I do the isolation exercises on resistance machines and with dumbells that are so frowned upon by PB.
However, I have made progress on these ... in that I can do 10 quasi-push ups now. I can't drop all the way to the ground and back up again, but I can drop halfway down and raise back up again. This is serious progress for me.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.