Adaptations to Aerobic Training

Adaptations to Aerobic Training

• Aerobic training improves cardiorespiratory endurance, the ability to sustain prolonged dynamic exercise.
• Improvements occur through multi-system adaptations including cardiovascular, respiratory, muscle, and metabolic systems.
• Endurance training elevates maximal endurance capacity (VO2 max).
• Submaximal endurance capacity also increases, meaning a lower heart rate at the same submaximal exercise intensity.
• This is more closely linked to competitive endurance performance.
• The Fick Equation is important to remember.

Aerobic Adaptations

• VO2 max increases due to enhanced oxygen-carrying capacity (hemoglobin and myoglobin), plasma volume, capillarization, mitochondrial number and size, and mitochondrial enzymes.
• Fiber diameter decreases and heart function (Q & SV) increases.
• More oxidative fibers (Type IIa) increase.

Overload Example

• Arteries and veins run parallel to muscle fibers forming a network around them.
• Overload stimulates increased capillarization.
• Vascular stretch and shear stress from increased blood flow during exercise develop more capillaries, improving training effectiveness.
• Trained muscle has a higher capillary-to-muscle fiber ratio.
• Enhanced microcirculation improves removal of heat and metabolic byproducts from active tissues, alongside oxygen, nutrient, and hormone delivery.

Muscular Adaptations

• Myoplasticity determines the ability of muscle fibers' genetic machinery to change the quantity or quality of protein expression.
• Adaptations depend on the demands placed on the muscle.
• Transcription involves the expression of target genes in DNA to create mRNA.
• Translation utilizes ribosomes to translate mRNA, attaching amino acids to create proteins.

Cardiovascular Adaptations

• O2 transport system and Fick equation are crucial.
• VO2 max increases due to increased max SV x max HR x max (a-v)O2 difference.
• Heart size and LV volume increase with training (cardiac hypertrophy).
• Plasma volume increases with training leading to higher EDV and SV.
• SV increases due to the volume loading effect / Frank-Starling Law, and increased force of contraction with training.

Cardiovascular Adaptations (Continued)

• Resting heart rate (HR) decreases markedly with training (~1 beat/min per week). This reduced HR is due to increased parasympathetic nervous system influence and decreased sympathetic nervous system influence on the heart.
• Submaximal HR remains the same for the same absolute intensity of exercise.
• Training provides greater reductions in submaximal HR at higher submaximal intensities.
• Maximum HR does not change with training.
• Faster recovery HR also occurs and can be used to predict VO2max.

Mitochondrial Adaptations

• Mitochondrial density increases leading to increased (a-v)O2max.
• Endurance training improves the quality of muscle mitochondria through biogenesis (production of new, healthy mitochondria) and reduces the degradation of mitochondria.
• PGC-1a regulates these changes.
• Testing involves measuring PGC-1a and other mitochondrial enzymes.

Lactate Threshold

• Lactate threshold rises in response to aerobic training.
• Aerobic systems adapt to work more efficiently and produce ATP at a faster rate to handle increasing demands.
• Training allows the body to delay the accumulation of lactate at a higher workload.

Bioenergetic Adaptations

• Aerobic enzymes and oxidative potential of fast-twitch (FT) fibers increase.
• Glycogen, VO2 max, and cross-section size of slow-twitch (ST) fibers also increase with training.
• Capillaries increase in response to training leading to more efficient oxygen delivery.

This quiz focuses on the physiological adaptations resulting from aerobic training, particularly in terms of cardiorespiratory endurance and VO2 max improvements. You'll explore how various systems such as cardiovascular, respiratory, and muscular respond to endurance training. Key concepts like the Fick Equation and the role of muscle fiber types will also be examined.