Are breast implants under the muscle distorted from certain movements during exercise/weight lifting?

Everyone will have some level of distortion, to some it is irrelvant, some a nuisance and some a huge deal. If you are big into weights I suggest a smaller textured implant above the muscle

Thanks for your question-- Any implant in the subpectoral position can exhibit a dynamic deformity when you flex your pectoral muscles.  The easiest way to test this yourself is to press your palms together while facing a mirror.  By watching the position of your implants and sometimes the nipple position, you may notice this "dynamic deformity".  "Dynamic" because it is only present with movement.  When the pectoral muscle is relaxed, this deformity is not seen.  This is often a result of either inadequate release of the pectoral muscle low in the pocket, or a result of the edge of the muscle healing too tightly to the overlying breast gland/skin.  When the pectoral muscle flexes, the skin and breast are retracted, and the implant is pressed laterally.  This doesn't happen to every woman, and the severity of the defect varies.  Most women barely notice this.  Others may seek revisional surgery to release these attachments.  The best way to avoid it all together, especially in female bodybuilders who flex these muscles frequently, is to place the implant in the subglandular (above the muscle) position.  You may not be bothered by this harmless finding enough to want another surgery.  Besides, the improved soft-tissue coverage of the implant and the lower risk of capsular contracture are reasons to keep the implant in a subpectoral position.  Best regards!

Attention to detail during implant pocket dissection is of utmost importance. If the inferior origin of the pectoralis major muscle is not completely released across the entire length of the inframammary fold, two problems occur. 1) The patient will end up with an animation deformity, meaning that when the pectoralis major muscle actively contracts the implant is squeezed upward, or outward, or both. 2) The other problem is that the pectoralis major muscle unreleased at its inferior origin will hold the implants too high producing a very full in the upper pole appearance, and a very inadequately augmented lower pole appearance.My website contains an entire section devoted to breast augmentation for fitness models and body builders.   

I do many weightlifters, fitness competitors and bodybuilders and in my experience, with submuscular placement, the "distortions" are only during the flexion movement. This is natural as the pectoralis is compressing the implant.