Physiology of marathons certain physiological characteristics of marathon runners exist. The differing efficiency of certain physiological features in marathon runners evidence the variety of finishing times among elite marathon runners that share similarities in many physiological characteristics. Aside from large aerobic capacities and other biochemical mechanisms, external factors such as the environment and proper nourishment of a marathon runner can further the insight as to why marathon performance is variable despite ideal physiological characteristics obtained by a runner. The first marathon ever run was an unintentional 25 mile trek performed by Pheidippides. Pheidippides was a Greek soldier who ran to Athens from the
Houston Marathon 19th. The 5K event had close to 5,000 runners while the marathon and half marathon had nearly 13,000 runners each. The races bring crowds of nearly one half million to view the runners. The 1979 edition of the competition hosted the national marathon championship race for men and women. Houston was selected for the women's Olympic Trials in 1992 and held the USATF women's marathon championship in 1998. The half marathon course hosted the USATF Men's Half Marathon Championship from 2005 to 2008, and also hosted the women's event in 2007 and 2008. The 2012 U.S Olympic Marathon Trials for