Maximum oxygen consumption (VO2max) represents the individual’s maximum capacity to synthesize energy in the presence of oxygen. It is, possibly, the most widely used parameter in physiological assessment, whether it is focused on assessing performance in athletes or focused on health.
To measure this important parameter, ergometers are used, usually cycloergometers (stationary bicycles) or treadmills in which the individual exercises at increasing intensities connected to an electrocardiogram measurement and a gas analyzer that measures the volume of air that moves and the composition of oxygen and CO2 that it has.
When we perform an incremental exercise (in which the intensity increases) from rest to our maximum capacity for physical exertion, we observe how each increase in the intensity of exertion requires a greater production of energy and imposes an additional load on the capacity of individuals in terms of aerobic metabolism, this is energy production (in the presence of oxygen).
Thus, we need to consume more oxygen to meet the demands of exercise and to be able to generate enough energy to maintain it. This oxygen consumption (VO2) increases in direct relation to the imposed workloads, until a time when it stabilizes and reaches a “plateau”, in which no matter how much we increase the intensity, the oxygen consumption can no longer increase. This is the maximum oxygen consumption (VO2max).
It represents the maximum capacity of the individual to synthesize energy in the presence of oxygen.
Additional work can only be done without using oxygen, by another route in which lactic acid is produced, acidifying the environment and leading to fatigue that prevents continuing.
To measure this important parameter, ergometers are used, usually cycloergometers (stationary bicycles) or treadmills in which the individual exercises at increasing intensities connected to an electrocardiogram measurement and a gas analyzer that measures the volume of air that moves and the composition of oxygen and CO2 that it has.
The measurement of VO2 max allows us to assess, not only the energy expenditure and the functional capacity of the individual, but also the set of devices and organs involved in the uptake, transport and use of oxygen: respiratory system, cardiovascular and metabolic-muscular system respectively. Vo2max has been described as an indicator of cardiorespiratory health, morbidity and mortality in the general population.
Age: increases to 20 years, remains stable between 20 and 30 and begins to decrease from 30 to an average of 10% per decade. This decrease is less in those people who perform physical exercise throughout their lives.
Sex: from puberty there is a difference of 15-30% in favor of men at the same weight and degree of training.
These differences seem to be due to their lower percentage of lean mass and higher fat, lower total blood volume, lower systolic volume values (volume of blood expelled by the heart in each beat), different use of substrates to produce energy and thermoregulation (1).
Hereditary / genetic factors: it seems that this factor can explain up to 50% of Vo2max.
In fact, it is known that this inheritance is fundamentally maternal. We also know that it not only influences the maximum value of Vo2 but also its “trainability” (2).
The size and body composition. It explains up to 70% of the differences between subjects, especially lean mass, which is the one with the most metabolic activity and the one that consumes the most oxygen.
The state and physical condition of the individual. Training can allow improvements of 20 to 50%, being greater the more sedentary the subjects. However, when it comes to well-trained athletes, the room for improvement is much smaller.
When the cardiovascular system is subjected to periodic efforts maintained for a sufficiently long period of time, it undergoes modifications that are called adaptations of the cardiovascular system to effort.
It is estimated that 10 days of training already allow finding adaptations consistent with increased cardiac output (amount of blood pumped by the heart towards the aorta per unit of time) and stroke volume.
The adaptations depend on the type of exercise – predominantly aerobic or strength -, intensity, duration of exercise and years of training.
Continuous exercise has direct effects on the myocardium consisting of improving contractile function, increasing ventricular size at the end of the filling phase, resting bradycardia, improving the use of energy substrates and improving of antioxidant capacity.
Regular resistance training produces a reduction in systolic blood pressure at rest prior to exertion, at maximal exertion, and during recovery from exertion. Power and high intensity training has also been shown to significantly lower blood pressure.
Of considerable clinical interest are the observations that chronic exercise makes the myocardium less susceptible to the deleterious effects of acute ischemic events and may be effective in preventing and / or reversing many cardiac functional deficits that occur in the context of high blood pressure, age advanced and myocardial infarction.
At Marcare Clinic, we are aware of all these benefits that physical exercise has on our cardiovascular health – and in many other areas – and we want our patients to reach their full health and performance. For this reason, we carry out these tests to determine their maximum oxygen utilization capacity, and we repeat them evolutionarily so that both we and the patient can see with objective data how our global treatment program has improved their capacity.
At Marcare Clinic we take care of reviewing, maintaining and offering a quality health service in Hamilton, Ontario.
If you need to visit your doctor for a general medical review or to receive advice on how to improve your quality of life, do not hesitate to contact us.
