My body takes several days to recover after each full-body workout. Several things may play a role on this fact (lack of abundant sleep, mid-age, whatever) but in any case it is very noticeable and I sort of accepted it already (there is progress after all).
I am sure whey protein with its fast absorption rate is a great friend of young american-football players full of growth hormone, testosterone and acne. Whey is supposed to release amino acids into the bloodstream faster than any other thing, feeding their efficient recovery abilities.
But, since my muscle repair takes place more slowly, I think I need something quite at the opposite end of the absorption rate spectrum, providing me with a lower but more steady supply of amino acids. If I take whey, it will mostly be excreted as urine and/or converted into fat tissue, not to mention the burden on my liver and kidneys, all for nothing.
Is that right? I have been taking 20-something grams of casein at night during ~10 days now and I might be wrong, but I think it is having a positive impact in my recovery. Muscle soreness disappears faster than usual, and lately I haven't had any joint discomfort (which usually happen in either joint or the other the day after each workout).
I had experienced before with white egg powder, but I didn't notice any change. It is too soon to tell with accuracy, but I have the impression that casein is having a positive impact on my recovery times (remark: the rest of the day I eat natural foods). Not much on the load or volume progress, but on the recovery ability.