Applied Exercise Physiology

Question 1

Define exercise intensity

Answer 1

Rate of metabolic energy demand

Question 2

Describe the 4 ways exercise intensity is measured

Answer 2

• Cardiovascular - heart rate
• Respiratory - oxygen consumption and CO2 production
• Metabolic - lactate, hydrogen, ATP and phosphocreatine
• Other - external load (power output, speed), rating of perceived output (RPE)

Question 3

Describe exercise intensity prescription

Answer 3

• Aims to control/equalise the intensity/effort of exercise across individuals
• Can be expressed in absolute (eg running at 13km/h) or relative (eg running and 60% max speed) terms

Question 4

What are issues with traditional methods of exercise intensity prescription? eg %HRmax

Answer 4

• Assumes that physiological response is stable over time (eg will stay at 60% HRmax)
• Assumes there will be similar physiological responses between individuals working at the same relative intensity

Question 5

Describe metabolic thresholds

Answer 5

• Points at which physiological variables change in response to exercise
• Represent disturbances to homeostasis/energy demand
• Commonly used thresholds are lactate, gas exchange and ventilatory thresholds

Question 6

How are metabolic thresholds better than traditional methods?

Answer 6

• Consider the intensity profile of an individual
• Boundaries that separate the exercise intensity domains
• Individualised

Question 7

Describe the process of why lactate thresholds are used

Answer 7

• Process of glucose –> pyruvate –> lactate (glycolysis)
• Increased energy demands = greater rate of glycolysis –> greater production of lactate
• Marker of physiological stress

Question 8

How are lactate thresholds measured?

Answer 8

• Series of exercise steps lasting 3-5 minutes
• Brief rest between each step before intensity is increased
• Important to start at a low intensity to provide a stable baseline

Question 9

Outline the different lactate thresholds

Answer 9

• LT1 - first noticeable rise in lactate above baseline, the initial challenge to homeostasis with an increased metabolic rate (paticularly glycolysis)
• LT2 - Accelerated accumulation of blood lactate, disproportionately increased metabolic rate (pat. glycolysis)

Question 10

What are the methods of determination for the lactate thresholds?

Answer 10

• Visual inspection
• Curve fitting
• Using fixed values

Question 11

Describe the Flick Principle

Answer 11

• Oxygen consumption (VO2) determined by cardiac output and the difference between arterial and venous oxygen content at the capillary (avO2 diff)
• VO2 = cardiac output x avO2 diff

Question 12

What are the limiting factors of oxygen uptake?

Answer 12

• Pulmonary (O2 saturation) - saturation of arterial blood with oxygen
• Cardiac (O2 delivery) - cardiac output - stroke volume
• Skeletal muscle (O2 extraction) - extraction/diffusion of oxygen into mitochondria
• O2 carrying capacity - amount of RBC’s/Hb