Ex Phys Ch. 13

the combo of respiratory water loss and increased urine production can reduce total plasma volume by up to ___%. Initially, the result of the plasma loss is a(n)___. This adaptation does what?

25 increase in hematocrit allows more O2 to be delivered to the muscles for a given Q.

Why is cool, dry air at altitude a problem? (2)

-The low water vapor pressure of air promotes evaporation of moisture from the skin (or clothing) surface, because of the high gradient between skin and air, and can lead quickly to dehydration. -a large vol of water is lost through respiratory evap due to a combo of a) large vapor pressure gradient b/w warmed air leaving mouth and nose and the dry air in the env't and b) an increased respiration rate at altitude

why does intensity of solar radiation at altitude increase? (2)

1) light travels through less atm before reaching earth --> less of sun's radiation (UV rays) is absorbed by atm at higher altitudes 2) low water vapor in air increases radiant exposure since atm water normally absorbs a substantial amount of sun's radiation

what are the effects of respiratory alkalosis? (2)

1- causes oxyHb curve to shift left 2- helps keep rise in ventilation caused by hypoxic drive from increasing even further

What can athletes who normally train at sea level but must compete at altitude do to prepare most effectively for competition? (2 options)

1- compete ASAP after arriving at altitude, and certainly within 24 h of arrival. 2- train at higher altitudes for a minimum of 2 weeks before competing

VO2max decreases approx ___% for every ___ increase in altitude above 1500 m. Rate of decline may become even ___ at very high altitudes

10 1000 m steeper

VO2max decreases little until atmospheric PO2 drops below ___. This decline generally begins at an altitude of about ___- the elevation of denver and albuquerque.

131 mmHg 1500 m

extended training for optimal performance at altitude requires an elevation between __ and __. ___ capacity is reduced during the initial days of altitude. For this reason, when first reaching higher altitudes, athletes should reduce workout intensity to between ___-___% of sea level intensity, gradually working up to full intensity within ___-___

1500-3000 m work 60-70% 10-14 days

at any elevation, air contains ___% O2, ___% N, and ___% CO2. Only the ___ of these gases change

20.93% 79.04% 0.03% partial pressures

Within the first ___ after arrival at a high elevation, the blood's EPO concentration increases; it then continues to increase for ___-___. Although blood EPO concentrations return to baseline in about ___, the ___(increased RBCs) may be evident for ___ or more.

3 h 2-3 days 1 month, polycythemia 3 months

Within __ or ___ at 4000m, the increased resting ventilation rate levels off at a value about ___% higher than at sea level. Submax exercise ventilatory rate also plateaus at about ___% higher but over a(n) ___ time frame. Increases in ventilation during exercise remain ___ at altitude and are more pronounced at ___ exercise intensities

3 or 4 days 40% 50% longer elevated higher

Generally, about ___ are needed for full acclimation to even moderate altitude. For each additional 600 m altitude increase, another ___ is needed on average. All of the beneficial effects of acclimation/acclimatization are lost within ___ of return to sea level

3 weeks week a month

A rule of thumb at altitude is to consume at least ___-___ of fluid per day; however, must be tailored to individual needs.

3-5 L

Some athletes can choose to train at higher altitudes for a minimum of 2 weeks before competing to optimize performance. However, 2 weeks isn't even sufficient for total acclimation. Total acclimation would require a minimum of ___-___, and usually even longer.

3-6 weeks

The average hematocrit at sea level:

45-48%

People with VO2max values of ___ at sea level would be unable to exercise, or even to move, near the peak of Mt Everest bc their VO2max values at that altitude would be too low to sustain their ___. Enough O2 would be consumed to barely meet their ___ requirements

50 ml/kg/min body tissues resting

During 6 weeks of exposure to the Peruvian altitude, sea level residents have shown remarkable increases in their hematocrit levels, up to an average of ___%

59%

what is altitude?

> 1500m/5000 ft elevation

What causes AMS?

