Most of the top sprinters not only today but throughout the history of the sport show a balanced and even distribution of mass.
Exceptions seem to be lots of local sprinters ,and european sprinters in general, who carry lots of weight in the thighs but very little in the upper-body. Also there are people who gain weight easier in either the upper- or the lower-body.
How important are an even distribution of mass ,and should this have precedence over gains in strenght/hypertrophy?
What I mean is this:
To me it seems like you should strive for an even distribution of body-mass at all times ,introducing or avoiding hypertrophy as the situation merits. Why then does many choose to neglect their upper-body and to become unproportionate?
(Ben Johnson and Carl Lewis ,however differently buildt ,both where very proportionate.)
Many mistakenly believe that the upper body only has a minor role in sprinting. Notice these same people are never particularly quick either.