The Physiology of Training: Effects of aerobic and anaerobic training

Question 1

What are 2 key things to consider when training/performing?

Answer 1

• Source of energy (contribution of each energy system)
• Fibres used for force production (muscle fibre recruitment)

Question 2

Principles of training - what is overload?

Answer 2

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

Question 3

Principles of training - what is specificity?

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

Principles of training - what is reversibility?

Answer 4

Gains are lost when training ceases.

Question 5

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

Answer 5

Training to increase VO2 max (large muscle groups, dynamic activity)

20 to 60 min, ≥3 times per week, ≥50% VO2 max.

Question 6

What is the average % increase in VO2 max for people who do endurance training, and how does this differ between trained and untrained athletes?

Answer 6

Average = 15 to 20% increase.
*Smaller increases in individuals with high initial VO2 max.
* Individuals with high VO2 max may require higher exercise training intensities (>70% VO2 max) to obtain
improvements.
*Up to 50% in those with low initial VO2 max, 2-3% improvements in low responders.

Question 7

How much does genetics determine VO2 max?

Answer 7

Approximately 50% of VO2 max in sedentary adults.
- Genetics also plays a key role in determining training response.

Question 8

What is the average improvement in VO2 max, and the difference in improvement between high-low responders?

Answer 8

Average improvement in VO2 max - 15-20%
* Low responders improve VO2 max by 2 to 3%.
* High responders can improve VO2 max by ~50% with rigorous training.

Question 9

VO2 max is defined by the Fick equation. What is this equation?

Answer 9

VO2 max = maximal cardiac output x a-vO2 difference.

Question 10

What are the differences in VO2 max between individuals determined by?

Answer 10

Primarily due to differences in SV max.
* Maximal cardiac output and VO2max are tightly coupled

Question 11

How does short-duration training improve VO2 max (4 months)?

Answer 11

Increase in SV dominant factor in increasing VO2 max.

Question 12

How does longer-duration training improve VO2 max (28 months)?

Answer 12

Both SV and a-vO2 increase to improve VO2 max.

Question 13

Endurance Training Increases Stroke Volume in Several Ways, one of these being increased preload, how?

Answer 13

-↑ Preload (EDV).
- ↑ Plasma volume. (days)
- ↑ Venous return. (days)
- ↑ Ventricular volume (months to years)

Question 14

What occurs with eccentric cardiac hypertrophy?

Answer 14

Chamber size and wall thickness increased

Question 15

Endurance Training Increases Stroke Volume in Several Ways - what are these?

Answer 15

• Decreased afterload (TPR)
• Increased contractility
• Increased preload (EDV)

Question 16

How does decreased afterload increase SV?

Answer 16

• ↓ Arterial constriction (↓SNA).
• ↑ Maximal muscle blood flow with no change in mean arterial pressure.
• i.e. increase in CO parallels the decrease in resistance.

Question 17

How does increased contractility increase SV?

Answer 17

*↑ Contractility (independent of SNS input and other factors constant (EDV, HR, afterload))
* Greater force produced with each contraction (animal studies)
* Improved ‘twist mechanics’ of the LV.

Question 18

What is the relationship between CO and O2 consumption?

Answer 18

Predominantly linear.

Sub-max reduction in CO in highly trained…

Question 19

At any given sub-maximal workload heart rate is lower following training due to an increase in stroke volume. Therefore, the required cardiac output can be achieved with fewer beats per min. Why is resting heart rate lower after training?

Answer 19

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

Question 20

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

Answer 20

Intrinsic firing rate of SA node decreased?

Reduced metabolic cost for cardiac muscle and longer diastolic time for coronary blood flow

Question 21

How does muscle blood flow increase?

Answer 21

-↓ SNS vasoconstriction
-↑ diameter and compliance of arteries

• Increased arterial diameter is SPECIFIC TO LIMB BEING USED
• Permits greater ‘volume flow per beat’ to limb

Question 22

How does the muscle fibres improve the ability to extract and utilize O2 from the blood?

Answer 22

*↑ Capillary density.
* Slower blood flow through muscle.
*↑ Mitochondrial number/volume

Question 23

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

Answer 23

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

Question 24

Increased capillary supply and O2 delivery in trained muscle

Answer 24

-During contractions, transit
time of RBCs decreases
-Training increases capillary
density, thus reducing
diffusion distance
-Transit time is increased
overall because with bigger
capillary network, RBCs take
longer to pass through

Question 25

What effect does endurance training have on mitochondria in muscle fibres?

Answer 25

Increases the volume of both subsarcolemmal and intermyofibrillar
(80% of total) mitochondria in muscle fibers.
- Results in improved oxidative capacity and ability to utilize fat as fuel

Question 26

Do muscle mitochondria adapt fast or slow to training?

Answer 26

Muscle mitochondria adapt quickly to training.
* Double within 5 weeks of training

Question 27

What difference do vascular remodelling and muscle metabolic changes make to muscle blood flow in exercise?

Answer 27

• During submaximal exercise, blood flow in trained muscles is lower BECAUSE
  the A-V difference greater (better O2 extraction)
• During maximal exercise, blood flow in trained muscles is higher AND the A-V difference is greater