Under-the-muscle breast implants aren’t universally better, but they are the more popular choice for good reason. Placing implants beneath the chest muscle (called submuscular or subpectoral placement) provides extra tissue coverage that hides the implant’s edges, reduces visible rippling along the upper breast, and may lower the risk of scar tissue hardening around the implant over time. That said, this placement comes with its own trade-offs, and the best option depends on your body type, activity level, and goals.
How the Two Placements Differ
In subglandular placement (over the muscle), the implant sits between the breast tissue and the chest muscle. The implant is covered only by skin and breast gland tissue. In submuscular placement (under the muscle), the implant is positioned beneath the pectoralis major, the large fan-shaped muscle covering the upper chest. This adds an extra layer of living tissue between the implant and the skin’s surface.
Most surgeons today use a variation called the dual-plane technique, which is a hybrid. The upper portion of the implant sits under the muscle while the lower portion rests behind the breast tissue. This was designed to combine the coverage benefits of submuscular placement with the ability to shape the lower breast more naturally, especially in women with some breast sag.
Where Under the Muscle Wins
The biggest advantage of submuscular placement is concealment. With an extra muscle layer on top, the implant’s upper edge blends more smoothly into the chest wall. One long-term comparison by a single surgeon found that rippling along the upper breast was noticeably less common in submuscular patients than in subglandular ones. If you’re lean or have naturally small breasts with thin tissue, this matters a lot. Implant edges and ripples become much more visible when there’s less tissue to mask them.
Your surgeon can estimate your tissue thickness using a simple pinch test. If the tissue across your upper breast pinches to less than 2 centimeters, most decision-making guidelines recommend going under the muscle (or using a dual-plane approach) to ensure adequate coverage. Women with thicker tissue, over 2 centimeters, have more flexibility to consider placement above the muscle.
Submuscular placement also tends to produce a more gradual slope from the collarbone down to the breast, which many people find more natural-looking. With subglandular placement, the upper edge of the implant can be more visible, creating a rounder, more obviously augmented look. Whether that’s a pro or a con depends entirely on personal preference.
Where Under the Muscle Falls Short
The most significant downside of submuscular placement is animation deformity, a distortion of breast shape that happens when you flex your chest muscles. Because the implant sits beneath the pectoralis, any chest contraction can push the implant around, causing it to shift upward or to the side and temporarily widening the gap between the breasts. A review of the research found that a median of 58% of patients with submuscular implants experienced some degree of this distortion. The severity varies widely. With the standard dual-plane technique, about 5% of patients had severe animation deformity, while the rest experienced mild or moderate movement that may only be noticeable during exercise or specific arm movements.
This is a real consideration if you work out frequently, especially with chest-focused exercises like push-ups or bench presses. For athletes or very active people, the visible shifting during muscle contraction can be distracting or embarrassing. Subglandular placement eliminates this problem entirely because the muscle sits behind the implant instead of in front of it.
Recovery is also typically longer with submuscular placement. Separating the muscle from the chest wall and stretching it over the implant causes more post-operative soreness. Most patients describe the first week or two as significantly more uncomfortable compared to subglandular recovery. The implants also take longer to settle into their final position, a process often called “dropping and fluffing,” which can take several months.
Capsular Contracture Risk
Capsular contracture, where scar tissue forms a tight shell around the implant and makes the breast feel firm or look distorted, is the most common long-term complication of breast augmentation. It’s widely believed that submuscular placement lowers this risk, and some data supports that idea, though the picture is more nuanced than many people realize.
Research published in the Aesthetic Surgery Journal compared capsular contracture rates across placement options. For smooth implants, the rates were 17.1% for subglandular placement and 7.2% for subfascial placement (a variation of over-the-muscle where the implant goes beneath a thin tissue layer covering the muscle). For textured implants, rates were lower overall: 3.7% subglandular versus 0.9% subfascial. However, neither comparison reached statistical significance, meaning the differences could be due to chance. In studies with follow-up longer than two years, the gap widened somewhat, with textured implants in the subfascial plane showing a significantly lower contracture rate (0.7% vs. 5.5%) compared to subglandular placement.
The takeaway is that placement likely plays a role in contracture risk, but it’s one factor among many. Implant texture, surgical technique, and whether an infection occurs during healing all influence the odds.
Mammograms and Cancer Screening
Any breast implant can obscure some breast tissue on a mammogram, but submuscular placement generally interferes less. When the implant sits behind the muscle, the mammography technician can more easily push the breast tissue forward and away from the implant to get a clearer image. With subglandular implants, the implant is closer to the breast tissue itself, making displacement harder. If you have a family history of breast cancer or expect to rely heavily on mammographic screening, this is worth factoring into your decision.
Which Placement Fits Your Body
The “better” choice depends on several individual factors. Under the muscle tends to be the stronger option if you have thin skin, little natural breast tissue, or want the most natural-looking result with minimal visible implant edges. It’s also generally preferred for people getting larger implants, where the extra coverage helps prevent the implant from looking or feeling obviously artificial.
Over the muscle may be preferable if you have enough natural breast tissue to provide adequate coverage on its own, if you’re very physically active with significant chest muscle use, or if you want a shorter, easier recovery. It can also produce better results for people with strong pectoral muscles, since submuscular placement in very muscular individuals can lead to implant distortion during flexion.
The dual-plane approach has become the default for many surgeons because it splits the difference. You get muscle coverage over the upper implant, where visibility matters most, while the lower breast drapes naturally. Newer muscle-splitting variations of this technique have brought severe animation deformity rates down to around 5%, addressing the biggest complaint about traditional submuscular placement. For the majority of patients, particularly those with moderate tissue thickness and no extreme athletic demands, dual-plane placement offers the best balance of natural appearance, long-term stability, and complication profile.