Is it possible for internal/permanent sutures of breast implants to tear from stress?

Heavy exertion can certainly lead to tearing of ADM material if not completely healed. Our patients are instructed not to perform upper body exercises for 8 weeks after revision of Acellular Dermal graft material. Please seek your original surgeon for evaluation as soon as possible.

It is quite difficult to tear a suture from feeling nervous. That being said when revising the breast "pocket" usually multiple sutures are used and they can be anchored to the ribs, which may hurt quite a bit. If you have concern that you have "popped" a stitch please contact your surgeon directly so they can examine you in person.

Sutures are occasionally used to revise (make smaller) the size of the internal scar tissue "pocket" that a breast implant is in after a breast augmentation is performed. The size of the pocket can be stretched out by an overly large implant or over dissection of the natural internal ligament "net" that forms the support of the breast gland and also the support of the implant used for augmentation. The sutures are placed into the scar capsule that forms around the implant to make the pocket smaller, and occasionally are also placed into the tissue of the chest wall for added support. However, a fit woman will always be stronger than any suture, and even a hard cough or sudden hard arm pull could break one of those sutures. After revision surgery we ask our patients to be very careful with strenuous activity for 6 weeks to allow for good strong healing to occur. If you are concerned please see your Plastic Surgeon for an examination. 

Mental stress should not impact the sutures, but physical street may. So I would be very careful with the breasts during the healing phase and follow you surgeon's advice.