The ischial tuberosity, often referred to as the “sits bone,” is a bony prominence located at the base of the pelvis that frequently becomes a source of discomfort. Pain in this area can be disruptive, affecting simple daily activities like sitting or walking. The pain is usually a localized ache in the lower buttocks, and it often becomes worse with pressure or movement. This discomfort signals an issue with the structures surrounding this weight-bearing bone.
The “Sits Bone”: Location and Function
The ischial tuberosity is a large, rounded projection forming the lower and posterior part of the ischium, which is one of the three bones making up the pelvic girdle. It is strategically positioned to serve as the primary weight-bearing point when a person is seated, which is why it is colloquially known as the sit bone. This structure is essential for stability and support, as it directly transmits the body’s weight to the surface being sat upon.
Beyond its role in supporting body weight, the tuberosity is a major attachment site for several large muscles and ligaments. The most notable attachments are the hamstring muscles—the biceps femoris, semitendinosus, and semimembranosus—which originate from its upper portion. The adductor magnus muscle and the sacrotuberous ligament also connect here. When the knee is bent, the gluteus maximus muscle shifts, leaving this bony area with minimal padding, which increases its vulnerability to pressure.
Sources of Discomfort and Pain
Pain originating from the sit bone area is typically linked to two primary conditions: inflammation of the fluid-filled sac nearby or irritation of the attached tendons. The first common culprit is ischial bursitis, often called ischio-gluteal bursitis. A bursa is a small, fluid-filled sac that acts as a cushion between the ischial tuberosity and the overlying tendons and skin. When this bursa becomes inflamed, usually due to sustained pressure from prolonged sitting on hard surfaces, the condition is known as ischial bursitis. The resulting pain is a dull ache that is often tender directly over the bone and is aggravated by sitting.
The second frequent cause is hamstring tendinopathy, which involves irritation or microscopic tearing of the hamstring tendons where they anchor to the ischial tuberosity. This condition is common among athletes, particularly runners, cyclists, and those involved in activities requiring explosive movements or repetitive hip flexion. The repetitive stress from these activities can overload the tendon attachment point, leading to chronic pain that may radiate down the back of the thigh. Unlike bursitis, tendinopathy often causes pain during muscle activation, such as when running or climbing stairs.
Strategies for Relief and Recovery
Managing ischial tuberosity pain focuses on reducing pressure and inflammation to allow the affected tissues to heal. A simple, yet highly effective, strategy is to modify your seating environment to alleviate direct pressure on the sit bones. Using specialized gel or foam cushions, or even a donut-shaped pillow, can help distribute weight away from the painful area. Adjusting your sitting posture to lean slightly forward, which shifts the weight to the thighs, can also provide immediate relief.
Applying cold therapy, such as an ice pack, can help reduce localized inflammation and numb the pain, particularly during acute flare-ups. Once the inflammation subsides, gentle stretching of the hamstring and gluteal muscles can be introduced to improve flexibility, but care must be taken not to aggravate the pain. Activities that strain the area, like cycling or intense running, should be temporarily modified or avoided for four to six weeks to allow for tissue rest. If the pain persists beyond a few weeks, or if it is accompanied by severe symptoms like weakness or radiating nerve pain, seeking a professional medical evaluation is recommended.