Week 9 - Effects of aerobic and anaerobic training

Question 1

What are the two key factors to consider when training/performing?

Answer 1

source of energy (ATP-PC system, anaerobic glycolysis, aerobic metabolism) and fibres used for force production (type I, IIa, IIx)

Question 2

Describe the “Overload” principle of training.

Answer 2

Training effect occurs when a physiological system is exercised at a level beyond which it is normally accustomed

Question 3

Describe the “Specificity” principles of training.

Answer 3

Training effect is specific to:
* Muscle fibers recruited during exercise.
* Energy system involved (aerobic versus anaerobic).
* Velocity of contraction.
* Type of contraction (eccentric, concentric, isometric).

Question 4

Describe the “Reversibility” principle of training.

Answer 4

Gains are lost when training ceases.

Question 5

What are the 3 key principles of training?

Answer 5

1) Overload
2) Specificity
3) Reversibility

Question 6

What is the main goal of endurance training? What would this training look like?

Answer 6

to increase VO2max
- Large muscles groups trained with dynamic activity.
- 20-60mins, 3x per week, >50% V02max.

Question 7

What is the average increase in V02max with endurance training? How does this differ with variations in initial V02max?

Answer 7

15-20%

• Smaller increased in individual with high initial V02max. (2-3% - they may require higher exercise training intensities to obtain improvements - >70% V02max)
• Up to 50% in those with low initial V02max.

Question 8

How much of our V02max is determined by heritability (genetics) in sedentary adults?

Answer 8

50% of V02max in sedentary adults

Question 9

As well as V02max, what does genetics also play a key role in?

Answer 9

determining the training response - large variations in training adaptations reveal that heritability of training adaptations is approximately 47%.

Question 10

What is v02max defined by?

Answer 10

Fick equation

V02max = maximal cardiac output X a-vO2 difference

Question 11

What are differences in VO2max between individuals primarily due to?

Answer 11

differences in SV max - this then influences maximal cardiac output and VO2max

Question 12

In terms of short duration training (approx. 4 months) what is the dominant factor for exercise-induced improvements in V02max?

Answer 12

increase in SV dominant factor in increasing V02max

Question 13

In terms of longer duration training (approx. 28 months) what is the dominant factor for exercise-induced improvements in V02max?

Answer 13

Both SV and a-vO2 increase to improve VO2max

Question 14

How does training increase maximal stroke volume?

Answer 14

Increase preload (End Diastolic Volume)
- Increase plasma volume (days)
- Increase venous return (days)
- Increase ventricular volume (months to years)

Decreased total peripheral resistance (“afterload”)
- Decrease arterial constriction (decrease SNA)
- Increased maximal muscle blood flow with no change in mean arterial pressure

Increased contractility
- Greater force produced with each contraction

Question 15

Eccentric hypertrophy

Answer 15

chamber size and wall thickness increases in the heart

Question 16

What happens to cardiac output after training?

Answer 16

Cardiac output can be achieved with fewer beats per min. This is because HR is lower due to an increase in stroke volume.

Question 17

What does lower resting HR after training lead to?

Answer 17

• Vagal tone increased
• Also allow greater filling time (EDV)

Question 18

Why may maximum HR fall slightly in the highly endurance trained?

Answer 18

Intrinsic firing rate of SA node decreased?

Question 19

Following endurance training what happens to post-exercise HR recovery?

Answer 19

its faster

Question 20

What are the factors responsible for the training-induced increased in arteriovenous O2 difference?

Answer 20

1. Muscle blood flow increase
   - Decreased SNS vasoconstriction
   - Increased diameter and compliance of arteries
2. Improved ability of muscle fibers to extract and utilize O2 from the blood.
   - Increased capillary density: slower blood flow through muscle.
   - Increased mitochondrial number/volume.

Question 21

How does exercise training increase total capacity of vascular bed in the muscle?

Answer 21

i. large conduit artery expansion
ii. increased numbers of resistance vessels

Question 22

What happens to the transit time of RBCs as a result of training?

Answer 22

• Transit time is increased
  overall because with bigger
  capillary network, RBCs take
  longer to pass through

Question 23

Endurance training increases the volume of both … and … (80% of total) mitochondria in muscle fibers. What does this result in?

Answer 23

Subsarcolemmal and intermyofibrillar.

This results in improved oxidative capacity and ability to utilize fat as fuel.

Question 24

During submaximal exercise, explain what happens to blood flow in trained muscles?

Answer 24

Blood flow in trained muscles is LOWER because the A-V difference is greater (better oxygen extraction)

Question 25

During maximal exercise, explain what happens to blood flow in trained muscles?

Answer 25

blood flow in trained muscle is higher and the A-V difference is greater.

Question 26

What does training-induced improvements in homeostatic processes result in?

Answer 26

• A more rapid transition from rest to steady state
• A reduced reliance on limited liver and muscle glycogen stores
• Numerous CV and thermoregulatory adaptations that assist in maintaining homeostasis.

Question 27

What are the 5 adaptations in muscle fibers in response to endurance exercise training that assists the maintenance of homeostasis?

Answer 27

1. Shift in muscle fiber type (fast-to-slow) and increased number of capillaries.
2. Increased mitochondrial volume and mitochondrial turnover in skeletal muscle
3. Training-induced changes in fuel utilization.
4. Increased antioxidant capacity.
5. Improved acid-base regulation.

Question 28

Explain how endurance training promotes a fast-to-slow shift in muscle fiber muscle type.

