In normal movement healthy joint surfaces glide freely against one another. Stiff joints cause pain because their articulating surfaces lose their capacity to glide freely. Joints can stiffen for many reasons inluding poor postural habits maintained over long periods of time or thickened tissue blocking the joint's articulating surfaces. Stiff joints can be released using a variety of techniques that include deep tissue massage, ultrasound, joint mobilisations and when necessary joint manipulation.