonary ventilation

Question 70

catecholaimne response

Answer 70

Sympathoadrenal activity progressively increases over time during rest and exercise with altitude​ increased BP & HR at altitude relate to steady rise in plasma levels and excretion rates of epi increased sympathoadrenal activity contributes to regulation of BP, vascular resistance, & substrate mixture during short & long-term hypobaric exposures

Question 71

hematologic alterations

Answer 71

Increase in blood’s oxygen-carrying capacity provides important longer-term adjustment to altitude exposure​

Question 72

two factors account for hematologic alterations

Answer 72

initial decrease in plasma volume increase in erythrocytes and hemoglobin synthesis

Question 73

cellular adaptations

Answer 73

Remodeling of capillary diameter and length with formation of new capillaries​ Improved microcirculation to reduce oxygen diffusion distance between blood and tissue​ Increased myoglobin (augments O2 storage)​ Small increase in mitochondrial number and concentration​ Slight right shift of oxy-hemoglobin dissociation curve (more unloading)​ Increased 2,3-DPG concentration​ Increased EPO

Question 74

body mass & composition

Answer 74

Basal metabolic rate ​ Increased Thyroxine secretion​ Increased Catecholamine secretion​ Must increase food intake to maintain body mass​ More reliance on glucose versus fat​ Anaerobic metabolism= increased lactic acid​ Lactic acid production decreases over time​ No explanation for lactate paradox

Question 75

sport performance

Answer 75

Aerobic exercise performance affected most by hypoxic conditions at altitude​ VO2max decreases as a percent of sea level VO2max ​ Given task still has same absolute O2 requirement​ Higher sea-level VO2max ---> easier perceived effort lower sea-level VO2max ---> harder perceived effort

Question 76

live low, train high (LLTH)

Answer 76

has little to no enhancing benefit Wilbur 2007 - small # of significant improvement in blood parameters, aerobic capacity, or work performance

Question 76

blood doping

Answer 76

Increasing the number of red blood cells either by transfusion or by the use of erythropoietin (EPO) to boost the production of red blood cells; typically not permitted and of unknown efficacy​ 450-1800 ml of blood taken usually 12-16 weeks prior to event​ Re-infused about a week before event