Probably no difference, really.
How much protein, from your diet, do you think actually goes to building skeletal muscle? And if you do train hard, really, how many grams of protein per training session are you really going to lay down as new muscle tissue? 10-20 grams, if you're extremely lucky.
Most of the protein we over-eat goes towards helping the body accelerate protein turnover (the more you eat, the faster the body turns over its tissues...it's generally wasteful but you send the metabolic signal by overeating protein). You could get by eating far less than 1g/lb of bodyweight, which is excessive.
Not that there's anything wrong with eating too much protein either. It is expensive, mind you.
Furthermore, a skeletal muscle turns itself over about once ever 30 days or so. So let's say you've got 10lbs of muscle in your legs. You can't look at it the way I'm going to explain here, because the human body isn't a bomb calorimeter, but bear with me...
You'd need 4540 grams of protein per month to turn over your legs. You'd need an additional 10 grams per week to support your leg training. So, that's 4540 + 40. That's less than 1% of your protein that you need going to new growth, and the other 99.2% going to tissue maintenance.
So really, eating extra protein for extra growth is a rounding error. Completely over-thinking the details.
Bear in mind, also, that strength training is a powerful anti-catabolic (almost drug-like in its effects on the metabolism). So doing any strength training in the gym will have a whole-body anti-catabolic effect, likely preserving the muscle tissue you do have in your legs. For example, it's near impossible to work your back without training legs. It's near impossible to train your chest without training legs (they brace you during the press).
Were you trolling with the question, Gal, or were you questioning seriously?
BTW, most of my above comments go guys who've been training for a year or two and are nearing their genetic limits.
And of course, drugs change the equation.
