Aerobic Fitness and Performance (year 2) Flashcards
What is Aerobic Fitness?
• The capacity to sustain a given speed or work rate
for the longest possible time
• For exercise longer than 120s, the majority of
energy is derived through oxidative metabolism
• Requires O2
to be delivered to the mitochondria,
sufficient availability of fuels and appropriate
oxidative capacity within the mitochondria
What are the Parameters of Aerobic Fitness?
- Maximal Oxygen Uptake
- Maximum rate that the body can consume oxygen
- Running Economy
- How much oxygen it costs to run a certain speed
- The fractional utilization of maximal oxygen uptake
- Linked to the lactate accumulation in muscles and blood
- Oxygen Uptake kinetics
- The rate at which oxygen uptake rises when we start exercising
what is Maximal Oxygen Uptake?
- Integrated capacity of pulmonary, cardiovascular and muscular systems
- Highest O2 uptake despite further increases in work rate/exercise intensity
- Reflects uptake, transport and utilisation of O2
- Criterion measure of:
- Intervention efficacy
- Environmental impact
- Disease prognosis
Verifying a VO2 Max
• Leveling off in VO2 despite increasing work rate: <150 ml∙min–1 or <2.1 ml∙kg–1
∙min–1
• Secondary criteria:
• Post-exercise blood lactate >8 mmol∙L
–1
• R >1.15
• HR within 10 beats∙min–1 of age-predicted maximal HR
• RPE ≥ 18
• Should not expect participants to meet all criteria
what are the determinants of VO2 Max?
Oxygen Utilisation–>Peak VO2=cardiac output (Q)(O2 Delivery)x aterio-venous O2 difference(O2 Extraction)
Effects of Training on VO2 Max?
• 15-30% increase in VO2max with endurance training in adults
- Effect of resistance training less clear
- 3/17 studies in young adults show positive effect
- 6/9 in older adults in older adults show positive effect
• Effect of HIIT equal to, or greater than, endurance
training
VO2 Max and Performance: Limited practical applicability?
- Can’t distinguish between performances – limited adaptability in elite athletes
- Can’t design optimal training programmes
what is Lactate threshold:
- The point at which blood lactate concentration first begins to increase systematically and consistently
- Some labs use a blood lactate concentration of 2mmol·l-1 but direct identification of first breakpoint in lactate curve preferable
- Mechanisms of fatigue may differ above and below the lactate threshold
Lactate Threshold and Performance:
• Typically 50-60% VO2max in healthy, untrained people, increased to ≥80% in trained people
• Higher relative exercise intensity can be sustained without the accumulation of blood lactate =
delayed onset of fatigue
- Strong predictor of endurance performance
- Applicable to design/optimisation of training
• Optimal intensity for improvements
in endurance fitness
what are Oxygen Uptake Kinetics?
The rate at which oxygen uptake changes in response to a change in metabolic demand
• Requires coordination between the respiratory, cardiovascular and muscular systems
• Pulmonary VO2
reflects muscular VO2 to within ±10%
• The faster these kinetics, the less reliance on finite non-oxidative resources
- The faster these kinetics, the lower the oxygen deficit
- Response is dependent on exercise intensity
Effect of Training on VO2 Kinetics?
- Highly sensitive to endurance training and HIIT
- Speeds the phase II time constant
- Decreases the slow component amplitude
Potential Mechanisms for improved VO2 kinetics: Metabolism?
Central: Metabolism
More rapid increase in O2 extraction (Oxidative capacity, Muscle fibre type, Peripheral: muscular)
Speeded Phase 2
Potential Mechanisms for improved VO2 kinetics: Nervous system?
central: Nervous system, faster response to altered state:
Enhanced bulk O2 delivery (Central : cardiovascular)
Speeded Phase 2
what is Exercise Economy?
• Oxygen cost of a given exercise intensity or speed
• High VO2max is important, but cannot discriminate
performance capability in athletes with similarly high values
- Exercise economy may explain the difference
- Good economy can compensate for relatively low VO2 max values in elite athletes
Aerobic performance is comprised of 3 things?
Aerobic contribution,
rate of aerobic energy expenditure,
Exercise economy
all of the 3 are interrelated