Exercise Flashcards
What is a hyperinsulinemic euglycemic clamp?
Inject more insulin than normal levels, injecting glucose (clamped at app. 5 mmol/L)
What is the glucose infusion rate (GIR)?
The glucose infusion rate at which the blood glucose level is stable at app. 5 mmol/L. GIR is given in mg/min/kg
High: insulin sensitive
Low: less insulin sensitive/insulin resistant
Which are the three metabolic pathways for ATP production?
Creatin kinase, glycogenolysis/glycolysis, and oxidative phosphorylation
How is the relationship between shortening velocity and force?
Inverse
What does resistance training improve?
Both force and power
What are some adaptation with resistance training?
Increased muscle fiber size (diameter), especially type II, but also type I
How does aging affect muscle fiber size?
Reduces
What is improved with endurance training?
VO2 max
Time to exhaustion
How does the blood parameters change during endurance exercise?
Blood glucose reduction, blood lactate increation, blood FFA increation
What substrates are utilized during different intensities of endurance exercise?
High: sugar
Medium: sugar and fat
Low: fat
Describe the relationship between sugar and fat utilization during exercise.
At low intensity, sugar and fat are utilized app. equally, at high intensities sugar are the substrate primarily used for utilization.
What is the RER, and what can it be used for?
Respiratory exchange ratio, the ratio between fat:sugar utilized
At steady state, RER = RQ (respiratory quotient)
RER is what can be measured, RQ is in tissue
RER = VCO2/VO2
= 1 : CHO
= 0.7 : lipids
What does adrenalin stimulate during exercise?
Glycogeneolysis, gluceneogenesis, and lipolysis
What does glucagon stimulate during exercise?
Glycogeneolysis, gluceneogenesis, ketogenesis
Inhibits: glucogen synthesis and glycolysis
How does exercise affect the plasma substrate of glucogon, adrenalin, insulin, and GH?
Increases: glucagon, adrenalin and GH
Decreases: insulin
How are myokines believed to be involved in organ cross-talk?
IL-6 (myokine) from muscle –> lipolysis and gluconeogenesis in liver and adipose tissue
What can be limiting factors during endurance exercise?
Muscle fatigue: hypoglucemia, glycogen depletion, Ca2+ handling and K+ homeostasis
How is K+ homeostasis involved in muscle fatigue during prolonged exercise?
Na+/K+ pump cannot keep up with the production of K+
How can muscle fatigue be manipulated?
Initial muscle glucogen determines duration –> supercompensation: muscle glucogen enhanced by prior exercise and CHO intake or by prior exercise + low CHO intake followed by high CHO intake (psychologically tough)
What are improved with exercise training regarding VO2max?
Pulmonary ventilation and stroke volume => cardiac output => VO2 max
Also increase plasma volume and heart size
What is the limiting factor of VO2 max?
The pumping capacity of the heart
How is the relationship between max O2 delivery and VO2?
Linear
What are improved with exercise training regarding time to exhaustion?
Increased capillarization + increased mitochondrial capacity
(more mitochondrial enzymes lead to a bigger portion of pyruvate being utilized, which decrease the lactate formation) –> Change in substrate utilization: more fat is utilized
Give an overview of effect of endurance exercise training on VEmax, VO2max, Qmax, SVmax, heart volume, plasma volume, and submax HR
Increase everything but submax HR, which is decreased.
Give an overview of effect of endurance exercise training on capillarization, oxidative enzymes, submax blood lactate and submax RER.
Increase in capillarization and oxidative enzymes, decrease in submax blood lactate and submax RER
Desribe glycolysis/glycogenolysis.
Glucose/glycogen –> pyruvate –> 2 ATP + lactate in cytoplasm
During high intensity, short time exercise
Not a lot of ATP
Describe oxidative phosphorylation.
Electrontransport chain in mitochondria
More ATP
Longer periods of exercise
Describe creatine kinase.
PhosphoCreatin + ADP –> ATP
Fast conversion, early in exercise
Small amount
What is hypoxia?
Low ambient O2 levels
Per how many metres does the barometric pressure decrease by half?
5500 m
What are the PO2_alv and PO2_art at sea level, and how low can PO2_art be before the turning point?
PO2_alv (sea): 105 mmHg
PO2_artv (sea): 100 mmHg
Critical PO2_art: 60 mmHg
At which altitude is the PO2_art app. 60 mmHg?
> 3 km
What does hypoxia lead to?
Low ambient O2 –> reduction in max obtainable arterial O2
Low gradient between alveolar air and pulmonary capillary blood –> equilibrium may not be reached
O2 uptake might become diffusion limited
How does the body cope with acute hypoxia?
- Peripheral chemoreceptors sense low PO2 –> signals to CNS –> increased (hyper) ventilation –> increased PO2_alv
- Submax HR increase
- SV decrease a bit
- Submax CO increase
What protects the PO2_art at altitudes </= 3 km?
Characteristics of the O2-Hb dissociation curve
How does the altitude affect the ability to perform?
VO2max decrease with altitude
Saturation of O2 also decreses,
What are the effects of prolonged hypoxia (acclimatization to high altitude)?
- Increase in red blood cell production => [Hb] increase –> hematocrit value increase
- VE_alv increase
- Submax HR decrease
- DPG increase in red blood cells (glycolysis intermediate) –> reduce Hb saturation –>O2 is easilier delivered to tissue
- Increased pulmonary diffusion capacity
- May affect tissue capillarization
- Increase in oxidative enzymes
Why is the ventilation not reduced at prolonged hypoxia because of the higher pH?
Normally: VE increase –> PCO2_alv decrease –> PCO2_art decrease –> pH increase –> reduced VE
BUT: the body will decrease pH by secreting less acid in urine –> ventilation is not reduced
What makes the hematocrit increase?
EPO (erythropoietin) signaling
How is EPO expression increased during hypoxia?
By HIF1 = hypoxia inducible factor 1, which is a transcription factor
Where is EPO secreted from?
The kidney
Describe how EPO is produced.
HIF-1-alpha is degraded when O2 is availble, but not during hypoxia
HIF-1-beta is always present
HIF-1-alpha + HIF-1-beta –> HIF-1 => EPO transcription
What is the function of EPO?
Prevents apoptosis of red cblood cells (erythrocytes) (is anti-apoptotic)
What might EPO signaling in the brain contribute to?
BDNF increase. Low BDNF levels has been associated with depression
How are HIF-1-alpha regulated?
By hydroxylation
What is hyperthrophy?
Increase in diameter of muscle cell.
What are the mechanisms behind hyperthrophy?
Resistance exercise induce a net protein synthesis.
Degradation of muscle protein –> net increase in muscle protein
What are satellite cells in muscles?
“Stem cells” involved in muscle hyperethrophy and reparing muscle damage
What activates satellite cells?
IGF-1 and myogenin mRNA
What is myostatin mRNA?
A growth inhibitor
What does endurance exercise increase in transcription?
Stress responsive genes (very short half-life: 1-2 h), early responding metabolic genes (half life app. 12 h), and mitochondrial enzyme genes (app. 24 h)
How can transcription factors be regulated?
By de/phosphorylation:
- Localization
-Affinity for DNA
- Transcriptional activation
By proteolytic cleavage:
- Localization
What are transcriptional coactivators often recruiting?
HAT, which mediates loosening of chromatin structure enabling transcription
