But did you think about the wardrobe?
You probably should. The right clothes and gear can make the difference in any sport in performance, comfort -- and the cute Facebook photo you'll want to post at the end of the day, say product developers and seasoned recreational athletes.
Eileen Berner, marketing director for insulator PrimaLoft, is a self-described "weekend warrior" who does obstacle races and climbs mountains and ice in her spare time.
"Clothing is one of the first key decisions you are making in one of these events. You've checked the weather forecast, but the race starts out and you're running up a ski mountain and sweating when it's still cool and by the afternoon, it's really hot," Berner said.
She says she can tackle pretty much anything in her lightweight Patagonia Nano Puff jacket and water-resistant, tight-fitting socks. They are her go-to items.
"The best gear is the gear that when you come back from the event, you weren't cold or hot or have blisters," she said.
For Margaret Schlacter of Salt Lake City, a regular on the Spartan Race circuit, that means nothing cotton. "I made the awful mistake the first time and wore cute cotton yoga capri pants, cotton underwear and a cute cotton T-shirt. After the swimming portion of the race, I had to roll the yoga pants into shorts and keep peeling the shirt away from my body," she said.
"Wearing cotton underwear is like wearing white after Labor Day -- it's a cardinal sin," Schlacter said.
Synthetic fabrics not only help take care of the moisture and regulate temperature better, but they also dry quickly, resist stains and don't retain as much odor, said Greg Thomsen, managing director of Adidas Outdoor.
This new generation of fitness buffs likes outdoor workouts, so makers of athleticwear had already started making the shift to moisture-moving and water-repellant materials, said Susan Branch, global head of products for Roxy.
She also wants sun protection, mesh ventilation and pockets since she might not be ending where she started, Branch said. Those features are becoming standard, she said.
Her recommendations are slim, body-hugging silhouettes for ease of movement that don't snag on obstacles and wider bra straps for support.
Something else athletes might want -- but don't yet know they want -- are flat-locked seams because they reduce chaffing, she said.
Choosing footwear, though, is more specific, Schlacter said. There's a difference between running through a few puddles and submerging your foot.
For a race that does involve more wetness, she skips the water-repellent trail shoes, because, while they keep a certain amount of water out, they'll also keep the water inside the shoe if it gets inside. She predicts that big industry players will soon develop a shoe that's tailor-made for these sort of activities.
Schlacter said she isn't all that concerned what she looks like when she is on the starting line, but there is no reason not to put fashion with function.
She favors simplicity, down to her ponytail reinforced with an elastic headband and sheer lip balm. There's definitely no mascara, she said.
Roxy's Branch, however, makes the case to have it all: "You should have the expectation that products made for this stuff will perform -- and that you can look cute doing it.
"There are trend-right silhouettes that deliver on technical features," she said. "And you know you will put up a photo of you crossing the finish line on social media, so go for it!"
A Tough Mudder race is scheduled for Oct. 5 and 6 in Black Diamond. To register go to toughmudder.com/events/washington-2013/.
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