Chapter 4

Question 1

What is VO2 and VCO2?

Answer 1

VO2: Volume of O2 consumed per minute.

VCO2: Volume of CO2 produced per minute

Question 2

Briefly define the crossover concept?

Answer 2

Describes the relationship between Fat/CHO with exercise intensity as an individual variable.

Question 3

What is the main difference between Respiratory Quotient and Respiratory Exchange ratio?

Answer 3

RER measures pulmonary respiration while RQ measures cellular respiration.

Question 4

Explain what the values of RER mean and how they allow us to determine substrate utilization.

Answer 4

The values of RER go from a range of 0.7-1.0 where .07 means total fat substrate reliance and 1.0 is total carb substrate reliance. This can determine substrate utilization when exercising which describes the shift in the crossover concept.

Question 5

(Relating to the crossover concept)
What are the causes for carbohydrates predominance at higher exercising intensities?

Answer 5

Muscle fiber characteristics and motor unit recruitment as exercise intensity increases. The recruitment of more glycolytic fibers will eventually lead to using carbs as the main source for ATP to maintain contractions.

The catabolic hormone epinephrine also contributes by being a potent activator of phosphorylase which will cause and speed up glycogenolysis from newly recruited glycolytic muscles.

Question 6

True or false.
In the crossover concept, the circulating lactate will stimulate lipolysis as exercise intensity rises.

Answer 6

False, Lactate is an inhibitor of lipolysis which also contributes to the shift from fats to carbs as the main substrate utilized.

Question 7

Explain what SLO, FOG, and FG mean and what it refers to.

Answer 7

SLO - Slow oxidative
FOG - Fast oxidative glycolytic
FG - Fast glycolytic

Refers to muscle characteristics where SLO is also type I, FOG is type IIa, and FG is type IIx.

Question 8

True or false.
At rest there is a high concentration of insulin in the body, and as exercise starts the levels of insulin go down.

Answer 8

True

Question 9

What does HSL stand for and what role does it play in exercise?

Answer 9

Hormone sensitive lipase

When stimulated by epinephrine it will induce lipolysis and even mass lipolysis which increases the utilization of fat as constant exercise gets longer.

Question 10

Fill in the blanks.
Lipolysis is controlled by __________ enzymes which are stimulated by hormones like _______________ (Choose two). This process is also inhibited by the hormone called __________ and circulating ____________.

Answer 10

Lipase

Epinephrine, Growth Hormone, Norepinephrine, Cortisol, and Glucagon

Insulin

Lactate

Question 11

What happens to Insulin levels during exercise? Why is it important for this to occur?

Answer 11

During exercise, Insulin levels decrease.

Although insulin does promote glycogen storage which is important for exercise, it stores glycogen in all cells instead of the specific working tissue.

Question 12

Should an athlete take in a high glycemic load (eat a snack) within an hour before their event? Why or why not?

Answer 12

When an athlete takes in food (namely CHO) shortly before their event, Insulin levels rise which opens up the possibility of rebound hypoglycemia. Because of this, it is better not to eat right before an event.

Question 13

What is happening during rebound hypoglycemia?

Answer 13

When an athlete eats shortly before an event, insulin levels rise which promotes glucose storage in all cells. This takes away potential fuel from the target muscles causing the athlete to feel weak and shaky as they start.

Question 14

When it comes to the crossover concept, what is the main disadvantage of indirect calorimetry?

Answer 14

You can tell what substrate is being used but not the source where it comes from.

Are the carbs coming from muscle glycogen or blood glucose?
Do fats come from free fatty acids or the adiposites?

Question 15

How does each hormone respond to an increase in exercise intensity? What about response to duration?
-Epinephrine
-Norepinephrine
-Growth Hormone
-Insulin
-Cortisol
-Glucagon

Answer 15

All of the listed hormones increase in levels in response to exercise intensity and duration with an exception of insulin which decreases in response to both variables

Question 16

How does blood glucose enter working muscle cells if insulin levels decrease during exercise?

