Exercise Physiology

Question 1

Index of oxygen consumption, VO2

Answer 1

mL/min/kg At rest:L 3.5ml/min/kg = 1.5 MET

Question 2

The types of fuel being utilized can be determined by Respiratory Quotient (RQ)

Answer 2

RQ= VCO/VO2 (volume of carbon dioxide to the rate of oxygen consumption)

Question 3

RQ for carb is

Answer 3

1.0

Question 4

RQ for fat is variable but averages to

Answer 4

0.7

Question 5

RQ for protein is

Answer 5

0.8 (it is not used as a fuel because we save these for proteins)

Question 6

If we were to measure an RQ of 0.7, that would tell us what?

Answer 6

the person is deriving 100% of energy from fat metabolism not from carbohydrates

Question 7

If we were to measure an RQ of 1.0, what would that tell us?

Answer 7

it would tell us that the person is deriving their energy from carb

Question 8

RQ cannot be measure in vivo - it is measure of what’s going on at the cellular level but the best to do is to measure it

Answer 8

at the mouth- called respiratory exhcnge ratio. We can adjust CO2 by adjusting our breathing rate. If you hyperventilate you increase co2 given off so RER WOULD NOT EQUAL RQ Here. Same for if you hypoventilate

Question 9

So RER (respiratory exchange ratio) = RQ when

Answer 9

the body’s total CO2 content stays constant

Question 10

1 MET = 1 Kcal/kg/hour

Answer 10

e.g. a 70 kg person performing a 3 MET activity for 1 hour would consume approximately 210 Kcal/hr (3x 70)

Question 11

Machine that measures O2 consumption: rate of O2 inspired times the fractional O2 minus rate of O2 expired times the fractional O2 gives you the volume of O2 consumed

Answer 11

ViO2 x FiO2 – ViO2 x FeO2

Question 12

When you start with a person at rest their O2 consumption is miniscule. As you start to increase the intensity of exercise this raises O2 consumption initially then it comes to a steady state

Answer 12

O2 demand = supply. As you continue to increase the intensity, O2 comsumption increases and levels off. But this doesn’t stay like this forever. At some point you intensity will be increased so much and you will see no further increase in O2 consumption. They have reached their max VO2. Their maximal ability to consume oxygen

Question 13

Linear relationship between O2 consumption and exercise intensity. As you increase this for a long time you will reach max VO2

Answer 13

but some people can go to supramax. But this is not supported by aerobic metabolism at this point. VO2 max is the best measure of aerobic fitness

Question 14

What limits maximal O2 consumption?

Answer 14

lungs, heart, vasculature and muscle itself can limit it

Question 15

Linear phase of ventilatory response is when you are doing mild to moderate exercise. You would expect that arterial stuff is stimulating ventilation but you do not see any change in arterial PO2 though mild to moderate. Neither do Arterial PCO2 and pH. Therefore there are other things (joint receptors, muscle receptors, catecholamines)

Answer 15

But then there is a breakpoint where ventilation increases out of proportion to exercise intensity. Here anerobic mechanisms take over as a result lactic acid is made, and pH is decreases (acidosis)==» hyperventilation (helps to resolve the acidosis.

Question 16

In heavy exercise, alveolar O2 will increase because of the hyperventilation. Arterial CO2 decreases (cuz you are breathing it out.

Answer 16

Venous O2 will be decreased and CO will be increased. Does the lung limit O2 consumption? NOOOOOOOO
Hb sat is the same as when you are at rest.

Question 17

Does the heart limit O2 consumption?

Answer 17

CO response to increasing exercise intensity is linear.
CO = HR x SV
HR response is linear increasing - because of increased sympathetic drive to the SA node
SV increases linearly with mild to moderate exercise then it levels off.
SV = EDV - ESV (as exercsise intensity increases, ESV decreases). So the problem is with EDV that causes the leveling…EDV = filling volume time x heart rate. Filling time is reduced…so there are two competing factors: increasing ESV and decreasing EDV so you get a leveling off).

