Energy metabolism 1

Question 1

For very high force concentrations lasting 1-2 s, the initial energy source is from…

Answer 1

ATP
(compared to glycolysis, creatine phosphorylation, phosphocreatine stores)

Question 2

When are phosphocreatine stores broken down?

Answer 2

when talking about exercise of 2-20 seconds.

Question 3

After what period of time does maximal dynamic exercise become predominantly aerobic?

Answer 3

2 min (>800 m) , >60% aerobic

Question 4

Phosphocreatine + anaerobic glycolysis =
Oxidative metabolism =
..phosphorylation

Answer 4

1. substrate-level
2. oxidative

Question 5

Which fiber types exist in humans? characteristics?

Answer 5

> T1: slow-twitch (red: aerobic: fatigue-resistant)
T2: fast-twitch (white: fast, lots of force, easily fatigued)
T2X: fastest, T2A: less fast

Question 6

Which fiber types are used when weight lifting? (using maximal force)

Answer 6

All

Question 7

Why are some fibers red and some white?

Answer 7

White vs red appearance depends on capillarization. Mito density is also higher in red fibres vs white.

Question 8

Weight lifting performance is not determined by a limiting energy availability, because..

Answer 8

Weight lifting requires activation of all muscle types at same moment, which requires technique, skills, coordination. Performance not determined by a limiting energy availability.

Question 9

A sprinter uses the…. metabolism

Answer 9

anaerobic metabolism (= phosphagen (ATP + Pcr) and glycolytic)

Question 10

Resynthesis of PCr requires

Answer 10

energy (ATP).

Question 11

: The complete resynthesis of PCr after very high intensity exercise normally takes (time):

Answer 11

about 4 minutes (relatively short time)

Question 12

Phosphocreatine resynthesis during recovery from exercise is inhibited by:

Answer 12

a) an excess of creatine
b) hyperventilation
c) an excess of oxygen
–> a lack of oxygen
e) submaximal muscle contractions

Question 13

Glycolytic system:
Glycogen will be broken down with A
-> B

Answer 13

glycogenolysis
-> glycolysis

Question 14

Glycolytic system:

Answer 14

 Reach max not until after 5 s
 Maintained up to 30 sec
 Rate lower (2x), size higher (4x) compared to Pcr: power output lower

Question 15

Fatigue in exercise <10s:

 Max power reached after X
 Performance depends on X achieved early in exercise:
- A
- B
 X implicated
A, B, C

Answer 15

 Max power reached after 3-4 s
 Performance depends on max speed achieved early in exercise:
PCr availability (size of store): important!
Maintenance of force pH depended
 Metabolites implicated
Pi, H+ accumulation, lactate

Question 16

Creatine is stored in the A, endogenously produced in the B, obtained via diet via C, results in D and is used for E

Answer 16

• Muscle (95% of body store)
• Endogenous production liver
• Diet (meat; supplements!)
• Weight gain (osmotic effect-> water)
• HI exercise -> Muscle mass/function

Question 17

Middle-distance athlete: 800-1500 m.
The average intensity of exercise (%VO2max) for an elite middle-distance runner during a 1500 m race will be about:

..% VO2max

Answer 17

120% VO2max

think because you use about 20% anaerobic capacity, and 100% of your aerobic (=VO2 max) capacity, thus the average intensity of exercise %VO2 max = 120%

Question 18

The net production of ATP by substrate-level phosphorylation in glycolysis is
X from blood glucose and X from glycogen

Answer 18

2, 3

 Anaerobic glycolysis: From gl-1-p to pyruvate. Pyruvate can have two starting points: 1) blood glucose, 2) skeletal muscle glycogen
Initial steps require some ATP: blood glucose -> gl-6-p, fr-6-p to fr-1,6-diP.
Glycogen breakdown does not require this first ATP.
Therefore, starting point glycogen = 1 ATP required, starting point blood glucose = 2 ATP required.
Two pyruvic acids are created, which each yield two ATPs. = 4 ATP. However, 4-2 = 2 from blood glucose, 4-1 = 3 from glycogen.

Question 19

 To keep glycolysis running, you need A
 B is returned into C with D: necessary for glycolysis
 Pay a prize: accumulation of E)

Answer 19

A) NAD+
B) NADH
C) NAD+
D) lactic acid
E) protons and acidification

Question 20

Why can long exercise not be above your max VO2 capacity?

Answer 20

Long exercise cannot be above your max VO2 capacity, as you barely use anaerobic respiration during that type of exercise.

Question 21

What are two very important enzymes in glycolysis?

Answer 21

Glycogen phosphorylase
PFK: phosphofructokinase

Question 22

What does PFK: phosphofructokinase do?

Answer 22

Activates glycolysis when cell needs energy.

• rate-limiting step
• plenty of energy? PFK is inhibiting glycolysis

Question 23

What does Glycogen phosphorylase do? And how does it get activated?

Answer 23

it breaks down glycogen to gl-1-ph
 Adrenalin + ca2+ activate glycogen phosphorylase

Question 24

What inhibits PFK?

Answer 24

ATP, citrate, lactate (H+), acyl-CoA

Question 25

How long does recovery take of..
1 Recovery ATP, PCr

2 Removal lactate, restore pH

3 Recovery muscle glycogen

Answer 25

1 Occurs within a few minutes
2 Takes much longer (liver, hearth, restoration HCO3-)
3 Takes at least 24 h, even after short races

Question 26

What is the ‘acid bath’ in a fatigue-extended sprint? What happens next? What are dietary consequences?

Answer 26

1
- Max muscle lactate after 3-7 min exhaustive exercise
- Muscle pH drops 7 to 6.3

2
- Buffer systems ‘mop up’ protons
> muscle limited capacity (carniosine)
> blood (bicarbonate)
3
- Dietary consequences: try to increase the buffering capacity for protons

Question 27

Protons inhibit PFK, and they limit X

Answer 27

muscle contraction

Question 28

How can lactate threshold be measured with breathing rate?

Answer 28

protons accumulate, bicarbonate system starts to buffer, CO2 produced: increased breathing rate.

Question 29

Muscle and liver glycogen stores in a well-nourished athlete would be sufficient to sustain approximately how many minutes of submaximal exercise (if this were the only energy source used)? The exercise is club level marathon pace.

Answer 29

60-90 min. Muscle glycogen can only be used locally.

Question 30

An elite marathon runner resynthesizes more kg of ATP than his Body Mass during a Marathon: true/false

Answer 30

True

Question 31

Max oxygen consumption: determined by two factors, namely..

Answer 31

1. Q = cardiac output = limiting capacity
2. (a-v)O2: A-V difference, or: arteriovenous oxygen difference. Oxygen extraction at level of the muscle.

Question 32

Why is there a difference in VO2 max in men and women?

Answer 32

bc of difference in lean mass.
VO2 max also differs among sports.

Question 33

Max oxygen consumption: ml/kg/min 30-40 in sedentary people, 80-90 in elite athletes

Answer 33

okay