What is the advantage of having a separate exercise signal from the insulin pathway?

Answer 16

As Ca2+ (Calcium) is released during a muscle’s contraction cycle, it activates GLUT4 which co-transports blood glucose into the working muscle cells.

It allows for targeted glucose delivery to working cells as contracting muscles have much higher Ca2+ concentration.

Question 17

What is the argument for exercise as medicine in the diabetic population?

Answer 17

As both type I (not enough insulin) and type II (resistant to insulin) have trouble regulating blood glucose levels, regular exercise can help as contracting muscles pull glucose from the blood through activation of GLUT4.

Question 18

How does the utilization of substrate sources change as exercise duration increases?

Answer 18

At the beginning of exercise, muscles mostly utilize locally stored fuel (muscle triglycerides and muscle glycogen). As duration continues, depleting levels of internal fuel and circulating hormones cause an uptake in externally stored blood fuel (blood glucose from liver and ffa from adiposites).

Question 19

What is the potential issue as duration continues for a very long time at higher intensities?

Answer 19

As the liver only stores about 500kCal of carbs, blood glucose levels may not be able to keep up with the glycolytic uptake in muscles as exercise is prolonged at higher intensities. This may cause a weak, shaky feeling in the exercising individual (called “bonking”).

Question 20

What does Lactate Threshold mean? Is this a good indicator of the potential for endurance exercise?

Answer 20

The point at which blood lactate increases during incremental work.

Yes.

Question 21

What is the difference between Lactate threshold 1 and lactate threshold 2?

Answer 21

Lactate Threshold 1 is the point at which blood lactate increases 1 mmoL over exercise baseline. Where lactate threshold 2 is a rapid disproportionate increase in blood lactate.

Question 22

With VO2 max when would lactate threshold 1 be reached in an average person when exercising?

Answer 22

Around 40-60% VO2 max

Question 23

What would an untrained person’s LT2 be and what would a trained person’s LT2 be?

Answer 23

Untrained - around 50-60% VO2 max
Trained - 70-90% VO2 max

Question 24

Explain why Lactate threshold (2) is a better predictor for endurance performance than VO2 max.

Answer 24

VO2 max is not an endurable or sustainable pace as this is the maximal workload for a person which can be sustained for long periods of exercising, unlike LT.

Question 24

What is Max Lactate Steady State?

Answer 24

The highest workload you can sustain and lactate levels remain constant.

Question 25

What happens physiologically when someone goes past their MLSS?

Answer 25

Lactate and H+ clearance and buffering will not be able to match the production rate resulting in a loss of homeostasis. Once above MLSS blood lactate levels will progressively rise even if the pace is steady.

Question 26

What can be a disadvantage of MLSS testing?

Answer 26

It requires extensive testing of the same patient for multiple visits making the procedure rather tedious.

Question 27

What does OBLA stand for and mean?

Answer 27

Onset Blood Lactate Accumulation
When blood lactate reaches 4mmoL above baseline.

Question 28

True or false.
OBLA tends to coincide with the MLSS of an average Joe.

Answer 28

True.

Question 29

True or False.
MLSS relates only to critical power and critical velocity.

Answer 29

True.

Question 30

How does MLSS relate to critical power and critical velocity in regards to runners and cyclists?

Answer 30

Critical power/velocity is equivalent to MLSS for runners and cyclists when determining running pace or cyclist power output at high workloads without testing for blood lactate.

Question 31

What is the phenomenon called when VO2 slowly increases above critical power reaching VO2 max even though the workload was at a steady state?

Answer 31

The slow component of VO2 max or “Kinetics”

Question 32

What attributes to the slow component of VO2 max?

Answer 32

The recruitment of lactate-producing fibers (Fast glycolytic) and accessory muscles that are used when exercising are consuming O2 too. Such as the lungs and hearts.