Is a 510cc saline implant considered large for an extremely active person? (Photo)

At size 36 each 200 cc’s of implant corresponds to 1 cup
size change. From this, you can compute
the volume required to achieve your desired goal. I always recommend small round textured
silicone gel implants placed retro-pectoral since they look and feel more
natural, are more stable, less likely to ripple or have complications needing
revision. Implant profile is irrelevant
in the retro-pectoral position since the muscle compresses it. Large implants such as 510 cc’s will extrude
inferiorly and laterally requiring revision.
Unfortunately, your photograph does not show your breasts directly so I
cannot access if you have drooping. If
you have ptosis a simultaneous lift may be helpful to you.Best Wishes,Gary Horndeski, M.D.

There is a clear connection between large size (350cc or bigger) and complications. Women who get sizes that are in the 400 to 500 cc range enjoy these for a while but often see that the weight, the bottoming out, possible capsule formation, and an overall heavy look is not so desirable. I alway counsel my patients about size and using Vectra 3D imaging show them the potential that is in store for them. Patients always have the final say, but I really try hard to counsel a more reasonable size for them. 

Thank you for the question and picture.  However, despite good intentions, online consultants will not be able to provide you with  meaningful specific advice.  Ultimately, in person consultation with well experienced board-certified plastic surgeons will be necessary. Careful measurements, dimensional planning, and careful communication will be key.
Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery ( regarding breast implant size/profile selection) is:
 
1. Concentrate on choosing your plastic surgeon carefully.  Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you're looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your   desired goals  with your plastic surgeon. This communication will be critical in determining which operation and/or breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "C or D cup" etc means different things to different people and therefore prove unhelpful.
 Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup  size may also be inaccurate.  The use of computer imaging may be very helpful during this communication phase.
3.  Once you feel you have communicated your goals clearly,  allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals.  Again, in my practice, this decision is usually made during surgery.
I hope this, and the attached link, helps.

I think that you need to be evaluated in person to determine if the implant you want is the appropriate size for you.  Answering that here without an exam is impossible.

The difference between 475cc's and 510cc's will not be noticeable for you. However, if your base width is only 12.5 and 13cm a high profile implant still warrants consideration. The moderate profile implant is going to be much wider than what you have in and you will have more breast laterally (on the sides) than you are used to. So it's not your volume choice rather your choice of profile.

I think your concern is valid.  For an active person who runs and lifts weights, a 510 cc implant may be a bit much.  Also, larger implants can make you look heavier if you don't have a long torso.  You may want to visit a plastic surgeon who has 3D imaging like the Canfield Vectra system to help you visualize your result ahead of time.Good luck

Your photo does not show your breasts, so I am unsure whether you have an excess of skin you are trying to "fill out", or whether you are looking for more upper pole fullness.  The larger and heavier the implant, the greater the risk of irreversible stretching and thinning of your tissues, implant bottoming out, etc., which could lead to further and more complex surgeries.  Saline implants, due to their weight and mechanical properties, have, in general, greater risks in regard to stretch deformities and bottoming out than silicone gel implants. I would be cautious about going to so large a saline implant. Discuss with one or more board-certified plastic surgeons so you understand the pros and cons.

I am assuming that what I see in the photo is you in a non-padded bra.  If so, you are not too small.  In fact your volume fits very nicely with the rest of your torso.  The issue is what you mean by "don't fill my breast enough".  If there is residual tissue laxity so that the breast tissue seems to sag from the face of the implant, then a larger implant may help.  If this is not the case (and without either an un clothed photo or direct exam one cannot tell), then a larger implant is not "needed' but only desired.   For someone very active in running and fitness training I would be very careful about being larger.  Many patients note that being overly large makes previously easy exercise difficult.