Monitor Fitness By What You Can DO

From Slowtwitch

Rich Strauss from EnduranceNation.com comparing the measurement of bike fitness using wattage versus blood lactate testing:

There are other methods but what is important is that they are a measurement of what you can DO, not what your blood chemistry, gas exchange, whatever says is going inside your body. Think "I can bench 250 lb" vs "I breath into a tube/get my finger pricked while I'm on the bench. SmartGuy sez that at chemistry/gas marker X I have 250lb on the bar.