" The runner who may just have completed a fast 400 meter repetition at a sub-5-minute mile pace, may drop to an 8 minute mile pace for a recovery lap. The jog might be carried out in much poorer, looser form whose purpose is to "shake out" the body and maintain circulation to eliminate the waste products of exercise metabolism . Competitive running Perhaps the most basic of athletic contests, running races are simply contests to determine which of the competitors is able to run a certain distance fastest. Today, competitive running events make up the core of the sport of athletics. 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. Asics 2100 Running Shoes 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. "

" Special trails that combine them are called trim trails. Some people define jogging as an inefficient form of running which, for the given individual performing it, and all other conditions held constant, is less efficient than walking. 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. Asics Gt 2100 Running Shoes 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. "