Energy metabolism 1 Flashcards
For very high force concentrations lasting 1-2 s, the initial energy source is from…
ATP
(compared to glycolysis, creatine phosphorylation, phosphocreatine stores)
When are phosphocreatine stores broken down?
when talking about exercise of 2-20 seconds.
After what period of time does maximal dynamic exercise become predominantly aerobic?
2 min (>800 m) , >60% aerobic
Phosphocreatine + anaerobic glycolysis =
Oxidative metabolism =
..phosphorylation
- substrate-level
- oxidative
Which fiber types exist in humans? characteristics?
> T1: slow-twitch (red: aerobic: fatigue-resistant)
T2: fast-twitch (white: fast, lots of force, easily fatigued)
T2X: fastest, T2A: less fast
Which fiber types are used when weight lifting? (using maximal force)
All
Why are some fibers red and some white?
White vs red appearance depends on capillarization. Mito density is also higher in red fibres vs white.
Weight lifting performance is not determined by a limiting energy availability, because..
Weight lifting requires activation of all muscle types at same moment, which requires technique, skills, coordination. Performance not determined by a limiting energy availability.
A sprinter uses the…. metabolism
anaerobic metabolism (= phosphagen (ATP + Pcr) and glycolytic)
Resynthesis of PCr requires
energy (ATP).
: The complete resynthesis of PCr after very high intensity exercise normally takes (time):
about 4 minutes (relatively short time)
Phosphocreatine resynthesis during recovery from exercise is inhibited by:
a) an excess of creatine
b) hyperventilation
c) an excess of oxygen
–> a lack of oxygen
e) submaximal muscle contractions
Glycolytic system:
Glycogen will be broken down with A
-> B
glycogenolysis
-> glycolysis
Glycolytic system:
Reach max not until after 5 s
Maintained up to 30 sec
Rate lower (2x), size higher (4x) compared to Pcr: power output lower
Fatigue in exercise <10s:
Max power reached after X
Performance depends on X achieved early in exercise:
- A
- B
X implicated
A, B, C
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
Creatine is stored in the A, endogenously produced in the B, obtained via diet via C, results in D and is used for E
- Muscle (95% of body store)
- Endogenous production liver
- Diet (meat; supplements!)
- Weight gain (osmotic effect-> water)
- HI exercise -> Muscle mass/function
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
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%
The net production of ATP by substrate-level phosphorylation in glycolysis is
X from blood glucose and X from glycogen
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.
To keep glycolysis running, you need A
B is returned into C with D: necessary for glycolysis
Pay a prize: accumulation of E)
A) NAD+
B) NADH
C) NAD+
D) lactic acid
E) protons and acidification
Why can long exercise not be above your max VO2 capacity?
Long exercise cannot be above your max VO2 capacity, as you barely use anaerobic respiration during that type of exercise.
What are two very important enzymes in glycolysis?
Glycogen phosphorylase
PFK: phosphofructokinase
What does PFK: phosphofructokinase do?
Activates glycolysis when cell needs energy.
- rate-limiting step
- plenty of energy? PFK is inhibiting glycolysis
What does Glycogen phosphorylase do? And how does it get activated?
it breaks down glycogen to gl-1-ph
Adrenalin + ca2+ activate glycogen phosphorylase
What inhibits PFK?
ATP, citrate, lactate (H+), acyl-CoA
How long does recovery take of..
1 Recovery ATP, PCr
2 Removal lactate, restore pH
3 Recovery muscle glycogen
1 Occurs within a few minutes
2 Takes much longer (liver, hearth, restoration HCO3-)
3 Takes at least 24 h, even after short races
What is the ‘acid bath’ in a fatigue-extended sprint? What happens next? What are dietary consequences?
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
Protons inhibit PFK, and they limit X
muscle contraction
How can lactate threshold be measured with breathing rate?
protons accumulate, bicarbonate system starts to buffer, CO2 produced: increased breathing rate.
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.
60-90 min. Muscle glycogen can only be used locally.
An elite marathon runner resynthesizes more kg of ATP than his Body Mass during a Marathon: true/false
True
Max oxygen consumption: determined by two factors, namely..
- Q = cardiac output = limiting capacity
- (a-v)O2: A-V difference, or: arteriovenous oxygen difference. Oxygen extraction at level of the muscle.
Why is there a difference in VO2 max in men and women?
bc of difference in lean mass.
VO2 max also differs among sports.
Max oxygen consumption: ml/kg/min 30-40 in sedentary people, 80-90 in elite athletes
okay
