In placing the implants under the muscle, does this damage the muscle in any way? What happens to the muscle if the implants need to removed for any reason?
This is a good question. The reasons for any muscle changing in function if it is not used for any reason, injured, the nerves been damaged or the muscle length and therefore its tension has changed. Initially the muscle is damaged because we have to incise it partially to get the implant under it. This is why sub-muscular implants are more painful postoperatively than implants placed directly under the breast. Also initially because it is stretched the muscle will function slightly differently, but nature is forgiving because the muscle will learn to behave as normal after a period of recovery.
I have not detected any long term functional problems with the muscle (called the pectoralis major muscle). However, if you were a professional swimmer, tennis player, athlete (such as a javelin thrower, gymnast) I would not recommend any sub muscular implants to be inserted. For “normal people” in the long term, I do not think that there should be any impediment to sporting activities and every day life. Long term the muscle, I believe, fully recovers.
If the implant is removed the muscle will function as before but I suspect that there will be a relatively short period of full functionally recovery as the muscle gets used to the decreased length and tension after the implants have been removed.