Use of a metabolic analyzer allows for testing of Vo2 Max, Lactate Threshold, and Resting Metabolic Rate. This gives you insight to your personal Training Zones which help you train smarter, and race not only wiser but faster. It is common to determine lactate threshold heart rate zones by completing a 30 minute time trial or field test and taking the average heart rate for the last 20 minutes to extrapulate training zones. While this method is much better than nothing at all, it is far from accurate due to the fact that heart rates can be wildly inaccurate due to factors such as dehydration, fatigue/stress, illness, etc.... . A metabolic analyzer measures oxygen uptake and Co2 emmitted while on an ergometer (treadmill or bike trainer) during an 8-12 minute protocol. Lactate threshold is determined at the point where Co2 emmissions sky rocket and fat utilization as energy bottoms out sending you into an anaerobic state. The benefit of being tested with a metabolic analyzer is the ability to dial in your heart rate training zones in coordination with your power and your body's metabolic response to exercise. On top of that, you only have to test twice per year to determine zones and progress rather than completing those annoying time trial field tests every 3 weeks.
