I am not quite sure about your question. A MET (Metabolic equivalent) level is simply a unit of energy expenditure. After fitness assessments, exercise recommendations may be made in terms of MET levels based on established tables that link those levels to certain activities.
Here is an excellent article called “Metabolic Equivalents (METS) in Exercise Testing, Exercise Prescription, and Evaluation of Functional Capacity” http://onlinelibrary.wiley.com/doi/10.1002/clc.4960130809/pdf.
Hope this helps.