Kimberly Clements was showing off purple bruises on her biceps and legs, earned in a weekend of bike racing.

“I fell down a hill really hard,” she said, laughing about the crash with her training partners.

It was just a part of cyclocross, a growing form of bicycle racing on short, fast courses covered in grass, sand, mud and obstacles.

“I like the challenge,” said Clements, a 39-year-old marine biologist, while trying to recover from her season-opening race in Texas. “It is a big challenge.”

Popular in Europe for decades, professional cyclocross races look like a mix between a tailgate party and a bike race, with rowdy fans clamoring at the race barriers to see top athletes push their bodies to the limit.

The fall and winter sport is growing more popular in the U.S. In 2013, Louisville, Kentucky, held the sport’s world championship, and race series have spread across the country.

Last fall, the Delta States Grand Prix brought a competitive cyclocross series to Louisiana and Mississippi. Mostly amateur racers, like Clements, tried the spectator-friendly form of bicycle racing, which combines the off-road skill of mountain biking with the speed of road races.

“It’s a really great party with bikes in the middle,” said Wes McWhorter, the director of the Delta States Grand Prix. A longtime cyclist and racer, McWhorter owns Rouler, a company that designs apparel and bike trips. A riding buddy of his mentioned a few years ago he would like to do some cyclocross racing, so McWhorter volunteered with the Louisiana-Mississippi Bicycle Racing Association to make it happen.

The first DSGP race, in New Orleans’ City Park, last year, was the ultimate cyclocross experience.

“It was rainy and muddy,” McWhorter said. “It was perfect. I can’t think of a better way to kick the series off.”

This year’s series opens at Baton Rouge’s Brooks Park on Oct. 26.

Races are short, lasting 30 minutes for beginners — the category 5 racers — and an hour for experts in categories 1 and 2. While racers can use almost any bike, a cyclocross-specific bike looks like a road bike, with curved, drop handlebars and skinnier wheels than a mountain bike. But the frame is a little tougher, and the tires have plenty of grip for bad conditions.

Often laid out in city parks, the courses are about a mile long and are designed to include every inch of sand, water and mud available. Man-made obstacles force riders to dismount and run with their bikes to leap over a series of short walls or climb stairs.

“It’s a mentally and physically exhausting sport,” McWhorter said. “That’s what makes it so intense and so fun.”

While the races are tough, heart-rate raising affairs, they don’t last long compared with most road races.

“I like that it’s only an hour, and you can really push it,” said Matt Gandy, the 23-year-old manager of The Bike Crossing shop in Baton Rouge and last year’s DSGP singlespeed division champion. “You don’t have to train that hard to be decent.”

Even at amateur races, the crowds create a raucous atmosphere.

“You definitely get pumped up by the crowd,” Gandy said.

Spectators are known to offer hand-ups, gifts offered to the racers as they pass.

“It could be a beverage, it could be a piece of bacon, it could be a dollar bill,” McWhorter said. “It really differs. I’ve seen Hot Pockets handed up. I’ve seen all kinds of weird stuff.”

And heckling is a prominent part of the sport. The fans shout, “You’re riding like you’re going for coffee!” Or they confuse the leaders riding well ahead of their competition by yelling, “Dude, he’s right behind you! Go, go, go!”

Gandy likes to shout lines from a Will Ferrell character, stock car racer Ricky Bobby.

“I always pull out the Ricky Bobby,” Gandy said, “If you’re not first, you’re last!”

However, crowds at DSGP races are encouraged to keep it civil.

“We’re all about everybody having a good time but respecting the athletes that are out on the course,” McWhorter said. “It’s about fun, it’s about joking with each other, but it’s not about demeaning another human being.”

Cyclocross is unlike any other form of cycling, said Clements, who had never been very interested in racing until she tried the sport last year.

“It’s a different racing culture,” Clements said. “The culture is what sucked me in.”