Changes

[[File:Boston1910.jpg|thumbnail|left|350 px|The Boston Marathon in 1910]]With the entry of women, the marathon as we know it today had become set. Among the most difficult of the Olympics, the sport has become popular with many amateur runners around the worldworldwide. Because few other sports test both stamina and physical ability, where the mental challenges of running for such a long distance are as significant as the physical ones, it may help to explain why this sport is relatively popular. The sport is increasingly associated with raising charitable funds, as amateurs and professionals use the event to raise funds for their causes.<ref>For more on how today's marathon is popular with many amateur runners, see: Murphy, Sam, and Sam Murphy. 2009. Marathon and Half Marathon: From Start to Finish. London: A & C Black, pg. 165.</ref>

Over half a million runners ran marathon races in 2014 in the US. Interestingly, the over 40 population segment has grown the most substantially in participating in the marathon. Once again, it is likely the physical and mental mentally demanding nature that has pushed the popularity of this sport 's popularity for older athletes.<ref>For statistics on the marathon's popularity, see: Zinner, Christoph, and Billy Sperlich. 2016. Marathon Running: Physiology, Psychology, Nutrition, and Training Aspects, pg. 108.</ref>

For most runners, the a marathon is a one-time event done to challenge one self and possibly raise funds. However, for some amateurs, it is a year-round lifestyle. Runners train for the many major events and the . The marathon has even inspired more extreme running events that have grown in popularity, ranging from ultra-marathons that are over 100 miles in some cases to difficult races that traverse wild terrain and mountainous areas. Medically, running can be addictive, with endorphins perhaps influencing some runners to keep running. Whatever the exact reasons, the trend of long-distance running inspired by the marathon continues to grow. Clubs and group training events can now be found in many places in Europe and the United States in particular.