Final answer:
The most widely accepted criterion measure of cardiorespiratory fitness is the VO2 max, which is the maximum amount of oxygen the body can use during intense exercise, adjusted for body weight.
Step-by-step explanation:
The most widely accepted criterion measure of cardiorespiratory fitness is the maximal oxygen uptake (VO2 max). VO2 max is considered the gold standard for assessing the aerobic capacity of the cardiovascular system, which is the ability of the heart, lungs, and blood vessels to deliver oxygen to working muscles during sustained physical activity. It's expressed as the maximum amount of oxygen the body can use during a specified period, usually adjusted for body weight (milliliters of oxygen per kilogram of body weight per minute). A high VO2 max indicates a high level of cardiorespiratory fitness.
While the Respiratory Quotient (RQ) and energy consumption measurements provide important information about metabolism and can indirectly assess fitness levels, they are not the primary tools. Factors such as heart rates, cardiac reserve, and maximal heart rate (HR) during exercise are related to VO2 max and are often measured alongside VO2 max for a comprehensive evaluation of cardiorespiratory fitness.