Fitness trends come and go—remember Jazzercize?—and right now, the half marathon is ascendant. Last year, two million people finished the 13.1 mile race, and 61 percent of those runners were women. Those are huge numbers, and Scott Douglas and Dan Fuehrer at Runners World have more, charting the race's increasing popularity: 
 
 In 1990, there were an estimated 303,000 finishers. That total had more than doubled by 2004. This year's record total of 1.96 million means that, in just less than a quarter-century, there's been more than a six-fold increase in finishers. 
 
 The race seems especially popular in the United States, where 14 of the 20 most well-attended races were held. But the biggest races of all were overseas: 45,126 people finished a half marathon in Sweden last year, and 40,763 ran one in Great Britain. 
 
 Running USA, the group that compiled the statistics for half marathon runners, points out a few other fun facts about just how many people are running these races: 
 
 Since 2010, 13.1 miles has been the second most popular distance by finishers behind the 5K. Per our count, October hosted the most U.S. half-marathons (288), while January had the least (83) in 2013. Since 2000, the number of half-marathon finishers in this country has quadrupled (482,000 to 1,960,000) or an impressive increase of 307%. 
 
 The difference between a half-marathon and 5K is huge: runners, it seems, are divided between people committed to running for maybe 40 minutes and people ready to hoof it for more than two hours. If you fall somewhere in between, well, maybe it’s about time you try for 13.1 miles. Everyone else is. ||||| In 2013, the half marathon was once again the fastest growing standard distance among U.S. road races, according to data compiled by Running USA, an industry trade group. 
 
 There were an estimated 1.96 million finishers at U.S. halfs last year, up 6% from 2012's total, and a new record. The charts and table below, created using Running USA's data, highlight some key stats and trends about the half marathon's popularity. 
 
 First, the number of finishers in U.S. half marathons has exploded. In 1990, there were an estimated 303,000 finishers. That total had more than doubled by 2004. This year's record total of 1.96 million means that, in just less than a quarter-century, there's been more than a six-fold increase in finishers. 
 
 
 
 Much of the growth has been driven by increased female participation. In 2013, women made up a record 61% of U.S. half marathon finishers, compared to 53% in 2006. Although the percentage of men finishing half marathons has fallen each of the last several years, the absolute number continues to increase. There were more than 760,000 male finishers of U.S. halfs in 2013, which was more than all finishers in 2006. 
 
 
 
 The half marathon isn't just a U.S. phenomenon. Although 14 of the 20 largest half marathons in the world in 2013 were U.S. races, the three biggest were overseas. The 45,126 finishers in Goteborg, Sweden was the most in history for an annual half marathon. 
 
 Race Number of Finishers in 2013 Goteborg (Sweden) 45,126 Great North Run (Great Britain) 40,763 Paris (France) 30,371 500 Festival (Indianapolis) 30,059 Nike Women's San Francisco 26,406 Walt Disney World (Florida) 23,148 Disney's Princess (Florida) 22,739 Berlin (Germany) 22,232 NYRR Brooklyn 21,427 Rock 'n' Roll Las Vegas 20,665 Rock 'n' Roll USA Nation's Capital 19,994 Rock 'n' Roll Philadelphia 18,137 Rock 'n' Roll San Diego 18,077 Country Music (Nashville) 18,022 Madrid (Spain) 15,943 Disneyland (California) 15,871 Miami 14,939 Surf City USA (California) 14,792 Great Birmingham (Great Britain) 14,624 NYC (New York) 14,535 ||||| Jane Seo blazed across the finish line at last weekend's Fort Lauderdale Half Marathon with a stellar time of 1 hour 21 minutes. The professional New York food blogger's blistering 6:15-per-mile pace earned her second place among the thousands who raced. Seo paraded around the finish line while grinning and gripping a gaudy medal. 
 
 But her pace, it turns out, was too good to be true. Seo has now been disqualified for cutting the course — a crime she confessed to only after a computer sleuth crushed her elaborate coverup. A lengthy post published on marathoninvestigation.com documented her lies in exquisite detail. She later posted a four-paragraph apology to her 34,400 Instagram followers. 
 
 “I made a HORRIBLE choice... what an idiot I was!” she wrote in a post that's since been taken down. “I am extremely ashamed… I am so sorry everyone.” 
 
