a “met” was derived from the resting oxygen consumption (VO2) for a 70kg, 40-year-old male and its value is 3.5 ml/min per kilogram of body weight. Therefore, a person working at 5 mets would have a VO2 of 17.5 ml/min/kg.
Some laboratories estimate maximum METS from the maximum work rate achieved using the “Bruce” protocol without actually measuring VO2, which may lead to inaccurate results.