Can I exercise my chest muscles with weights after explantation?

hello Andrezam31  It is important that you not engage in strenuous activities in the first three (2-3) weeks after surgery. Aerobic exercise will raise your blood pressure, which could cause late bleeding and harm your result. If your job keeps you sedentary, you may return to work when you feel comfortable, several days after surgery. Once you begin exercising again, start gently and let your body tell you what it can tolerate. Don’t rush!! #post-op #exercise

Since you are 8 months after explantation, you should be able to safely exercise your peck muscle. The distortion in the muscle you have mentioned during exercise is most likely related to a partially torn lower pectoral muscle torn away from its lower sternal insertion, which should have been repaired during explantation. 
Christian Drehsen, MD

After breast explantation surgery, it's important to approach exercise with caution. Generally, you should wait until your plastic surgeon clears you for physical activity, as the timeline can vary depending on your individual healing process.
Typically, plastic surgeons recommend waiting at least 6-8 weeks before resuming more intense activities, including chest exercises with weights. When you do start exercising, begin with lighter weights and focus on proper form to avoid straining the chest area. Always follow your plastic surgeon's advice recommendations and listen to your body to prevent any complications.

Since your surgery was 8 months ago it should be fine for you to begin chest exercises.  It most likely will not have an impact on your distortion one way or the other however.  You may wish to return to your plastic surgeon regarding your concerns.

What you are describing is known as animation deformity and results from the pectoralis muscle pulling on the capsule where your breast implant previously resided. In my opinion, exercise should not cause any problems at 8 months post-op and should not worsen any deformity (except while you are exercising of course). It may be possible to perform a revision surgery to decrease the degree of animation deformity. However, I would seek several opinions from qualified plastic surgeons before embarking on additional surgery.