A maladaptive response to altitude. The peripheral chemoreceptors don't sense the decreased arterial PO2 and fail to hyperventilate. This causes CO2 to build up which causes H+ to build up as well, reducing the pH and putting the body in a state of acidosis.

The concentration of ___ increases in RBCs with acclimation, which shifts the oxyHb dissociation curve to the right. This would favor ___ of O2 at the tissues, but this effect opposes the loading benefit of the ____, a leftward shift. The net effect of both mechanisms is variable

DPG unloading respiratory alkalosis

what drawback does competing ASAP after arriving at altitude, and certainly within 24 h of arrival have when preparing for competition?

Doesn't provide the beneficial affects of acclimation, but the altitude exposure is brief enough that the classic symptoms of altitude sickness are not yet totally manifest

Hypoxic conditions stimulate the renal release of ___, which increases RBC production in bone marrow. More RBCs means more ___. Although plasma volume ___ initially, which helps concentrate the ___, it eventually returns to ___. Normal plasma volume plus additional RBCs increases the total ___. All these changes increase the blood's ___.

EPO Hb decreases, Hb, normal blood volume Oxygen-carrying capacity

events that unfold after a week at altitude: (1)

EPO that was released immediately causes polycythemia

As the volume of erythrocytes increases, so does the blood's ___ content (and concentration, after an initial ___)

Hb decline

In summary, hypobaric conditions significantly limit ___ to the muscles, reducing the capacity to perform ____-intensity or ___ aerobic activities

O2 delivery high, prolonged

Iron deficiency may prevent the increase in ___ that occurs progressively over the first 4 wks or so at altitude. Therefore, consumption of iron rich foods and perhaps even iron supplements is recommended before an during altitude exposure

RBC production

max HR may be somewhat lower at high altitude as a consequence of a decrease in the response of the ___ activity,

SNS

upon ascent to altitude, the ___ is stimulated releasing ___ and ___, the main hormones that alter cardiac function. The increase in ___ in particular persists for several days of acute altitude exposure

SNS epinephrine, norepinephrine norepinephrine

multiple studies have now shown a benefit of living at low altitudes but training at high altitude for increasing sea level ___ or improving sea level ___ performance in elite endurance athletes. These improvements have been linked to an increase in the ___ of the blood

VO2max, aerobic O2-carrying capacity

As VOmax declines on arrival at altitude, competition at any given pace will be performed at:

a lower percentage of VO2max

When living and training at altitude, athletes are faced with the problem that the intensity of training is reduced because ___ capacity and ___ function are reduced at altitude. Thus, although athletes ___ certain physiological benefits from being at altitude, they ___ training adaptations associated with higher intensities of training. One way to get around this problem is to have athletes ___ at moderate altitude but ___ at low altitude, where training intensity is not compromised

aerobic, cardiorespiratory gain, lose live, train

The thinner air at altitude provides less ___ to athletes' movements.

aerodynamic resistance

what can several weeks of intense training at sea level to increase VO2max do to allow optimal performance?

allows athlete to compete at altitude at a lower relative intensity (%VO2max) than if they had not trained aerobically.

does altitude training improve sea level performance? What's the argument FOR altitude training?

altitude training evokes substantial tissue hypoxia which is though to be essential for initiating the conditioning response. Also, the altitude-induced increase in RBC mass and Hb content improve O2 delivery upon return to sea level. Although the latter changes are transient, only lasting a few days, in theory this should still provide an advantage for the athlete.

