Aerobic Fitness & Training Adaptations

• Lungs show no adaptations themselves

  • Only fatigue resistance with intense training (in respiratory muscles)
  • Less VE in submax, but this not due to lung adaptations
  • More from ability to utilise
  • Ventilation & Control
• Increase Cardiac Output (Qc) max by increase SV and increase HR range:

  • Decrease HR (at rest & submax exercise)
  • Increase filling time & HRR
  • Doesn’t have to work as hard & use as much O2 & energy
  • Also less cardiac O2 demand & energy requirement
  • Increase ventricular volume, compliance & contractility
• VO2 max increase only ~5 - 30% BUT endurance can increase >300%

  • VO2 max seems ultimately limited by O2 delivery:
  • Factors influencing O2 delivery increase <50% (eg left ventricle volume, RBCs)
  • Submax endurance seems limited more by muscle factors
  • These can increase 200+% (eg mitochondrial volume)
• O2 delivery & muscle adaptations key aerobic adaptations
• Training effects include increase in:

  • Increase BV (PV & RCV)
  • Increased capillarisation, vascular capacity
  • Fibre type shifts & oxidative fibre size increase
  • Increase mitochondria volume, more enzymes of aerobic metabolism, ETC, etc These allow greater fat utilisation as higher intensities, sparing glycogen
  • Can get similar response to varying regimens, intensive & prolonged
  • Numerous signalling molecules involved, eg to turn on transcription of genes for mitochondrial proteins (number of different stimuli for adaptations)