Maximum oxygen uptake – VO2max

As the blog post on factors of endurance performance highlighted, maximum oxygen uptake (VO2max) is one of these critical factors.

VO2max formally corresponds to the cardiac output (CO), i.e. the stroke volume (SV) multiplied by the heart rate (HR), and the arterio-venous oxygen difference.

VO2max = CO * AVO2-D = SV * HR * AVO2-D

The maximum oxygen uptake is often also referred to as oxidative capacity as well as gross criterion of endurance capacity/cardio-pulmonary metabolic capacity. As such, it comprises all mechanisms involved in the performance of the body. The underlying mechanism is the ability of the body to produce energy in the form of ATP with the use of oxygen. As a recap, ATP is the universal energy supplier of the cells. In other words: VO2max refers to the (maximum) flow rate (performance) of aerobic metabolism or oxidative phosphorylation. The value quantifies the maximum amount of oxygen that is inhaled per unit of time, is diffused through the lungs into the blood, reaches the active muscles via the bloodstream. There, it is primarily used for aerobic energy production.

The level of VO2max is mainly dependent on the following factors:

  1. Oxygen diffusion capacity of the lungs
  2. Maximum cardiac output per minute, i.e. pumping function of the heart
  3. Oxygen transport capacity of the blood
  4. Capillary and mitochondrial density of the muscles
  5. Enzyme activity in the target muscles

The VO2max is considered a predictive tool and is often used as a talent indicator for future endurance performance. However, especially in performance-homogeneous groups, as often found in competitive sports, this value only allows a rough assessment of the endurance training condition.

Due to its great importance in endurance sports, VO2max should be a mandatory part of a comprehensive performance diagnosis. Ideally, the diagnostics should be performed by experts, carried out in a standardised manner and tailored to the sport in question. Only by keeping the various factors that potentially influence the result constant, including test protocol, preload and time of day, a comparison of the measured values is possible. There are various possibilities for the assessment procedures. Without going into detail about their strengths and weaknesses, these include mixing chamber systems, the Douglas bag principle or breath-by-breath methods. Regardless of the technique, a test protocol is required which allows the aerobic system to be fully loaded in a period of time before the test is aborted for other reasons. Generally, the absolute VO2max is given in ml, the relative VO2max therefore in ml/kg body weight.

Increase VO2max through training

We will elaborate in further blog posts what kind of training is needed to increase VO2max.

amongst others: Joyner, M.E. & Coyle, E.F. (2008). Endurance exercise performance: the physiology of champions. The Journal of Physiology, 586(1), 35-44.