Stevens- Exercise Flashcards
how do exercise physiologists estimate “gas exchange”
measure VO2 and production of CO2 through facemask with 2 way valve
____ ml of O2 consumed per kg per minute
3.5
1 MET=
3.5 ml of O2 consumer per kg per min
maximum volume of oxygen that the body can consume during intense, whole-body exercise, while breathing air at sea level
VO2 max
largest VO2 max recorded
97.5 (cyclist) male
best recorded VO2 max for a woman runner
78.6
average female VO2 max age 20-29
35-43 ml/kg/min
average male VO2 max age 20-29
44-51 ml/kg/min
For patients with cardiac disease, a low _______ is the single most powerful predictor of mortality, regardless of the underlying cardiac
diagnosis
VO2 max
VO2 max </= 15 ml/kg/min
cardiomyopathy
PAH w/ incredibly low _____ have high risk of death
VO2 max
PAH VO2 > 10.4 ml/kg/min ____ “risk” of death
low
PAH VO2 < 10.4 ml/kg/min ______ “risk” of death
high
If you can run 4 or 5 laps in 12 minutes, then your VO2 max is on border of _____
30
if you can run 8-9 laps in 12 minutes, VO2 max is around
62-67
in the clinic, used to see cardiorespiratory fitness in ill patients
6 minute walk test
_____ meters on 6 min walk test for VO2 max of 30
1000m
normal subject can walk around ____m in 6 min
600m +
for PAH patients, how many meters in 6 min walk means they are too well to qualify for clinical trials
> 450 m
for PAH patient, how many meters in 6 min means they are too ill to qualify for clinical trials
<150 m
for PAH patient, mortality improves if they can walk > _____ m in 6 minutes
380 m
______ tends to be higher if you are running on flat surfaces and increasing speed than it is if you are increasing incline instead
VO2 max
Fick equation (VO2 max)
VO2= CO (CaO2-CvO2)
under normal conditions, what is the CO
5L per min
CO=
HR X SV
we have about ____ mL of oxygen per dL of blood in the arteries
20
what is the normal CvO2? (how much blood is returned to the heart in the veins)
14.2 mL O2/dL blood
VO2= 5,000 mL/min (20-14.2)
VO2 under resting conditions
O2/Hb curve shifts where during exercise
to the R
CO range that is achieved during exercise
b/t 20-40 L/min
CvO2 during exercise
8.1
what plays a role in VO2 max during exercise
size of person and athletic ability
increase in work = increase in what
CO and VO2
does heart size matter in determining CO
yes
heart size to body weight ratio in humans
0.6%
animal that has the highest heart weight to body weight ratio
endurance animal (dog, husky)
who has the highest heart size to body weight ratio
elite endurance athletes
heart weight to body weight ratio in horses
0.9-1.1%
max CO for horses
400L/min
max heart rate =
220-age
HR reserve should be within ____ bpm of the predicted HR in health individuals
20 bpm
HR reserve=
predicted HR-measured HR
___ is a critical determinant of VO2 max
CO
what determines SV (stroke volume)
preload, contractility, afterlooad
increase work, increase VO2, and then eventually what
it plateaus (VO2 max)
extremely difficult to get an effort that is consistent with ____
VO2 max
determines VO2 max
In normal subjects, the efficiency of _____ is not typically a limiting factor for VO2 max
gas exchange
who will have gas exchange as a limiting factor for VO2 max
patients with lung disease
Exercising muscle utilizes ____ to run aerobic metabolism to generate ATP necessary for muscle contraction
oxygen
what is produced as a byproduct of aerobic metabolism in the muscles that is excreted by exhalation
CO2
which muscle type uses O2 very efficiently (high endurance)
type I (slow oxidative)
this muscle type can have high VO2 maxes, but to a lesser extent (antelopes and gazelles can run fast for a long period of time)
type IIa (fast oxidative)
this muscle type tends to be in outstanding sprinters, but not able to sustain aerobic activity for a long and high level (alligators– very fast but tire quickly)
type IIb (fast glycolytic)
In _____ time period, our muscles have access to sources of ATP that are sufficient to meet early metabolic demands
oxygen deficit
in steady state exercise, _____ from glycolysis is moved into mitochondria for oxidative phosphorylation
pyruvate
____ can also be brought into mitochondria and utilized for ATP generation
palmitate (fat)
At the _____ of exercise, our ATP requirements drop (despite this fact, we continue to have an increase in oxygen consumption that extends for a long period of time)
end
benefit of exercise: our metabolic activity remains elevated for an extended period of time after exercise is completed (what is this known as)
excessive post-exercise oxygen consumption
role of EPOC (excessive post-exercise oxygen consumption)
_____ will extend for a very significant amount of time (think after HIIT workout)
EPOC
in non-steady state exercise, pyruvate is converted to ______ in a process of fermentation (NAD+ produced)
lactate
pyruvate into _____ + ______ through lactate dehydrogenase
lactate and proton (H+)
_____ acid is only generated when pH drops below 4
lactic acid
consequence of fermentation
accumulation of lactate and proton outside of cell
at what percent of VO2 max does lactate accumulate in the blood
almost b/t 75-80%
____ decreases blood pH
lactate
how do lactate and proton give rise to “non-metabolic” CO2
through HCO3-
b/t __ and ___ percent of VO2 max, where is there a non-linear increase in VO2 max
b/t 75-80% (just like with lactate)
minute ventilation increases at ____% of VO2 max
75-80% (same as lactate increase and VCO2)
point at which we can exercise at a pretty comfortable level and sustain effort for some period of time (but past it we can’t sustain for long)
75-80% of VO2 max
exercise decreases venous ____
PO2
exercise increases arterial PO2 and decreases arterial
PCO2 (being blown out)
exercise increases venous ____
PCO2
exercise causes significant increase in _______ O2 difference
Arterial-venous O2 difference
healthy individuals do not _____ with exercise
desaturate
only when there is something wrong with the _____ that you can see a desaturation with intense exercise
lungs
most commonly if someone desaturates with exercise they have ____ disease
lung disease (obstructive, pulmonary vascular disease, interstitial lung disease)
exercise increases ___ and ___ in the blood that will lower pH
CO2 and lactate (in the veins)
We know that with intense exercise, there is increase in anaerobic metabolism due to fermentation that leads to production of lactate and proton; We know that that proton is consumed by bicarbonate to generate CO2; We know that with increasing oxygen consumption, there is a non linear increase of VCO2 at ventilatory threshold
——that is sufficient to blow down CO2, but not sufficient to ______ blood pH
normalize
____ is sensitive to changes in PO2
carotid body
Mechanism that underlies the nonlinear increase in minute ventilation that parallels the nonlinear increase in blood lactate accumulation
carotid body sensing low blood pH (despite high arterial PO2)
resting VE
5-6l/min
tidal volume at resting VE
500 mL
breathing frequency (RR) at resting VE
12-18 bpm
tidal volume during exercise
3,000 mL
respiratory rate during exercise
40-50 bpm
A-a O2 difference < ____mmHg at max (exercise VE)
< 20 mmHg
Consume bicarbonate at the AT (ventilatory threshold/lactate threshold)
______ should drop progressively
“Metabolic acidosis”
PaCO2 (blowing it out due to low pH and high CO2 in veins)
B
A
normal lung VE
<.8
obstructive lung disease VE
> 0.8
normal and cardiac limitation cause _____ in dead space
decrease
pulmonary vascular limitation and interstitial lung disease cause _____ in dead space
increase
