Permanent distortion of breast implants with pilates and planks?

Because the pectoral muscle covers the top of the implant but not the bottom and outside, activity of the muscle can push the implants to the side or down over time. You should not have to adjust your exercise routine with good enough support but if you don't have to focus on your pecs, that might be a good idea.

In my experience, the size of the implant has more to do with implant displacement than activity.  While it is true that certain strenuous exercises can cause implants to move laterally, I have seen very few cases where exercise could be attributed as the main culprit.  I have seen many examples where too big of an implant in too small of a space has cause the pocket to stretch or rip out to the side causing lateral implant displacement.  Some attribute this to making the pocket too big.  Although that can be a problem, most of us are very careful not to over dissect the pocket, particularly to the outside so as to avoid the problem.  But large implants have to take up space somewhere and the weakest area is to the side.  700 cc is a pretty generous implant so I think you will have to be careful.  I hope this helps.  Best wishes.