Answer 28

Reduction in fast fibers and increase in number of slow fibers.

Incr. in slow myosin isoform, which have lower myosin ATPase activity but better efficiency (i.e. perform more work with less ATP utilization).

Question 29

What is the magnitude of fiber type change determined by?

Answer 29

Duration of training
Type of training
Genetics

Question 30

What is the effect of an increased number of capillaries surrounding muscle fibers?

Answer 30

• Enhanced diffusion of oxygen.
• Improved removal of wastes.

Question 31

Mitophagy

Answer 31

breakdown of damaged mitochondria

Question 32

What is the significance of an increased mitochondrial volume and turnover in the muscle in response to endurance training?

Answer 32

Greater capacity for oxidative phosphorylation.

Decreases cytosolic [ADP] due to increased ADP transporters in mitochondrial membrane, which results in:
* Faster ADP uptake into mitochondria and lower cytosolic ADP
* Less lactate and H+
formation.
* Less PC depletion.

However, during submaximal exercise, the steady-state VO2
is not influenced by endurance training… (i.e. volume of work is the same, just more efficient)

Question 33

What are the endurance training-induced changes in fuel utilization?

Answer 33

1) Increased utilization of fat and sparing of plasma glucose and muscle glycogen.
2) Improve plasma FFA transport and oxidation

Question 34

What are the 3 ways that endurance training adaptations improve plasma FFA transport and oxidation?

Answer 34

1) Increased transport of FFA into the muscle (i.e. from plasma): due to increase capillary density and fatty acid binding protein.

2) Transport of FFA from the cytoplasm to the mitochondria.
* Higher levels of carnitine palmitoyl transferase and Fatty Acid Translocase.

3) Mitochondrial oxidation of FFA.
* Increased enzymes of β-oxidation.
* Increased rate of acetyl-CoA formation.
* High citrate level (as result of incr. β-oxidation) inhibits PFK and glycolysis.

Question 35

How does endurance training improve the antioxidant capacity of muscle?

Answer 35

Training increased endogenous antioxidant enzymes which:
- Improves the fibers ability to remove radicals.
- Protects against exercise-induced oxidative damage and muscle fatigue.

Question 36

How does endurance exercise training improve acid-base balance during exercise?

Answer 36

Increased mitochondrial number.
* Less carbohydrate utilization + more FFA oxidation = less pyruvate formed.

Increased mitochondrial uptake of pyruvate and NADH
* Less NADH available for lactic acid formation.

Increased H4 form of LDH: decreases lactate formation

Question 37

Describe the molecular bases of exercise training adaptation.

Answer 37

Muscle contraction activates primary and secondary messengers.
Results in expression of genes and synthesis of new proteins.

Question 38

Examples of primary signals involved in exercise-induced apaptations.

Answer 38

Mechanical stretch
Calcium
AMP/ATP increased
Free radicals

Question 39

Describe the most important secondary messenger in skeletal muscle.

Answer 39

PGC-1a
- Master regulator of mitochondrial biogenesis; increased capillarization (angiongesis), and synthesis of antioxidant enzymes
- Activated by AMPK and CaMK

Question 40

What are training-induced reductions in HR and ventilation due to?

Answer 40

Improved muscle homeostasis during exercise and reduced “feedback” from muscle chemoreceptors to
cardiovascular control center.

Reduced number of motor units recruited.

Question 41

Endurance training INCREASES OR REDUCES central command outflow during submaximal exercise. What does this result in?

Answer 41

Reduces

Results in a lower HR and ventilatory response during exercise.

e.g. improvements in muscle fiber oxidative capacity means that fewer motor units are required for submaximal work.

Question 42

What is the effect of detraining?

Answer 42

Rapid decrease in VO2max.
* ↓ approximately 8% within 12 days; ↓ 20% after 84 days.

↓ SV max.
* ↓ Rapid loss of plasma volume.

↓ Maximal a-v O2 difference.
* ↓ ↓ Mitochondria.
* ↓ ↓ Oxidative capacity of muscle.
* ↓ ↓ Type 2a fibers and ↑ type 2x fibers.

Question 43

What is the initial decrease in V02max due to? What about later decreases?

Answer 43

Initial decrease = decreased SV max
Later decrease = decreased A-V O2max

Question 44

How many weeks of endurance training does it take for muscle mitochondrial volume to double?

Answer 44

5 weeks

Question 45

How quickly are mitochondrial adaptations lost with detraining?

Answer 45

• Loss of 50% of training gains within 1 week of detraining.
• Majority of adaptation lost in two weeks.

Question 46

How many weeks does it take of retraining to regain mitochondrial adaptations?

Answer 46

3-4 weeks of retraining

Question 47

How does anaerobic training increase performance?

Answer 47

• 4-10 weeks of sprint training can increase peak anaerobic power by 3-28% across individuals.
• Improves muscle buffering capacity by increasing both intracellular buffers and
  hydrogen ion transporters.
• Hypertrophy of type 2 muscle fibers and elevates enzymes involved in both the ATP-PC system and glycolysis.
• High intensity interval training >30 seconds (at near or above VO2 max) promotes mitochondrial
  biogenesis

Question 48

During the first 4 months of an endurance exercise training program, the initial increase in V02max is primarily due to what?

Answer 48

increases in SV and increases in maximal cardiac output

Question 49

Endurance training has been shown to reduce the oxygen deficit in subjects performing a bout of submaximal exercise. What is this likely due to?

Answer 49

increases in the number of mitochondria and capillaries