Feat of strength?
Anything of Flash is likely going to be impact/force based. He's not going to have much in the way of lifting, though he does seem to be able to pick up things most humans would struggle with while running, its nothing super impressive for an even a top tier street leveler.
As far as impact goes, pre-flashpoint, he could attain the mass of a star and hit an object with it.
In the recent comics he ran pretty fast
Originally posted by The Sorrow
Hulk shows some superspeed and saves SHIELD Agents by stopping a speeding plane "dead" with one arm, despite it appearing out of thin air and being only several feet away from them:http://media.bestlittlesites.com/images/users/uploads/10300/HULK2012011_int_LR-3-4.jpg
(The humans still seem to be stuck in the same position in the bottom panel when Hulk speeds past them as they were in the panel above)
Merlin casted a spell of banishment and Hulk made it back off of pure speed alone.
http://static.comicvine.com/uploads/original/11113/111134695/4207348-9123453900-40164.jpg
I guess this depends on how you view the word banishment.