For Michelet, the Renaissance was more a development in science than in art and culture. He asserted that it spanned the period from Columbus to Copernicus to Galileo; that is, from the end of the 15th century to the middle of the 17th century.
Other researchers believe that side stitches are caused by stretching the ligaments that extend from the diaphragm to the liver. When a runner or walker pounds the surface while breathing in and out, he or she stretches these ligaments, and that causes the pain.
Athletes often develop hip bursitis after running up and down hills repetitively. The condition can also be caused by abnormal walking, such as limping, due to an uneven leg length, or arthritis in the back, hip, knee, or other joints in the leg. It can also occur without any specific cause.