If musculature is directly related to speed, that would imply that
Belgians, Percherons, and Clydesdales are faster than Thoroughbreds.
Is that in fact, the case? In a similar vein, would a mastiff be expected
to outrun a greyhound or whippet?
Bears can indeed run as fast as horses; they just, AFAIK, can't keep it up
for comparable distances.