lecture 18

Question 1

How does endurance training affect mitochondrial density?

Answer 1

↑ Mitochondrial density
↑ Aerobic capacity
↑ Fat oxidation
↑ Endurance performance

up in enzymes

Question 2

What is the effect of progressive training on mitochondrial content?

Answer 2

Progressive overload → ↑ mitochondrial content
Requires increasing workload over time
Prevents training plateau

Question 3

How does endurance training (8–10 weeks, 20–40 min, 4d/week, progressive load) affect mitochondrial content in muscle?

Answer 3

Increases mitochondrial volume density in muscle
↑ content of ETC enzymes:
SDH = Complex II
Cytochrome c oxidase = Complex IV
More mitochondrial proteins → improved oxidative ATP production
Leads to better aerobic energy production and endurance

Question 4

skeletal muscles adapt to endurance training

mitochondria

substright utilization at the same absolute workloadççç

lactate production

Answer 4

volumne density uo=p
up mitochondrial numbers
up oxidative enzymes

reduce carb using more carb at same poweroutput

lactate production
reduce
improve lactae threshold

Question 5

What happens to RER at the same absolute workload after 6 weeks of HIIT training?

Answer 5

RER decreases
Increased fat oxidation at same workload
Reduced carbohydrate reliance
Indicates improved metabolic efficiency and mitochondrial adaptation

Question 6

Why does fuel use change after training?

Answer 6

A decrease in [ADP], [AMP], and [epinephrine]
↓ activation of PHOS and PFK enzymes (reduced activation of glycogenolysis & glycolysis)
Muscle glycogen is spared
Glucose oxidized decreases
Lactate production reduces
Increased lipid oxidation
Increased lipid delivery to muscle
Increased concentration of enzymes for lipid oxidation

Question 7

What is the time course of mitochondrial adaptations during training and detraining?

Answer 7

1 week detraining → ~50% loss of mitochondrial gains
~5 weeks detraining → full loss of adaptation
4 weeks retraining → regain loss from first week detraining
Shows mitochondrial content is highly reversible and rapidly responsive to training status

Question 8

What happens to mitochondrial content and VO₂max during 6 weeks of detraining?

Answer 8

Mitochondria are highly sensitive to detraining and decline quickly, but VO₂max decreases more slowly because it depends on multiple physiological systems.

Question 9

What is the effect of a single HIIT session on glucose regulation in T2D?

Answer 9

Lowers blood glucose post-exercise
Increases GLUT4 translocation to muscle membrane
Enhances glucose uptake into muscle
Repeated sessions → cumulative improvements in insulin sensitivity and glucose control