 Suspicions arose almost immediately after Seo, who is 24 and writes regularly for the Huffington Post, crossed the finish line in the 13.1 half-marathon division Sunday. Race timer Josh Stern quickly noted that her timing chip logged unusually fast miles in the second half of the race, when runners often slow down rather than dramatically speed up. He confronted Seo, who persuaded race director Matt Lorraine to keep her listed as the number two finisher, with her time just under 1 hour 22 minutes. 
 
 But after the race, someone tipped off Derek Murphy, a business analyst by day who has become the world's best internet sleuth at busting cheating runners. 
 
 He began digging into Seo's time and soon came across a prime piece of evidence: a photo of her at the finish line that clearly showed her race-tracking Garmin watch. He enlarged the photo, which showed the watch matched her time of 1 hour 22 minutes but also indicated she had covered only 11.65 miles — nearly two miles short of the full race. 
 
 Seo later admitted she'd faked GPS evidence (left) by biking the course; a zoomed-in photo of her watch shows the distance she actually ran. photos via Marathon Investigations 
 
 Murphy also posted the math on what Seo's mile-by-mile splits would have been: 
 
 
 
 10K - 44:22 
 
 13.1 - 1:21:46 
 
 These results would equate to a 7:09 minute/mile pace for the 1st 10k and a 5:25 minute/mile pace for remaining 11.08 kilometers. 
 
 
 
 Very few, if any, runners could shave a minute and a half off their splits in the second half of a race. But there was more evidence. 
 
 Seo, who like many runners posts her activities on Strava.com, later in the day posted mile-by-mile records of her traversing the entire 13.1 miles, most of which run along Fort Lauderdale Beach. But Murphy discerned that the cadence numbers were more in line with a person on a bicycle rather than a runner. 
 
 
 
 Through the Flyby screen, I was able to confirm that she actually covered this course in the afternoon — long after the race was complete. 
 
 Seo later admitted she'd gone back and biked the whole course to cover her tracks by GPS. 
 
 Murphy's site has been blowing up since exposing Seo's lies, and commenters on the web are excoriating Seo, a Harvard grad who regularly writes about food and culture. Her trip to South Florida was partially sponsored by Fort Lauderdale tourism site Sunny.org, Murphy said. 
 
 “Had she just admitted what she did, I never would have heard of her, nor written about her,” Murphy said. “But going back and biking the course to cover up... that’s unheard of.” 
 
 One poster wrote to Seo: “You are an embarrassment to the running community and the runners who slug away to get a sub 2 [break two hours over 13.1 miles]. You're just greedy.” 
 
 And another: “You are not a good person regardless of how fast you may or may not be.” But a third noted that such harshness should be reserved for serious issues. 
 
 Murphy, based in Ohio, began his site two years ago to investigate claims of malpractice by runners aiming for the Holy Grail: attaining a qualifying time fast enough to be eligible for the Boston Marathon. He has even used Google Earth in one case to prove a runner’s “innocence” to claims of course-cutting. 
 
 He said he spoke to Seo Monday, who maintained her innocence, and traded emails with Stern and Lorraine. He broke his story of her cheating Tuesday. 
 
 “While I am glad that she eventually admitted to cutting the course and trying to cover her tracks," Murphy wrote on his site, "she only posted this after information was relayed to her regarding the extent of the evidence against her.” 
 
 He also noted her Instagram post claimed she wasn’t feeling well, “but she had the energy to bike 13.1 miles later that afternoon” and she didn’t look distressed in any of the race photos on the marathon’s site. 
 
 The listings for the half marathon now show Jillian Pollack placing second in a time of 1:23.38. 
 
 Follow Nick Sortal on Twitter @NickSortal.
– Female runners are making half-marathons the sport's most popular distance race, reports Runner's World. It takes note of new stats from Running USA showing that a record 1.95 million people finished a 13.1-mile race last year, which marks a 6% increase from the previous year and an astonishing six-fold rise since 1990. Of last year's finishers, 61% were women, up from 53% in 2004. "Runners, it seems, are divided between people committed to running for maybe 40 minutes and people ready to hoof it for more than two hours," observes Rose Eveleth at Smithsonian. "If you fall somewhere in between, well, maybe it’s about time you try for 13.1 miles. Everyone else is."