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.
Training errors may cause runners to develop iliotibial band syndrome symptoms. Roads are canted or banked with the center of the road higher than the outside edge to allow for water runoff. If a runner always runs on the same side of the road, it produces the same effect on the body as having a leg-length discrepancy.