The SI joint is most stable against forces that are perpendicular to its surfaces. When standing, force travels through the legs and pelvis, shifting to a horizontal plane that stabilizes the SIJ. However, when sitting, the body weight is transferred to the sit bones, creating a destabilizing force on the SI joint. Repetitive stress can lead to microtears in the ligaments that support the SI joint, causing pain and tightness. Wearing a Serola SI Belt while seated can reduce stress on the SI joint and relieve SI joint pain.