You might think you’ve already discovered the many ways to test your performance and fitness levels, but we want to recommend one more; Metabolic Efficiency Testing.
The VO2 Max test is the most common and measures how much oxygen you use.

3 Energy Systems of the Body

ATP-CP system – Used for short bursts of exercise up to 30 seconds at 95%.
Anaerobic system – Also known as the Lactic Acid energy system, used for intense bursts of exercise of 45-60 seconds.
Aerobic system – Uses lower exertion level energy, combining fats, proteins and carbohydrates to produce the energy for muscle movement.

Metabolic Efficiency Test

This test is a way to determine the actual carb and fat combinations at any level of intensity. It is also carried out in the same manner as a VO2 Max test.
Learn more here, http://en.wikipedia.org/wiki/VO2_max