" Running competitions have probably existed for most of humanity's history, and were a key part of the ancient Greek Olympics, as well as the modern Olympic games. Events are usually grouped into several classes, each requiring substantially different athletic strengths and involving different tactics, training methods, and types of competitors . Running affects not only the body, but the mind as well. Runners who finish a great run are often said to have a "runner's high" - a strong feeling of accomplishment and pride. Some sources point to the origin of a runner's high being increased endorphin production as a result of exercise. Running injuries There are many injuries associated with running (due to it being a high impact activity). Common injuries are "runner's knee" (pain in the knee), shin splints, pulled muscles (especially the hamstring), "jogger's nipple" (soreness of the nipple due to friction), twisted ankles, and Iliotibial Band Syndrome. Running Training Ultra The most common running related injuries are due to over-use. Repetitive stress on the same tissues without enough time for recovery or due to improper form or muscle imbalances, leads to many of the above. "

" Above a certain pace, running is a more efficient form of locomotion (requires less effort). Below that pace, running is less efficient than walking and makes no sense as a means of getting from point A to point B. A courier delivering a message on foot over 60 miles of road would expend more energy jogging the distance at a 13 minute mile pace rather than briskly walking it at the same pace. Slow jogging is pure exercise, with no practical application. Because jogging is inefficient, it's often associated with poor form. Joggers, or runners who are jogging, sometimes move in ways that wouldn't be done in a competitive running situation: excessively bounding into the air, landing heavily on the heel, carrying the arms too high, and so forth. For these reasons, "jogger" and "jogging" are considered derogatory terms by some athletes who consider themselves runners. Running Training Guide Other people use the terms "running" and "jogging" interchangeably, and see nothing derogatory about "jogging". Jogging is also used for active recovery intervals during interval training. "