One thing for certain is you don't have 'tight muscles'. Women have been told that by many a doctor as an excuse for an unexpected outcome after breast augmentation surgery. The truth is that muscle aren't tight, and if they were, it would contribute to faster dropout. Theoretically, very thick and tight skin that may exist at the inframammary fold may inhibit or delay expansion, although properly chosen implants do not exhibit any problems with drop and fluff. Finally, don't be fooled into performing breast implant massage. It does not change any outcome, is not necessary for normal healing, and does not prevent or treat capsular contracture. Further, it is just bad practice to shift the responsibility of a good result into the patients' hands; any unexpected outcome is now the blame of the patient, which is of course, inappropriate and wrong. Best of luck!