What is the meaning of the measurement met?

Answer: MET (Metabolic equivalent of task) is the measurement technique that is based on the ratio of the energy that is being spend by an individual by any physical activity to the energy spent by individual sitting in quiet position.

This ration has some reference in which is ratio is measured. The energy being measured in the activity time of the person considers his/her relative mass at that time. This relative mass is compared in accordance with the oxygen amount of 3.5 ml per kg/min that is almost equal to energy of the person in the sitting position.