What a great business opportunity ... if there were some simple in-home test you could perform with your saliva or urine that could give you an objective measure of your recovery status. There might be some useful information in a before/after MRI or muscle biopsy, but that's not practical.The problem is that there's no real quantifiable way (that I'm aware of) to determine if you're fully recovered or not, so we just end up going on feeling alone. Am I the type that will recover in 4 days? Or the one that might need 10 days? Who knows? The only tangible sign that we haven't fully recovered yet is muscle soreness but that doesn't always happen with every workout, so I don't think that going on muscle soreness, or lack thereof, is a very reliable indicator either.