Aerobic Adaptations

Question 1

What are the acute responses to aerobic exercise

Answer 1

• Ventilation: Increases due to neural input from central / peripheral receptors
• HR: Increases due to reduced PNS influence and increased sympathetic drive / hormonal effects
• SV: Increases due increased SNS drive (increased contractility) and EDV
• BP: SBP increases due to increase in Q and DBP remains unchanged / decrease slightly (vasodilation)
• Redistribution of BF: Away from inactive organs to working skeletal muscles and heart
• Oxygen Consumption: O2 deficit is the difference between O requirement and O utilisation at commencement of exercise

Question 2

What does aerobic training improve

Answer 2

• Improves the ability to sustain a particular level of physical effort
• Occurs via improvements in functional capacities related to oxygen transport and utilisation
• Fick Equation: VO2 = Q x a-vO2 difference
• Central adaptations increase Q
• Peripheral adaptations increase a-vO2 difference

Question 3

What are central adaptations

Answer 3

• HR: Reduced at rest / sub-maximal exercise, training increases vagal tone (PSNS), lower cardiac O2 cost, greater filling time
• SV: Increases due to increased left ventricular volume / mass (increased EDV / preload), increased ejection fraction increases contractility
• Plasma Volume: Increase of ~10-20%, increased EDV, SV, temperature regulation, Hb
• BF: Distribution of blood to more oxidative muscle fibres, reduced splanchnic and renal, increase in skeletal muscle BF (increase in Q and vasodilation)

Question 4

What are peripheral adaptations

Answer 4

• Mitochondria: Increase size / number, increased oxidative enzymes (citrate synthase) due to tissue hypoxia
• Capillaries: Increased density due to increased stress (pressure), increased O2 delivery / transit time
• Fibre Type: Type IIx to type IIa to type I
• Myoglobin: Possibly small increase in intramuscular myoglobin content
• Lactate: Decreased
• Enzymes: Changes in LDH and PDH

Question 5

What is the magnitude of response to aerobic training

Answer 5

Determined by:

• Genetics
• Age
• Previous training status (VO2 max)
• Training load (training intensity x volume)

Question 6

What determines aerobic performance

Answer 6

• VO2 max, critical power and economy, thresholds occur at a higher work rate
• VO2 max: Highest rate that oxygen can be taken up and used by the body during exercise, result of central and peripheral adaptations

Question 7

What is the anaerobic threshold and how to improve it

Answer 7

• Power speed / pace / power at “threshold” is perhaps the most important determinant of endurance performance
• Closely linked to critical power, ventilatory / lactate threshold, MLSS (maximum lactate steady state)
• Change occurs through peripheral adaptations
• 40-60% of VO2 max (untrained)
• 80-90% of VO2 max (marathon / distance swimmers)
• 60-85% of VO2 max (sprinters)

Question 8

What is critical power

Answer 8

• Maximum intensity at which work can be sustained indefinitely without drawing on W’
• Practically / realistically 60mins

Question 9

What is the ventilatory threshold

Answer 9

• Intensity of exercise where a non-linear increase in VE is observed, increase in H and CO2, dramatic increase in air expired per minute

Question 10

What is the lactate threshold

Answer 10

• Intensity of exercise where lactate begins to accumulate in the blood
• Lactate production outstrips utilisation, associated with increased H
• Inhibits PFK and reduces rate that glycolysis occurs at

Question 11

What are aerobic training alterations to fuel metabolism

Answer 11

• Increased utilisation of fat metabolism and decreased utilisation of CHO metabolism
• Decreased plasma FFA
• Increased intra-muscular triglyceride (changes source of FFA)
• Improve B oxidation pathway

Question 12

What is EPOC

Answer 12

• Excess post exercise oxygen consumption
• Increased oxygen consumption due to increased metabolic demand post exercise
• Increased HR / ventilation, replenishing Mb stores, increased body temp, anabolic processes

Question 13

Provide an overview of central and peripheral adaptations

Answer 13

• Central: Reduced HR at rest and during exercise, increased SV, increased plasma volume and increased blood flow to skeletal muscles
• Peripheral: Increased mitochondria, increased capillary density, increased oxidative capacity of muscle fibres, increased myoglobin content