Ch.4 - Exercise Metabolism

Question 1

oxygen deficit

Answer 1

applies to the lag in oxygen uptake at the beginning of exercise

specifically, the oxygen deficit is defined as the difference between oxygen uptake in the first few minutes of exercise and an equal time period after steady state has been obtained.

Question 2

** just a fact:

in the transition from rest to light or moderate exercise, oxygen uptake increases rapidly, generally reaching a steady state within one to four minutes

Answer 2

.

Question 3

** just a fact:

after a steady sate is reached, the body’s ATP requirement is met via aerobic metabolism

Answer 3

.

Question 4

oxygen debt

Answer 4

the elevated oxygen uptake (above resting levels) following exercise.

Question 5

gluconeogenesis

Answer 5

the process of glucose synthesis from noncarbohydrate sources

only about 20% of the oxygen debt is used to convert the lactate produced during exercise glucose

Question 6

excess post-exercise oxygen consumption (EPOC)

Answer 6

The amount of oxygen our body consumes following a bout of exercise that is in excess of the pre-exercise oxygen consumption baseline level.

Essentially, our body uses more oxygen after exercise than before exercise, and we expend more calories during our recovery from exercise than we do before exercise.

epoc is greater during high-intensity exercise because:

• heat production and body temperature are higher
• pc is depleted to a greater extent and more O2 is required for its resynthesis
• higher blood lactate levels mean more O2 is required for lactate conversion to glucose in gluconeogensis
• epinephrine and norepinephrine levels are much higher

Question 7

factors contributing to EPOC

Answer 7

1. resynthesis of pc in muscle
2. lactate conversion to glucose
3. restoration of muscle and blood oxygen stores
4. elevated body temperature
5. post-exercise elevation of hr and breathing
6. elevated hormones

Question 8

intense exercise lasting more than 20 sec relies more on what glycolysis?

Answer 8

anaerobic

to produce much of the needed ATP

Question 9

high-intensity events lasting longer than 45 sec use a combination of the what?

Answer 9

ATP-PC system, glycolysis, and the aerobic system

to produce the needed ATP for muscular contraction

Question 10

energy to perform prolonged exercise (ex more than 10 mins) comes primarily from what metabolism?

Answer 10

aerobic

Question 11

incremental exercise tests

aka

graded exercise tests

Answer 11

often employed by physicians to examine patients for possible heart disease and by exercise scientists to determine a subjects cardiovascular fitness

usually conducted on a treadmill or cycle ergometer

Question 12

maximal oxygen uptake

aka

VO2 max

Answer 12

the maximal capacity to transport and utilize oxygen during exercise is considered by may exercise scientists to be the most valid measurement of cardiovascular fitness

Question 13

anaerobic threshold

aka

lactate threshold

Answer 13

the point of a systematic rise in blood lactate during incremental exercise because of the obvious link between anaerobic metabolism and the appearance of lactate

Question 14

mechanisms to explain the lactate threshold during incremental exercise

Answer 14

1. low muscle oxygen
2. accelerated glycolysis due to epinephrine
3. recruitment of fast-twitch fibres
4. reduced rate of lactate removal

Question 15

just a fact**

oxygen uptake increases ina linear fashion during incremental exercise until VO2 max is reached

the point at which there is a sudden increase in the blood lactate concentration during an incremental (graded) exercise test is termed the lactate threshold

Answer 15

.

Question 16

respiratory exchange ratio (R)

Answer 16

a noninvasive technique that is commonly used to estimate the percent contribution of carbohydrate or fat to energy metabolism during exercise

is the ratio of the volume of carbon dioxide produced (VCO2) to the volume of oxygen consumed (VO2)

**the respiratory exchange ratio is the ratio of carbon dioxide produced to the oxygen consumed (VCO2/VO2)

Question 17

what causes the shift from fat to carbohydrate metabolism as the exercise intensity increases?

Answer 17

1. recruitment of fast fibers and

2. increasing blood levels of epinephrine

Question 18

free fatty acids (FFAs) and lipases

Answer 18

triglycerides are broken down into FFAs and glycerol by enzymes called lipases.

Question 19

lypolysis

Answer 19

is a slow process, and an increase in fat metabolism occurs only after several minutes of exercise

Question 20

what is used as the major fuel source during high intensity exercise?

Answer 20

carbohydrates

Question 21

during prolonged exercise, what is there a gradual shift of?

Answer 21

a gradual shift from carbohydrate metabolism toward fat metabolism

Question 22

the cori cycle: lactate as a fuel source

Answer 22

during intense exercise, lactate is formed in muscle fibres.

the lactate formed in muscle can then be transported via the blood to the liver and converted to glucose by gluconeogensis