According to Running USA, running participation generated yet another banner year in 2013, with total running event finishers in the U.S. climbing 22.5 percent to 19.0 million. The gains were led by non-traditional running events, half-marathons and women runners in general, according to the 2014 State of the Sport – Part III: U.S. Race Trends report.

With 300 percent finisher growth since 1990, Running USA said the findings show “the Second Running Boom is still going strongly as it enters its third decade.” In 1990, there were 4.8 million finishers.

By gender, female finishers grew 24.6 percent to 10.8 million from 8.7 million, representing 57 percent of total finishers versus 56 percent in 2012. Women finishers began exceeding men in 2010. In 1990, only 1.2 million women finished a running race, representing a quarter of all finishers.

Men's running event finishers still grew a robust 19.7 percent to 8.2 million from 6.8 million in 2012. In 1990, there were 3.6 million men finishers.

The total number of U.S. running events reached 28,200, another all-time high, and a 7 percent increase since 2012.

Among formal race events, the 5K maintained the #1 position of all race distances with 8.3 million finishers (another record number), claiming 43 percent of all finishers in the U.S. Correspondingly, the number of 5K events jumped 54 percent to 15.2 million.

The half-marathon again held the #2 position among formal races with approximately 10 percent of the finishers, including an astounding 61 percent female participation. That was followed by 10K, with 7.9 percent of finishers.

10K events held reached 3,200, up 11 percent; and half-marathon events held totaled 2,100, up 8 percent. 8K/5 mile events advanced 7 percent to 2,000.

Approximately 541,000 individuals finished a marathon, representing 2.8 percent overall and up 11 percent year-over-year. The number of marathons reached 1.1 million, up 4 percent. Men represent 57 percent of all marathon finishers.

After the 5K, the fastest growth came in the ‘Others’ events category, which includes mud runs, obstacle runs, color-themed runs and other untimed non-traditional, adventure-type races. Finishers in the ‘Others’ category reached 6.74 million, representing 35.4 percent of all finishers and ahead 22 percent year-over-year. A total of 4,600 ‘Others’ events were held, up 16 percent.

Running USA said U.S. participation in non-traditional events has seen a 40-fold increase since 2009, when participation was in the low six figures. The organization noted that the handful of mass participation adventure series in 2009 has rapidly expanded to more than 35 non-traditional or themed running series that included mud, color, foam, electric, zombie and even ugly sweater runs by 2013.

“Across the country, themed races and obstacle events have attracted a loyal audience of fitness-minded people who want to be active, but not necessarily competitive; many just want to have fun, enjoy the camaraderie of others and focus more on the social, team-building aspect rather than serious competition,” said Running USA. “This proliferation of themed races appeals to nearly everyone and offers a unique twist to the straight-laced classic road races of the First Running Boom by providing participants a less-competitive atmosphere where they can focus on fitness, fun and the experience that they can and do share with friends and family; in addition to possibly contributing to a charitable cause.”

Running USA found that about 60 percent of The Color Run entrants have never run a 5K. Most are brand new runners of all ages with an approximate 50/50 gender split.

Other stats from Running USA’s report:

•    The sweet spot of running event participation continues to fall between the ages of 25 and 44 for both genders (57 percent for women and 48 percent for men), and overall last year, 53 percent of all finishers came from between said age bookends.

•    The average marathon time for women was 4:41:49 while men's was 4:16:37.