The maximum oxygen uptake ( VO2max) is the number of milliliters of oxygen, the body can utilize the state of the maximum exertion per minute. The information is given in milliliters of oxygen per minute (ml O2/min ). VO2max can be used as a criterion for the evaluation of endurance capacity of a human being, but only represents the upper limit for endurance performance (cf. below, section " training condition and VO2max " ) and is therefore also referred to as the " gross criterion " in endurance performance.
The absolute VO2max (l / min) did not take into account the body mass. Consequently, large and heavy people have in principle higher values than small and light. Therefore often related to body mass relative maximum oxygen uptake (indicated in ml O2/min/kg body mass), since their significance with respect to the assessment of endurance capacity for sports where the weight and / or volume of the body plays a role ( running, cycling ), is higher. The corresponding values are more comparable even from individual to individual.
The VO2max represents the processes that are involved in the utilization of oxygen in the body:
- Supply of oxygen from the air via the respiratory system
- Transport of oxygen in the blood through the cardiovascular system
- Use of oxygen in the cells of the musculature
- Use of oxygen in the cells of the remaining skeletal muscle, cardiac muscle, smooth muscle, nerve cells and cells of the organs that need oxygen.
Improvement in VO2max
The goal of training in endurance sports is, inter alia, to increase the maximum oxygen uptake. This is achieved through various training methods, mainly by basic endurance training and in the field of anaerobic threshold.
Training condition and VO2max
The focus of the training, however, is the desire to bring the continuous power limits as the respiratory compensation point or the Anaerobic threshold closer VO2max corresponding power.
The VO2max is not directly to the endurance of an athlete. Rather, it shows how strong the maximum oxygen uptake can be increased by extremely high performance. The time required for the instantaneous load oxygen uptake becomes clear below, so that the maximum oxygen uptake usually is achieved with an intensity which can be maintained only a few seconds to about two minutes, the athlete.
Continuous power limits such as the iANS show on the other hand, what intensity an athlete can maintain permanently (it has been at least 20 minutes ).
The percentage of utilization of VO2max on reaching this duration power limit can therefore be regarded as an indicator of the state of training. It reflects, among others, as well the body being capable to coordinate processes that require oxygen, but need to be trained, for example lactate utilization in fast-twitch muscle fibers in the heart and the liver.
Determination of VO2max
On a treadmill or ergometer ( bicycle, rowing, handwheel) an exertion of the body is brought about. By measuring the oxygen content of the inhaled air and the amount of the exhaled air, the VO2max may be calculated.
Alternative determination of VO2max
The VO2 max can be determined via a venous and arterial blood gas determination according to Fick's principle:
HMV = cardiac output, CaO2 = arterial oxygen content, venous oxygen content CvO2 =
The arterial, or venous oxygen content can be determined by means of the arterial and venous oxygen saturation, hemoglobin content and Huefner number.
This measurement is the most accurate, but ( Arterial and central venous catheters for blood sampling system under load ) tend to be used due to the invasiveness in research projects than for routine diagnostics.
Uth -Sørensen - Overgaard - Pedersen estimate
Another estimation method for VO2 max, based on the maximum heart rate and resting heart rate, was of Sørensen et al. formulated. This is defined as:
This equation uses the maximum heart rate ( HRmax ) and the resting heart rate ( HRRuhe ) to estimate VO2 max in ml / min / kg.
Kenneth H. Cooper designed for the U.S. Air Force named after him test to test the endurance of the soldiers. The maximum distance is measured, which can run in 12 minutes the subject. From the distance, the relative VO2 max [ ml / min / kg] can be estimated using the following formula:
D12 = distance in meters, which was run in 12 minutes