___ activities that last less than ___ are generally not impaired by moderate altitude and can sometimes be ___. Such activities place minimal demands on the ___ system and ___ metabolism. Instead, most of the energy is provided through the ___, ___, and ___ systems

anaerobic 1 min improved oxygen transport aerobic ATP, PCr, glycolytic

consuming adequate calories to support exercise and recreational activities is important, and climbers should be instructed to eat more calories than their ___ suggests.

appetite

the amount of O2 delivered to the muscles by a given volume of bloodis limited at altitude because of the reduced ____. A logical means to compensate for this is to increase the ____ of blood delivered to active muscles.

arterial PO2 volume

At altitudes b/w 1500 and 5000 m the decreased VO2max is primarily due to the reduced ___; at higher elevations, a decreased ___ further limits VO2max.

aterial PO2 Qmax

After a few days at altitude, what do the muscles start doing? What does this do to the demand for increased Q? Why?

begin extracting more O2 from the the blood (increasing a-v O2 diff) decreases the demand for increased Q VO2 = Q X a-vO2 Diff

The reduction in plasma volume during acute altitude exposure reduces total ___, thus reducing ___ and ___. But with acclimatization, as plasma volume ___ over several weeks at altitude and as RBCs continue to ___, ___ increases. It ___ return to sea level values

blood volume, submax and max Q increases increase max Q does not

In ppl who maintain their body weight at altitude there's an increased reliance on ___ for fuel, both at rest and during submax exercise. Why is this adaptation beneficial?

carbs glucose yields more energy than fats or proteins per liter of O2

While a "___ effect" on performance is more difficult to prove, athletes who train at altitude routinely have a difficult time maintaining their sea level training ___ or ___ .

ceiling intensities, volumes

Endurance athletes w/ high VO2max at sea level have a(n) ___ at altitude if everything else is equal.

competitive advantage

Appetite ___ at altitude, and ___ food intake often accompanies this. This ___ energy consumption coupled with ___ metabolic rates can lead to daily energy deficits of up to ___, resulting in ___ over time.

decrease, decreased decreased, increased 500 kcal/day weight loss

at maximal or exhaustive work levels at higher altitudes, max SV, max HR, and Q are all ___

decreased

When submax exercise is performed during first few hours at altitude, SV is ___ compared to sea level values (attributable to the ____). What does HR do to respond to this? How does this effect Q? Is this an efficient way to ensure sufficient O2 delivery to the active tissues for prolonged periods?

decreased decrease in plasma volume increases disproportionately to compensate for lower SV and to increase Q slightly causes a slight increase in Q no

In a study of climbers experiencing 4-6 weeks of chronic hypoxia on expeditions, muscle fiber cross-sectional area ___, thus ___ total muscle area. Capillary density in the muscles ___, which allowed __ blood and O2 to be delivered to the muscle fibers.

decreased, decreasing increased, more

VO2max ___ as altitude increases.

decreases

Total muscle mass ___ after a few weeks at altitude, as does total body weight. Part of this decrease is from ___ and ___ suppression. However, there is also ___ in the muscles

decreases dehydration, appetite protein breakdown

With a decreased ___ to move O2 from the blood into the muscles, coupled with the reduction ___, it's apparent why both VO2max and submax aerobic performance are hindered at altitude

diffusion gradient max Q

Explain acute mountain sickness:

disorder characterized by symptoms such as headache, nausea, vomiting, dyspnea, and insomnia. These symptoms an begin 6-48 h after arrival and are most severe on days 2-3.

Because VO2max is reduced a certain percentage, people with larger aerobic capacities can perform a standard work task with less perceived ___ and with less ___ and ___stress at altitude than those with a lower VO2max

effort CV, respiratory

continued exposure to high altitude triggers the release of ___ from the kidneys; what is this responsible for? What does this do? What's the bummer about this adaptation?

erythropoietin (EPO) responsible for stimulating erythrocyte production this increases to total number of RBCs and creates a greater total blood volume, which allows the person to partially compensate for the lower PO2 experienced at altitude. it's slow, taking weeks to months to fully restore red cell mass.

Over a period of weeks at altitude what happens to the diminished plasma volume?

eventually returns to normal if adequate fluids are ingested.