Question 18

So in mild to moderate exercise heart rate and SV are both contributing to the increase in CO

Answer 18

In intense exercise

we rely more on HR to contribute to the increased cardiac output as compared to SV

Question 19

CO distribution in muscle during exercise

Answer 19

Blood flow to skeletal muscel increases 5 fold more than CO becausse we start diverting more O2 to muscles when blood vessels are vasodilating.
There is also vasoconstriction in the gut, spleen and inactive muscles.
Muscles are better at extracting O2 from blood vessels (so venous content progressively decreases). Arterial stays constant

Question 20

Does the CO limit maximal O2 consumption?

Answer 20

If that were true, then if we could deliver more O2 to working skeletal muscle, max oxygen consumption would increase. We can increase O2 delivery to skeletal muscle by blood doping.—adding back RBC to increase Hb and increasing oxygen carrying capacity. if you increase HCT by 10% then the O2 consumption would increase by 10%

Question 21

Does the ability of the skeletal muscle to consume O2 ever limit VO2 max?

Answer 21

not usual in normal people but pts. with COPD, dialysis or pts. on bed rest

Question 22

Answer: it is the maximal ability of the LV to pump blood to the skeletal muscle that

Answer 22

will limit your maximal O2 consumption

Question 23

BP Response depends on

Answer 23

1. muscle mass being used.
   Using large muscles you would expect no increase in Diastolic BP. You would expect Systolic BP to increase. MAP should increase but not greatly…modestly.

Question 24

BP and small muscle groups

Answer 24

you get a greater increase in systolic pressure and greater increase in MAP. It is the amount muscle, the more muscle, the lower the BP

Question 25

BP and large muscle

Answer 25

vasodilation and vasoconstriction in inactive muscle so groups SO TPR will decrease. Using large muscle groups you will get more vasodilation and you BP will not be high

Question 26

BP Response depends on

Answer 26

2. static v. dynamic contraction
   Blood flow substantially increases when performing static contractions up to 30% but as you increase the intensity beyond 30%, the blood flow starts to decline. By 70% MCV- vessels to that muscle occlude so BP increases when performing static (isometric) contractions. Advice: use them rhythmically

Question 27

Anerobic ATP production are fast to turn on in response to need but are not long term

Answer 27

are limited in the capacity to sustain repeated contractions. Myokinase catalyzes ATP to keep the levels up. Creatine phosphate rephosphorylates ADP to make ATP. Glycolysis

Question 28

Aerobic methods include

Answer 28

oxidation of carbs and fatty acids

Question 29

Anerobically provided ATP is important

Answer 29

a. during the transition period from one level of activity to a higher level of activity
b. whenever exercise demands the anerobic threshold of the individual - you don’t use anerobic until you hit the lactate threshold and you increase lactic acid production at high intensity exercises. Ventilatory threshold correlates with the lactic threshold

Question 30

Four factors that influence RER; 1. exercise intensity

Answer 30

At rest 0.85: fat = carb.
At higher intensity, muscles are switching over to use more carbs and less fat
At very high or max intensity: RER increases - muscles are using more carbs than fat. RER also indicates hyperventilation

Question 31

Four factors that influence RER; TIME

Answer 31

With prolonged work, muscle move towards fat > carb. non-depletable fat stores while carbs are depletabl

Question 32

Four factors that influence RER; Prior dietary history

Answer 32

previous carb diet, RER will be higher. low carb = low RER

Question 33

Sources of carbs:

Answer 33

1. blood glucose, 2. liver glycogenolysis and 3. liver gluconeogenesis. As exercise intensifies, muscles take up more and more glucose from blood despite the fact that exercise inhibits insulin release.

