Final answer:
Physiological criteria for having attained VO2max include a plateau in oxygen consumption, heart rate reaching near maximum levels, no further increase in blood lactate concentrations, and a high respiratory exchange ratio. These indicators show that the body has reached its limit in oxygen uptake during exercise. Individual factors and measurement tools like a pulse oximeter play roles in determining VO2max.
Step-by-step explanation:
The physiological criteria for having attained VO2max include several physiological markers. One key indicator is when there is a leveling off or plateau in oxygen consumption despite an increase in exercise intensity. This indicates that the body's maximum capacity to consume oxygen during exercise has been reached. Another criterion is when the heart rate (HR) reaches a level close to the individual's maximum predicted heart rate. During peak exercise, heart rate can significantly increase, and in healthy young individuals, HR may rise to about 150 beats per minute (bpm), and stroke volume (SV) can increase to approximately 130 mL.
This could lead to a cardiac output (CO) of around 19.5 L/min, which is 4-5 times the resting rate. However, top cardiovascular athletes at peak performance can reach an increase of resting CO by 7-8 times. Additionally, reaching a VO2max can also be inferred when there is no further increase in blood lactate concentrations with an increase in workload, signaling the inability to clear lactate efficiently. Finally, a high respiratory exchange ratio (above 1.10) and a plateau in carbon dioxide production can also signal that VO2max has been attained.
It's important to note that these criteria could vary slightly among different individuals and are influenced by several factors including the individual's age, sex, fitness level, and specific training adaptations. The use of non-invasive tools like a pulse oximeter to measure the amount of oxygen in the blood is also useful in determining VO2max levels and understanding a person's metabolic rate.
Intense muscle activity creates an oxygen debt, requiring increased oxygen intake to restore energy substrates and clear the byproducts of anaerobic metabolism, such as lactic acid, which ties back to the concept of reaching VO2max during exercise.