Other muscle adaptations include decreased ___, increased ___, and decreased ___ activities

fiber area capillary supply oxidative enzyme

It may seem counter productive to increase fluid intake when the decrease in plasma volume is taking place to help "pack" RBCs. However, dehydration can negatively alter the body water balance among ___, so staying well hydrated and allowing the natural decrease in plasma volume to occur is sound advice.

fluid compartments

The increased BMR must be balanced by an increased ___ to prevent body weight from decreasing, a common occurrence during first few days at altitude because ___ declines as well

food intake appetite

However well people acclimate to conditions at high altitude, they never ___ compensate for the hypoxia.

fully

The percentage of total blood volume composed of erythrocytes:

hematocrit

increased ventilation at altitude acts a lot like ___ at sea level. How?

hyperventilation amount of CO2 in alveoli is reduced so more flows out of the blood (where its pressure is high) and into the lungs to be exhaled. this "blowing off" of CO2 causes causes blood PCO2 to fall and blood pH to increase, a condition known as respiratory alkalosis

3 major conditions that make altitude "different"

hypobaric conditions cool, dry air solar radiation

why are the 3 major conditions that make altitude "different" a big deal?

hypobaric conditions: decreases PO2 in lungs and pulmonary diffusion of O2 and transport to muscles cool, dry air: have to work harder to humidify inhaled air solar radiation: UV at altitude in increased and radiant heat

low PO2 in air: resulting low PO2 in blood:

hypoxia hypoxemia

Why do people experience headaches due to AMS?

hypoxia causes dilation of cerebral blood vessels causing stretching of pain receptors

under resting conditions, pulmonary diffusion does not limit exchange of gases b/w alveoli and blood. How is this known?

if this did limit gas exchange, the values of alveolar and arterial PO2 would differ substantially, but they are about the same

Overall oxygen delivery capacity is ___ with acclimatization but not to the extent needed to achieve seal level ___ values

increased VO2max

pulmonary adaptations to altitude:

increased ventilation within seconds of exposure to high altitude, both at rest and during submax exercise.

given hypoxic conditions at altitude, and because any fixed amount of work at altitude represents a higher percentage of VO2max, we would expect anaerobic metabolism to be ___. If this occurs, what would we expect to see in regard to La+?

increased. La+ production to increase at any given work rate above LT

After a person lives at 4000 m for about 6 mo, total blood volume ___ by about ___%, not only as a result of altitude-induced stimulation of ___ but also because of ___.

increases 10 erythrocyte production plasma volume expansion

During the first 2 weeks at altitude, the number of circulating erythrocytes ___. The lack of O2 at altitude does what to make this happen?

increases stimulates the renal release of EPO.

What does the ascent to altitude do to BMR? What's this possibly due to?

increases BMR increases in [thyroxin and catecholamine]

successful acclimation and acclimatization to high altitude depend on adequate ___ stores in the body.

iron

how does the body offset respiratory alkalosis?

kidneys increase excretion of bicarb in urine, reducing blood's buffering capacity. More acid remains in blood and alkalosis is minimized.

events that unfold 2-3 days at altitude: (2)

kidneys will excrete more HCO3 and reabsorb more H+ increased DPG in the Hb mols will cause a right shift

Studies conducted on endurance-trained runners in the late 1960s indicated that the decrement in VO2max when they first reached high altitude improved ___ for the duration of their exposure to hypoxia. Aerobic capacity remained ___ for up to 2 months at altitude. Although the runners who previously had been exposed to altitude were more ___ of hypoxia, their VO2max values and running performance ___ significantly improved with acclimation.

little unchanged tolerant were not

there appear to be benefits from ___ at moderate altitudes but going to lower elevations to maximize training ___

living intensity

does altitude training improve sea level performance? What's the argument AGAINST altitude training?

living and training at moderate and high altitudes often causes dehydration and blood volume and muscle mass loss. These and other side effects tend to diminish the athletes' fitness and their motivation and tolerance for intense training. Sustained and short-term power outputs at max intensity are reduced under hypoxic conditions

