The more money that goes into certain sports the more the attraction there will be to the genetically blessed. But fuck that - ever since the cheerleaders started sucking the cock of every touchdown winning jock ever - there's been a reward system in place. Now, much like Rugby and Soccer here, there has been a strength and conditioning coach as a part of the better teams even at school level. So a reward system and weights. Throw in local well-to-dos and businesses sponsoring the training facilities (have you FKIN SEEN some of the school gyms some places have now? TIP FKIN TOP).
Tell me, before PED's, that all that won't attract the top speed and muscle freaks. Then throw in the cash. Top Rugby players here, always (and still) 2nd in the money stakes to the soccer players here, can still earn £100,000 a week. Top teams, not including the bigger scrum halves, average 231lbs bwt now. When you change that to $30m plus a year for a top US ProBall player (about $800,000 a week) then you will, drugs or not, attract a 300lb and fast athlete.
Now include drugs = boom!