When sitting for long periods, many people experience discomfort or pain in the side of the body, often called flank pain. This pain, which can be felt anywhere from below the ribs to the hip and buttock area, is frequently exacerbated by sustained, static postures. While this experience is common and typically resolves with movement, it should prompt an investigation into its source, as the side of the body houses both muscle structures and internal organs. Understanding whether the pain is muscular or organ-related is the first step toward finding relief.
Identifying the Pain Location
The precise location of the discomfort provides the most immediate clue about its origin, helping to differentiate between musculoskeletal and visceral causes. Pain felt in the upper flank, around the lower rib cage, often points toward issues with the intercostal muscles or the rib joints. These muscles are involved in breathing and can become strained from persistent slouching.
Discomfort localized to the lower flank, between the bottom rib and the top of the hip bone, is commonly associated with muscle strain, specifically the Quadratus Lumborum (QL). Pain originating deep in the hip or buttock, which may radiate down the leg, suggests irritation of the sciatic nerve or Piriformis Syndrome. Pain from internal organs, such as the kidneys, usually presents as a deeper, more generalized ache in the lower back and flank area.
Common Musculoskeletal Triggers from Sitting
Prolonged, static sitting places specific strain on the muscles responsible for stabilizing the trunk. One common muscular culprit is the Quadratus Lumborum (QL), a deep muscle connecting the bottom rib to the pelvis and lumbar spine. Consistently sitting with poor posture, especially favoring one side, causes the QL muscle to become shortened and tight, leading to persistent side pain.
Slouching forward causes the upper back to round, pulling the rib cage downward and compressing the abdominal cavity. This position puts chronic tension on the intercostal muscles, which are essential for respiration. The resulting tightness can manifest as a sharp, localized pain in the side or rib area, often worsening with deep breaths, coughing, or sneezing.
Sustained pressure on the gluteal region from a firm or improperly designed chair can also irritate the sciatic nerve, which passes near or through the piriformis muscle in the buttock. This condition, known as Piriformis Syndrome, often causes a deep ache in the hip or buttock that intensifies while sitting and may produce a shooting or burning pain down the back of the leg.
Internal Health Conditions That Cause Side Pain
While musculoskeletal issues are the most frequent cause of sitting-related side pain, discomfort in the flank area can also signal a problem with an internal organ, known as visceral pain. The kidneys are situated in the posterior abdomen, and conditions like kidney stones or infections can cause pain often felt in the lower flank and back. Kidney pain tends to be a deeper, persistent ache that does not change significantly with body position or movement.
Flank pain accompanied by other symptoms indicates the cause is internal and requires prompt medical attention. A kidney infection, for example, is associated with fever, chills, and painful or frequent urination. Sudden, severe pain that comes in waves, or the presence of blood in the urine, suggests a kidney stone moving through the urinary tract.
Digestive issues can also cause referred pain in the side, particularly gas trapped in the colon or symptoms from Irritable Bowel Syndrome (IBS). Pain from the liver or gallbladder, located on the right side of the upper abdomen, may radiate to the right flank and back. Visceral pain is often vague and diffuse, and it may be accompanied by nausea, vomiting, or changes in bowel habits, which helps distinguish it from a muscle strain.
Strategies for Relief and Prevention
The most effective strategy for preventing side pain while sitting is to introduce dynamic movement and reduce the duration of static posture. A proper ergonomic setup ensures the body is supported in a neutral position, minimizing strain on the QL and other stabilizing muscles. This includes adjusting your chair height so your feet rest flat on the floor, using a lumbar support to maintain the spine’s natural curve, and positioning the monitor at eye level to prevent forward head posture.
Regular movement breaks are essential to relieve the pressure and strain that accumulate during prolonged sitting. Employing the “20-20-20 rule”—standing up and moving every 20 minutes for at least 20 seconds—helps restore blood flow and reset muscle tension. Targeted stretching can directly address the tight muscles often affected by sitting.
To relieve the Quadratus Lumborum, try a seated side bend, reaching one arm overhead and gently leaning away from the painful side to stretch the torso. For hip and buttock discomfort, a gentle hip flexor stretch, such as a kneeling lunge, can help lengthen the muscles shortened from sitting, reducing pressure on the sciatic nerve.