THE GOLDEN STANDARD EXPLAINED
VO2 is the golden standard for aerobic fitness and any possible health benefits that may result from being aerobically fit. VO2 can be represented as an absolute physiological measurement or a relative physiological measurement. Abbreviated as AVO2, it represents the overall oxygen consumption of the entire body, while abbreviated as RVO2, it represents the relative amount of oxygen that each unit of mass/weight will receive.
AVO2 is measured in units of litters per min (L/min) while RVO2 is measured in units of milliliters per kilogram per min (mL/Kg/min). Absolute measures often lack the ability to be used to compare between different people and/or different sexes. AVO2 does not allow us as scientists to understand how much oxygen would a specific tissue mass/weight be supplied with, and consume as part of its function.
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RVO2 is the outcome of dividing a person AVO2 by one of three weights possible. The first option is to divide the body's oxygen consumption by body weight (BW). While this calculation is the most common since it is easy to know a person's weight, it includes an inherent error, since it takes into consideration all of the tissues and content of the body that make up the person's body weight, yet do not consume oxygen. Any part of the body or its content that does not use oxygen, is not actually contributing to AVO2 or RVO2. Conclusion - dividing by body weight is easier yet less accurate physiologically.
The second option is to divide oxygen consumption by skeletal muscle mass. Skeletal muscle mass includes the weight of all of the skeletal muscles in a person's body. While this option is more accurate physiologically than the first (division by body weight) option, it is still not the most accurate option physiologically, since it includes the weight of muscles that are not necessarily demanding significant amounts of oxygen.
The third options is to divide oxygen consumption by the actual active skeletal muscle mass, meaning only skeletal muscle mass that is being used actively to move, and is actually and actively significantly consuming oxygen. This option represents the physiological truth the most, yet both the second and third options are very realistic to use on a regular basis since they require finding out a person's muscle mass (total or active), which most likely will require urine or tissue to determine.
A person's oxygen consumption ranges from oxygen consumption at rest (0% intensity; which is greater than zero) all the way to maximal oxygen consumption while at maximal intensity (100% intensity). RVO2 at rest ranges for all humans between 3.3 mL/Kg/min to 3.7 mL/Kg/min. Addressing differences in oxygen consumption at rest as insignificant, we use an oxygen consumption at rest of 3.5 mL/Kg/min as constant for every human independent of any other of their characteristics (sex, age, fitness, etc.).
The average person is regarded as untrained, and presents with an RVO2 of 45 mL/Kg/min, while anything below this value is below average. An RVO2 of 35 mL/Kg/min or less is regarded as poor fitness. World level elite athletes presents with an RVO2 of 80 - 85 mL/Kg/min. Higher RVO2 values can be achieve, yet not naturally (with the help of illegal substances). Any RVO2 value between 45 - 80 mL/Kg/min represents a person that is aerobically trained at different levels. The higher the RVO2 the more aerobically trained, and in theory, the greater the health benefits associated with.
A person's RVO2 depends on many factors that need to align just right in order to result in the greatest RVO2 possible. We need the greatest volume of air to reach the lungs (not get stuck in the airways), the greatest volume of oxygen to partake in the lungs' gas exchange process between the alveoli and the blood stream, the greatest volume of oxygen to bind to the hemoglobin within the red blood cells (RBCs), and the greatest volume of oxygen to be diffuse into the active cells (bind to myoglobin), and the greatest volume of oxygen utilized in the mitochondria (plural).
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