The indentations sometimes visible on the lower back, just above the curve of the buttocks, are commonly known as Dimples of Venus or sacral dimples. Formally termed fossae lumbales laterales, these symmetrical depressions are a result of underlying physical structure. Their presence raises questions about how they form and what can be done to make them more noticeable. This article explores the anatomy responsible for these markings, the role of body composition in their visibility, and exercises that can enhance the definition of the surrounding area.
The Anatomy Behind Lower Back Dimples
Lower back dimples are a direct consequence of a unique anatomical feature, not muscle development. The indentations are created by short, fibrous ligaments that connect the skin and underlying tissue directly to a specific point on the pelvis. This connection anchors the skin, creating a depression at that site.
The bony landmark involved is the superior posterior iliac spine, part of the large ilium bone of the pelvis. The dimples sit superficial to the sacroiliac joints, where the sacrum meets the ilium. Because the skin is tethered to this bone structure by the short ligament, the surrounding tissue, fat, and muscle contour around the fixed point, forming the characteristic depression.
The presence of these anchoring ligaments is determined primarily by genetics, meaning the underlying structure is something a person is born with. If the specific ligamentous connection to the iliac spine is not present, it is not possible to create the dimples through weight loss or exercise. For those who possess the anatomical structure, these dimples are present from birth, and efforts focus on revealing the existing indentation.
The Role of Body Composition in Visibility
For individuals with the anatomical predisposition for lower back dimples, the primary factor determining visibility is the amount of subcutaneous fat in the lumbar region. The depression created by the tethered ligament can easily be obscured by a layer of fat tissue. Reducing the thickness of this layer is the most effective way to make the dimples more apparent.
The visibility of these structures improves as a person achieves a lower body fat percentage. Studies suggest that for existing dimples to become noticeable, women often need to be in the range of 18–22% body fat, and men in the range of 25–32% body fat. These are general estimates, and an individual’s personal fat distribution pattern will influence the result.
Fat loss cannot be targeted to a single area of the body, a concept often called “spot reduction.” The body determines where it loses fat based on genetics and hormonal factors, not the muscle groups being worked. Therefore, reducing the fat layer over the lower back requires a sustained, overall reduction in body fat through consistent energy deficit and physical activity.
Achieving a lower body fat percentage involves balancing energy intake with energy expenditure. This typically means adopting a nutritious diet that promotes a moderate calorie deficit and incorporating regular cardiovascular exercise. Focusing on a healthy rate of overall fat loss, such as 0.5 to 1.0 pound per week, is a more sustainable strategy for revealing the dimples than attempting to target the lower back alone.
Targeted Exercises to Enhance Definition
While exercise cannot create the dimples themselves, strengthening the muscles that surround the lower back and pelvis can enhance their appearance. Developing the gluteal muscles, core stabilizers, and lower back musculature improves overall posture. This improved posture and added tone provides a more defined backdrop, maximizing the visibility of dimples revealed by low body fat.
Glute Bridges
Glute bridges are effective for targeting the gluteus maximus, the large muscle responsible for hip extension. To perform a glute bridge, lie on your back with your knees bent and feet flat on the floor. Press through your heels to lift your hips until your body forms a straight line from your shoulders to your knees, squeezing the glutes at the top of the movement. This exercise strengthens the posterior chain, which includes the area directly below the dimples.
Superman Exercise
The Superman exercise is a direct way to strengthen the erector spinae muscles, the long muscles that run vertically along the spine. Lying face down on the floor, simultaneously lift your arms, chest, and legs a few inches off the ground, engaging the lower back muscles. This action strengthens the spinal support system, which contributes to a more upright and defined posture.
Bird-Dog Exercise
The Bird-Dog exercise focuses on core stability and controlled movement of the lumbar spine. Start on your hands and knees, then slowly extend one arm straight forward and the opposite leg straight back, keeping your back flat and level. The controlled engagement of the core and lower back musculature helps to tone the entire region, potentially framing the dimples and improving their visual prominence.