Aerobic Training

How does cardiac output change from rest to steady-state exercise?

Increases rapidly, then gradually, then plateaus. At maximal exercise, may increase to 4× resting level.

What two factors increase stroke volume during exercise?

1) Increased EDV (end-diastolic volume)
2) Sympathetic stimulation (epinephrine) increasing contractility

How does heart rate respond to acute aerobic exercise?

Increases linearly with intensity (sympathetic anticipation via epinephrine). Explains continued increase in Q after SV plateaus.

How does systolic BP respond to acute aerobic exercise?

Substantial increases with increasing exercise intensity.

How does diastolic BP respond to acute aerobic exercise?

Stays the same or decreases (due to vasodilation).

What happens to blood flow distribution during acute aerobic exercise?

↑ Flow to active muscles (dilation of local arterioles)
↓ Flow to other organs (constriction of arterioles)

What is minute ventilation (VE)?

Volume of air breathed per minute (L/min). Increases via depth, frequency, or both.

How does breathing pattern change with exercise intensity?

Depth increases at low intensities; frequency takes on greater role at higher intensities.

How is most CO₂ transported in the blood?

Combined with H₂O and delivered to lungs as bicarbonate.

At high intensities, why does ventilation increase?

To clear CO₂, NOT to get more O₂. Corresponds with lactate threshold.

What triggers the ventilatory breakpoint?

Acidosis (from lactic acid accumulation)

What are the central (cardiac) adaptations to aerobic training?

Greater Q at max, greater SV at any intensity, greater parasympathetic tone, decreased resting/submax HR.

How does the heart structurally adapt to aerobic training?

LV chamber volume and wall thickness increase (eccentric + concentric hypertrophy).

What happens to contractility with aerobic training?

Increases – greater strength of each contraction.

Why does resting HR decrease with aerobic training?

Increased SV matches needed Q, so HR can be lower.

What are peripheral adaptations to aerobic training?

Increased capillary density (skeletal & cardiac muscle), increased mitochondrial density.

How does increased mitochondrial density improve O₂ uptake?

Decreases diffusion distance for O₂ and metabolic substrates; increases capacity for O₂; increases a-vO₂ difference.

What happens to ventilatory capacity with chronic aerobic training?

Little change – not typically limiting. ↑ VE at max, ↑ tidal volume, ↑ breathing frequency at max, ↓ rest/submax VE.

What is exercise economy?

O₂ uptake needed to perform at a specific intensity. Ratio of mechanical work to energy cost.

What factors influence exercise economy?

Fiber transition, metabolic adaptations, biomechanics, technique, anthropometrics (stride length, body weight, air resistance).

What fiber type hypertrophy occurs with aerobic training?

Type I muscle fiber hypertrophy. Type II can hypertrophy with sufficient intensity.

What happens to glycogen use with aerobic training?

Glycogen sparing – greater fat utilization, prolonging performance.

What happens to lactate threshold with aerobic training?

Occurs at a greater % of max (up to 80–90% in highly trained athletes).

What fiber type transition occurs with aerobic training?

Type IIx → Type IIa

What is Low-Intensity Endurance Exercise (LIEE)?

Sustained submaximal intensity requiring lasting ATP.

What is High-Intensity Endurance Exercise (HIEE)?

Sustained or repeated high-intensity (max or near-max), high power outputs, repetitive high velocity.

What aerobic adaptations do sports relying on anaerobic metabolism need most?

Ability to recover quickly and repeat activity at similar effort.

What factors determine endurance performance?

1) VO₂max
2) How close to max the athlete can work (performance O₂ uptake)
3) Running economy/efficiency
4) Lactate threshold

Once VO₂max has plateaued, what explains further performance improvements?

Improvements in exercise economy and lactate threshold.

What type of aerobic activity best improves bone mass?

More intense physical activities( running)

What is required for connective tissue to strengthen?

Necessary strain > everyday activities; complete ROM.

How much can VO₂max improve with training, and in what timeframe?

5–30% improvement within 6–12 months, then plateau.