Blood volume is considered the limiting factor in athletic performance due to its ability in delivering adequate oxygen to working muscles

The cardiovascular system is considered the limiting factor in athletic performance due to its role in delivering adequate oxygen to working muscles

The sympathetic nervous system is considered the limiting factor in athletic performance due to its ability to increasing heart rate

The pulmonary system is considered the limiting factor in exercise performance due to its role in ventilation and gas exchange

Training has no influence on cardiac output at rest but increases during incremental exercise.

Training increases cardiac output at rest but has no influence at maximal exercise.

Training increases cardiac output at rest but not not during incremental exercise.

Training has no influence on cardiac output at rest and at maximal exercise.

Reduction of NAD+

Oxidation of FADH2

Reduction of FAD

Oxidation of NADH

The maximal oxygen diffusion within the lungs during exercise 

The maximal blood oxygen saturation during exercise 

The maximal rate at which oxygen can be transported from the body surface to the cytoplasm and mitochondria of exercising muscles

The maximal inspired oxygen volume during exercise 

Withdrawal of vagal tone through decreased parasympathetic activation and increased sympathetic activation.

Withdrawal of vagal tone through increased parasympathetic activation and increased sympathetic activation.

Increased vagal tone through decreased parasympathetic activation and increased sympathetic activation.

The parasympathetic nervous system is the only activated pathway responsible for increased heart rate during exercise.

Stroke volume increases during exercise to a maximum of 80% VO2 max

Stroke volume is reduced by 25% during exercise

Stroke volume is maintained throughout exercise

Stroke volume increases during exercise to a maximum of 60% VO2 max

Renin-angiotensin-aldosterone axis

Baroreceptors in the aortic arch

Arterial chemoreceptors

The kidneys

Ventilation increases disproportionately greater than the change in oxygen consumption at greater than 65% of VO2 max. 

The relationship is linear across all exercise intensities.

Endurance training reduces the inflection point where ventilation increases disproportionately to oxygen consumption. 

In normal healthy individuals, ventilation is the primary limitation for maximal workrate compared to other physiological variables.

The point where ventilation decreases despite increasing workload

The point where ventilation increases disproportionately to oxygen uptake

The point where VO₂ max is reached

The point where tidal volume plateaus

Decrease in systolic blood pressure and increase in diastolic pressure 

Increase in blood volume and decrease in cardiac output  

Increase in total peripheral resistance and blood volume 

Decrease in total peripheral resistance and increase in cardiac output