all of your questions were already addressed in this thread....
Your mind is still wrapped around someway giving credit to slave masters - when I'm saying look at the horror of the system they created look at what they got away with. Its not a good thing that we were bred for work - NONE of it should have ever happened!
I gave you a fact that you chose to cower from and ignore:
there is a much higher concentration of fast-twitch muscle fibers (and Actinen A) (+/- 70%) in populations of North American and Caribbean slave descendants than any other group
fyi - there are no pure blacks... we all have varying degrees of white ancestors - but there are recessive genetic traits and then dominant genetic traits, most of the west african traits are dominant, selective breeding worked real hard to make desired dominant traits the common traits (more likely to occur). preventing slaves from reproducing if they appeared to carry the recessive traits was very effective.
With hard living conditions and malnutrition -if a male didn't develop he was castrated by 15... if a female wasn't developed or strong enough to bear children she died trying or never had children- that meant only the heartiest of us were allowed to pass on our genes - so do you know that TODAY that even with the poor nutrition and medical care in the hoods and rural areas on average we still develop muscle and bone with higher density than any other race or group? higher than SubSaharan Africans too.
Also studies show that nutrition directly impacts a child's ability to learn, but on average even with poor nutrition, when taught at the same level as the privileged our kids still excelled or held status quo while the dirt poor whites given the same opportunity failed to compete.
If you truly wanted to debate this or wanted answers - you would read the 2 posts I quoted or even better read this thread -
@geechiedan (who agrees with you) unwittingly answered some of your questions by posting records of husbandry and common practices of selective breeding
your reply doesn't sound like you know that the slave trade lasted for almost
4 centuries? (how many generations is that?) vs slaves being freed only 150 years ago (how many generations since 1865?) Do you think that the effects of selective breeding will change in such a short time? Genetics doesn't work like that
(by what logic would you ask about slave masters and future athletes?) They weren't breeding to create athletes, they wanted profits - so they bred for what fetched the best price and made the most production - strength size and fertility - but the unintended results of that are clearly seen in today's athletes - also - they kept very detailed records of each slave's productivity.