Question 34

So with exercise insulin production goes down

Answer 34

but despite this muscle uptake increase and glucose can provide 40% of the energy

Question 35

Arterial blood glucose is well maintained during exercise unless the exercise is performed for a long period of time without

Answer 35

carbohydrate intake. Under these conditions, hypoglycemia can occur and result in fatigue or an inability to continue the exercise after very prolonged exercise

Question 36

Glycogen source in muscle

Answer 36

they use their glycogen stores the greater the intensity of the exercise. Glycogen depletion is sever when exercise is performed to fatigue ~75% VOmax and is the major cause of fatigue at the work rate. Fatigue is likely due to other factors at different exercise intensities

Question 37

Fat source for muscle:

Answer 37

FFA: stress stimulates lipolysis: FFA delivery to skeletal muscle and they get taken up. muscles will oxidize the fat.

What about their lactic acid production between the trained v. untrained dogs? lower in the trained animals because they are not exercising at their VO2 max.
Since the untrained animals will have more lactic acid around and lactic acid is an inhibitor of lipolysis, they must rely more on carbs than on fats for energy.

Question 38

So the choice of substrates for skeletal muscle is fitness level

Answer 38

fit person will use more fats and less carbs than an unfir person and their RER is will be lower. It is a carb-sparing effect: they will spare their glycogen stores and won’t develop hypoglycemia

Question 39

Training: VO2max should change with training

Answer 39

the decline in VO2 with bed rest is much more pronounced than with simple cessation of training or a decrease in habitual activity level
increases in activity increases VO2 max. But it reaches some genetically limited peak.

Question 40

VO2 max is a product of maximal cardiac output x maximal O2 difference (how much O2 is extracted from this blood).

Answer 40

What effect does training have on these two. Maximal ability to extract O2 is highest in the very well trained people, because O2 extraction is diffusion. When they are trained their is an increase in capillary density–>increased surface area. Aeroobic training stimulates mitochondrial synthesis… which will consume more oxygen

Question 41

Training increases maximal cardiac output

Answer 41

because CO: HR x SV. HR does NOT change with training. Training affects maxSV….more blood is ejected. Due to increase in LVVolume. 2. Heart muscle strengthened and can eject more muscle per beat.

Question 42

At sub-maximal work-rate a trained person can perform

Answer 42

any O2 consumption with a lower HR and an higher SV

Question 43

RPP: rate-pressure product = HR x SBP

Answer 43

tells you myocardial oxygen need. Fit individual RPP is lower, heart requires less oxygen, less blood, operating more efficiently and can work in skeletal muscle instead

Question 44

Any given work rate is less stressful after training. As you become more fit, epinephrine

Answer 44

the trained body perceives any given work rate as less stressful as evidenced by lower circulating levels of catecholamines at any given VO2

Question 45

RPE number (Rating of Perceived Exertion) - very, very light—> very, very hard

Answer 45

The number reported on the chart multiplied by 10 will reflect the heart rate at that exercise level.

Question 46

Endurance performance continues to increased with prolonged training despite a leveling off of VO2max

Answer 46

The increase in mitochondrial content is assoc with a marked improvement in endurance capacity and greater resilience on fat as a metabolic fuel at any given work rate.

With long term training (months to years), VO2max may not further increase but the ability to sustain a progressively higher % of VO2 max does, resulting in improved endurance performance. Due to the continued changes in skeletal muscle mitochondria as training occurs

Question 47

How do you increase cardiovascular fitness

Answer 47

• use large muscle groups
• train 3x-5x/week
• 20 - 60 mins of exercise
• intensity must be suffiencient
• apply the RPE scale
• apply the overload principle - in order to improve you have to stop doing the same things over, increase the intensity

Question 48

Stronger muscles

Answer 48

maximally can generate more force, do more work, have more - but normally we don’t ask muscles to work at their maximal effort. A stronger muscle can do the same work at a lesser recruitment level– they will be less fatigued and therefore will be able to do this work longer with more repeats

Stronger muscles favorable impact ADLs, prevent falls, performance in athletics and can impact bone density

Also affected by neural properties: recruitment level and firing frequency

Question 49

Strength Training increases by 2 phenomena in the early and the late:

Answer 49

Neural happens early - you learn how to strength train better
Within a couple of weeks, muscles hypertrophy - because the growth stimulus stimulates actin and myosin filaments (contractile units- crossbridges).
Opposite happens (atrophy) when you don’t use it

Question 50

Is hyperplasia responsible for the hypertrophy?