Activities of ___ duration that place considerable demands of the ___ and ___ by tissues are those most severely affected by the hypoxic conditions at altitude.

long O2 transport and uptake

What primarily limits performance at altitude?

low PO2

With longer exposure to altitude, the [La+] in muscles and venous blood at a given intensity of exercise (including max exertion) is ___, despite the fact that muscle VO2max does not change with adaptation to altitude.

lower

muscles' inability to meet exercise demands at high altitudes may be related to a decrease in their __ and their ability to generate ___

mass ATP

Several weeks at altitudes above 2500 m reduce the ___ potential of muscle, although this may not occur at lower elevations. Both ___ and ___ of the leg muscles are significantly reduced after 4 weeks at altitude. This suggests that, in addition to receiving less O2, muscles lose some of their capacity to perform ___ and generate ___.

metabolic mitochondrial function glycolytic enzyme activity oxidative phosphorylation, ATP

Is there a difference in the rate of VO2max decline upon arrival at altitude between men and women?

no

Does artificial "altitude" training work?

not usually. Hypobaric apartments may help a little if the athlete literally spends every waking moment in them, but usually the dose is too small

The increase in HR and Q peaks after about 6-10 days at high altitude, after which Q and HR during a given exercise bout start to ___

peaks decrease

immediate events at altitude: (2)

peripheral chemoreceptors signal an increase in respiratory rate respiratory alkalosis will cause left shift in curve (decreased PCO2)

Why does ventilation increase immediately and persistently? What is this associated with primarily?

peripheral chemoreceptors stimulated by low PO2, signals are sent to brain to increase breathing. associated with increased tidal volume and an even greater increase in respiratory rate

explain the whole process of persistent hyperventilation leading to a decreased exercise capacity:

persistent hyperventilation, decreased PaO2, decreased PCO2, and decreased Hb saturation causes a decreased PO2 gradient at the muscle which decreases gas exchange at the muscle, which decreases exercise capacity.

The decrease in SV at max intensities is directly related to the decrease in ___

plasma volume

Blood Hb concentration tends to increase ___ with increases in the elevation at which ppl reside. These adaptations improve ___ of a fixed volume of blood

proportionately O2 carrying capacity

the lower atm pressure means lower PO2 in inspired air, which limits:

pulmonary diffusion of O2 from lungs and transport to tissues

One of the most important adaptations to altitude is an increase in ___, both at rest and during exercise.

pulmonary ventilation

How does Q react to altitiude at rest, during submax exericise, and during max?

rest- increases submax- increases max- decreases

At altitude, body has tendency to lose fluids through the ___ (insensible water loss), the ___ system, and the ___. This water loss is exaggerated with ___ as sweat evaporation increases from the wetted skin to the relatively dry air. These avenues of fluid loss dramatically increase the risk of ___, and one should pay careful attention to staying ___

skin, respiratory, kidneys exercise dehydration hydrated

because of the many adaptations that occur during acclimation to altitude, this lack of improvement in aerobic capacity and performance was ___. Perhaps these trained subjects had already attained ___ training adaptions and were unable to further adapt in response to altitude exposure. Or perhaps the reduced ___ of altitude made it more difficult for them to train at the same intensity and volume as at sea level. Both possibilities have some merit based on available literature.

unexpected max PO2

how does ventilation at altitude compare to that at sea level?

ventilation is higher at rest and a given submax intensity at altitude, but at max exercise it's about the same

explain plasma volume reaction to altitude: what is this a result of? (2)

within the first few hours of arrival at altitude, plasma volume begins to decrease, and the decline reaches a plateau by the end of the first few weeks. decrease in plasma volume is result of respiratory water loss and increased urine production

While ___ capacity improves with altitude acclimation, the decrease in ____ with initial exposure to altitude does not improve much over several weeks of exposure and typically never returns to sea-level values

work VO2max