Adjustments to weightlifting training

Background
The pectoralis major ("pec") muscle is said to decrease in function and size after surgery. This may lead to reduced shoulder mobility. The fascia of this muscle is removed during a mastectomy. The reason for the removal is to reduce chest wall recurrence. To close the wound after breast tissue removal the skin is "quilted" to the muscle to reduce the risk of seroma formation.  Do these surgical procedures/techniques impact exercise?

Training observations
At 14 weeks post surgery I am attempting maximum lifts. I feel strong after having practiced more squats, more flexibility exercises, and more core exercises, since surgery. Volume training at reduced weights has been going well. Thus lifting the heavy barbell off the floor works, so do cleans. But the overhead portion of the movements do not "feel right," or do not feel the way it was before. And with heavier weights it becomes more noticeable. Here are a few observations:

1. The removal of the breast tissue creates a different balance, equivalent to 1-2kg weight. Thus muscles need to adjust, the brain needs to learn different signals. The proprioceptive sense can be off.
2. In overhead lifts such as jerk or snatch, the latissimus dorsi ("lats"), the muscle below the shoulder blade, spasms. It may be the case that I lean slightly back (observation 1).
3. In snatch or jerk  the elbow turnover is slower than before and elbows are often bent. Bent elbows instead of the "lockout" can be caused by not engaging the lats properly (observation 2).
4. During a split jerk at max weight, the right shoulder may collapse (possibly also of proprioceptive origin).

Lymph nodes were removed from the right side. There is still swelling under the right arm that can increase a day after exercises that are weight bearing on arms, such as push ups.

Plan

• built up deltoid and pec muscles hoping that this will improve the balance, e.g. with push-ups, planks on foam roller, behind the neck presses.
• strengthen back muscles and increase shoulder blade stability, e.g. GHD hip extensions with  or without weights, Sots presses, Good mornings.
• push presses and power snatches at a weight that challenges the feeling of it not being "right"

Ideas and thoughts from the experts (physical therapists, nurses, exercise science students, and others)

• Daily scar massage helps to keep the scar tissue supple and flexible. 
• Fascia is a protective layer around the muscle. Due to the removal the muscle can become more easily irritated. Nerves may have been damaged during the removal process, and thus the brain does not receive expected signals and needs to "retrain."
• Kineseo taping the pectoralis and serratus muscles can help reduce swelling as it gives a signal to the lymph flow.
• A well fitting compression shirt may support lymph flow and reduce swelling.
• A common problem after mastectomy is rotator cuff tendonitis due to overhead movements when the back is not straight. Namely, if tight pec muscles lead to internal shoulder rotation.

References
Most literature focuses on shoulder mobility after breast cancer surgery. The following two references do indicate the relationship of overhead stretch with back and chest muscles.

Stegink-Jansen et al.  Computer Simulation of Pectoralis Major Muscle Strain to Guide Exercise Protocols for Patients After Breast Cancer Surgery. Journal of Orthopaedic & Sports Physical Therapy 2011: 41(6); 417-426. Link to article

Findings: The overhead stretch produced one of the highest strain for clavicular, sternal, and abdominal portions of the muscle. (=meaning that this stretch uses the muscle more)

Muraki et al. Lengthening of the Pectoralis Minor Muscle During Passive Shoulder Motions and Stretching Techniques: A Cadaveric Biomechanical Study. Physical Therapy 2009: 89(4); 333-341. Link to article

Findings: The greatest length of the muscle is achieved with 30 degrees scapular retraction.