.VO2max: what do we know, and what do we still need to know?

Area of Science:

• Exercise Physiology
• Cardiovascular Physiology
• Skeletal Muscle Physiology

Background:

• Maximal oxygen uptake (VO2max) is a key determinant of endurance performance, constrained by the Fick equation.
• Classical understanding emphasizes convective oxygen transport, while contemporary research explores peripheral muscle fatigue mechanisms.
• Understanding central integration of cardiovascular and neuromotor control remains an active area of investigation.

Purpose of the Study:

• To review the physiological determinants of VO2max.
• To discuss the role of cardiac output and left ventricular function in elite endurance athletes.
• To explore the factors influencing cardiac phenotype plasticity.

Main Methods:

• Literature review of classical and contemporary research on VO2max.
• Analysis of the Fick equation and its physiological components.
• Examination of cardiac adaptations in elite endurance athletes.

Main Results:

• VO2max is fundamentally limited by oxygen transport, with evidence supporting convective limits.
• Elite endurance athletes exhibit high VO2max primarily due to increased cardiac output, driven by a large, compliant left ventricle.
• This cardiac adaptation facilitates high muscle blood flow and oxygen delivery, supporting sustained high rates of oxidative metabolism.

Conclusions:

• Cardiac function, particularly left ventricular filling and ejection capacity, is crucial for achieving high VO2max in endurance athletes.
• The precise mechanisms and extent of cardiac plasticity in response to training require further investigation.
• Genetic factors and training characteristics likely interact to shape the cardiac phenotype for endurance performance.