Answer 50

No, muscle tissue does not undergo mitosis.

Question 51

How to increase muscle strength?

Answer 51

1. exercises for the upper extremities, lower extremities and trunk (8 - 10 exercises).
2. choose weight that can be lifted 8-12 times TO FATIGUE (if you don’t use exercise it to fatigue you will not recruit new motor units - they are the hardest to recruit but they have the greatest capacity to hypertrophy
3. do 1 to 3 sets (do it once, take a break then do it again)
4. exercise 2 - 3x a week (leave 24-36 hrs to let the rate of synthesis exceed the rate of degradation)
5. 1x a week may be sufficient to maintainance
6. apply overload principles - keep upping the ante by increasing the weight

Question 52

Health Implications of exercise

Answer 52

1. enhanced sense of well-being
2. retards loss of work capacity and strength that occur with age
3. better able to accommodate STRESS
4. helps prevent and/or reverse risk factors associated with many chronic dz prevalent in the general population, especially CHD

Question 53

regular physical activity is inversely associated with

Answer 53

1. cardiovascular dz (stroke, PVD)
2. CV dz risk factors (HTN, high TG and low cholesterol, platelet adhesiveness and aggregation, insulin needs and glucose tolerance
3. Colon cancer and reproductive cancers
4. obersity
5. osteoporosis
6. anxiety and depression
7. dementia generally and Alzheimer’s

Question 54

People who exercise regularly even though they have so many ailments etc, have

Answer 54

postpone sickness and death for a long time

Question 55

Exercise and cardiovascular disease have four risk factors

Answer 55

1. smoking
2. hyperlipidemia
3. hypertension
4. sedentary behavior - independent factor

Question 56

Exercise and lipids

Answer 56

regular physical exercise decreases total serum triglycerides (especially those who started with high TG).

• It increases the HDL profile
• It doesn’t decrease total cholesterol but it increases the level of good cholesterol (HDL)

Question 57

Exercise and HTN

Answer 57

regular exercise decreases both systolic and diastolic BP….good for borderline HTN

Severe HTN needs drugs, but should be recommended

Question 58

The higher the physical fitness or physical activity level, the greater reduction in relative risk for both coronary artery disease specifically

Answer 58

and all cardiovascular disease in general. this is a dose responsive curve that the higher the dose, the better the response - dose response effect …the more you exercise, the less is your risk of heart dz

-being moderately exercise is good enough

Question 59

Exercise and Obesity - role of exercise

Answer 59

1. expends calories during and after exercise
2. better match of calorie intake and expenditure
3. maintains Lean Body Mass (good to keep this high because you are always expending energy, even at rest) and so prevents decrease in BMR with weight loss
   Excess mortality increases with increasing BMI

Question 60

Combining exercise with caloric exercise is best

Answer 60

and you might gain muscle

Question 61

Recommendations

Answer 61

1. aim for 500kCal/day deficit (250 kcal decreases intake, 250 kcal increased activity)
2. obese will need greater caloric restriction and greater calorie expenditure
3. avoid sudden, large decreases in caloric intake
4. include resistance exercises to maintain lean body mass
5. expect pattern of fat loss to mirror pattern of fat gain (so don’t do spot exercises)
6. remember small things add up overtime

Question 62

The biggest effect is seen between those who

Answer 62

are completely sedentary and those who perform even minimal amounts of physical activity

Question 63

Current exercise recommendations for health and quality of life

Answer 63

1. a minimum of 30 mins of moderate physical activity, 5 days per week, or a minimum of 20 minutes of vigorous activity, 3 days/week
2. combinations of moderate and vigorous activity can be performed to meet this recommendation
3. alternatively accumulate 150 mins of exercise/week
4. may be broken down into 3 ten minute sessions/day
5. moderate intensity can be 50% VO2 max for healthy adults or as low as 40% VO2 max in patients with low fitness
6. include moderately intense resistance training for major muscle groups
7. recognize the does-response relationship between physical activity and health