What is the consensus on exercising when one has a seroma?

BRUISING AND SWELLING: Bruising and swelling are normal and
usually increase slightly after the removal of any tape or foam. The bruising
will decrease over 3-4 weeks, but may last as long as 6 weeks. The majority of
the swelling will be gone within the first 3-4 weeks. However, it may take 6-9
weeks to disappear completely. The compression garment helps reduce the
swelling, and the longer it is worn, the more quickly you will heal.

NUMBNESS: It is normal to experience numbness around the areola and
chest. As your body heals, you may notice random bursts of pain in your chest.
This is usually a sign that the numbness is subsiding.

LUMPINESS: As you heal, the area may feel “lumpy”
and irregular. This, too, decreases with time, and massaging these areas will
help soften the scar tissue.

ACTIVITIES: If your work keeps you sedentary, you
may return whenever you feel up to it. If your work is strenuous, wait until
your work activity does not cause pain. Wait at least 4 weeks to begin aerobic exercise.

As with all operations, pain and discomfort varies greatly from
patient to patient. Generally, one should expect that pain medication will be
required for the first several days. Continuing discomfort can last varying
amounts of time.

Now, if it has been determined that you have a seroma and that issue is being treated by your surgeon it would be best to consult with him before entering into any heavy exercise schedules to make sure that nothing with outweigh your healing process.

4 cc's is a very small amount. You should discuss the care with your surgeon, he is the one most familiar with your care.